Documents published in 2024 : Scipedia

The use of SDMT Data for Local Seismic Response Studies in the Catania Area
A. Cavallaro, S. Grasso, M. Sammito*, A. Scotto di Santolo

ISC2024.

Abstract
Soil stiffness at small strain is a key parameter to solve many geotechnical problems, such as the design of the foundation and the knowledge of the seismic behaviour. There are many methods to perform in-situ soil shear wave velocity measurements: Down Hole test (D-H), Cross Hole test (C-H), Spectral Analysis of Surface Waves (SASW), Multichannel Analysis of Surface Waves (MAWS), etc. Among these methods, the use of Seismic Dilatometer Marchetti Tests (SDMT) to measure the shear wave velocity profile was developed and used in Italy. This test shows good repeatability of the measurements and the possibility to know, at the same time, the mechanical soil characteristics in the static field. In order to evaluate the soil profile of shear wave velocity (Vs), deep site investigations have been undertaken in some Italian sites, prone to high seismic risk. C-H and D-H tests, SDMT and Noise Analysis Surface Waves (NASW) have been carried out. In this paper, the relevance of using the Seismic Dilatometer Marchetti Tests (SDMT) as a basic tool for a comprehensive soil site characterization to carry out a local seismic response study was analyzed.
Abstract
Soil stiffness at small strain is a key parameter to solve many geotechnical problems, such as the design of the foundation and the knowledge of the seismic behaviour. There [...]
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Analysis of DMT Results and Comparison with Other In Situ Tests in a Sensitive Clay of Eastern Canada
V. Silvestri*, C. Tabib

ISC2024.

Abstract
This paper presents a re-evaluation of test results obtained from an extensive series of in-situ tests carried out in a lightly overconsolidated sensitive clay of eastern Canada. The geotechnical investigation involved self-boring pressuremeter tests (SBPMTs), flat dilatometer tests (DMTs), hydraulic fracture tests (HFTs), and vane shear tests (VSTs). The first surprising result is that the in-situ coefficient of lateral pressure at rest, K0, deduced from DMTs, SBPMTs, and HFTs is much higher than expected. Second, the values of the overconsolidation ratio, OCR, computed from DMT data are also much higher than oedometer-deduced values. Third, undrained shear strengths obtained from SBPMT expansion curves are higher than both DMT- and VST- deduced values, with the latter tests yielding very similar results.
Abstract
This paper presents a re-evaluation of test results obtained from an extensive series of in-situ tests carried out in a lightly overconsolidated sensitive clay of eastern [...]
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Comparative Assessment of DMT-Based and CPT-Based Transformation Models for the Estimation of Shear Wave Velocity: a Case Study in Central Italy
M. Uzielli*, D. Marchetti, S. Amoroso

ISC2024.

Abstract
The definition of the shear wave velocity profile is a fundamental step for the seismic characterization of a site in the context of Eurocode 8 and for the conduction of earthquake geotechnical engineering efforts such as site response analysis. Shear wave velocity profiles can be obtained: (1) directly from seismic geophysical and seismic geotechnical tests; or (2) indirectly, from “static” in-situ geotechnical tests such as dilatometer tests (DMT) and cone penetration tests (CPT). In the latter approach, shear wave velocity is estimated by using transformation models which are typically derived from data collected at other sites. This paper illustrates the procedures and main results of the comparative assessment of the performance of existing DMT-based and CPT-based transformation models to estimate shear wave velocity at two adjacent spatial locations in a rural site in the region of Tuscany in central Italy. Model-predicted shear wave velocity profiles were compared with direct measurements obtained by geophysical seismic dilatometer (SDMT) testing. The comparative assessment involved the definition, calculation, and assessment of quantitative performance statistics. The paper provides a critical analysis and a discussion of the outcomes with respect to soil type.
Abstract
The definition of the shear wave velocity profile is a fundamental step for the seismic characterization of a site in the context of Eurocode 8 and for the conduction of earthquake [...]
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DMT-based liquefaction assessment accounting for the fines content effect: a case study Emilia-Romagna italy
R. Cecchi, A. Chiaradonna, P. Monaco*

ISC2024.

Abstract
Simplified methods for seismic liquefaction assessment based on the flat dilatometer test (DMT), in which the liquefaction triggering curve is defined based on the horizontal stress index (KD), have been proposed over the years. One major drawback of the existing methods, valid for clean sand, is the lack of a correction factor for the fines content. An updating of the empirical relationship CRR-KD proposed by Chiaradonna and Monaco (2022) to incorporate the effects of the fines content is currently under development and validation. This paper illustrates the results obtained from application of the new method at the site of San Carlo – Terre del Reno (Ferrara) located in the Emilia-Romagna plain (Italy), where widespread liquefaction occurred in the 2012 seismic sequence. A comprehensive site characterization from previous insitu and laboratory tests carried out by various research groups is available for the sand, silty sand and sandy silt deposits in the San Carlo area. The performance of the new CRR-KD curve accounting for the fines content effect is compared with that obtained by adopting the “clean sand” curves proposed by Chiaradonna and Monaco (2022), as well as with that obtained by using the CPT-based method by Boulanger and Idriss (2014). Even though verified only for specific Italian soils in this area and requiring further field validation, the proposed approach appears as promising to improve the DMTbased liquefaction assessment in silty sands.
Abstract
Simplified methods for seismic liquefaction assessment based on the flat dilatometer test (DMT), in which the liquefaction triggering curve is defined based on the horizontal [...]
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Deformability Parameters in the Offshore In-Situ-Test Survey for the New Breakwater Project in Genova Italy
M. Sacchetto*, D. Marchetti

ISC2024.

Abstract
The harbour of Genova is currently protected by a breakwater barrier that is 4 km long. One of the ongoing PNRR projects in Italy consists in dismissing the current breakwater and rebuilding it farther away from shore. The new breakwater will extend to a length of over 6.2 km and allow large cargo and container ships with over 400 m length to access the harbour. The new breakwater will lie in the currently open and unprotected water of the Genova Bay, with water depths up to 50 m. An extensive in situ test campaign of CPT and DMT tests was carried out for soil characterization, to provide stratigraphy, deformability and strength parameters required for the design of the new breakwater foundations. The Manta seafloor penetrometer designed by Geomil was deployed with a crane, operating from a floating pontoon anchored in turn on each of the test locations. The fully automated version of the flat dilatometer (Medusa DMT) and a CPTU tip were alternatively pushed by the Manta, with penetration depths up to over 27 m from seabed. This paper presents results of the moduli obtained from DMT tests employing the standard Marchetti’ formulas and compares them with the interpretation from the CPT using different correlation factors. Additionally, the correlations between Bq (obtained from CPTU) and Ud (obtained from DMT) are analysed.
Abstract
The harbour of Genova is currently protected by a breakwater barrier that is 4 km long. One of the ongoing PNRR projects in Italy consists in dismissing the current breakwater [...]
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(S)DMT Tests in Structured Soils. Lessons Learned from Portuguese Granitic Massifs Characterization
N. Cruz*, C. Rodrigues

ISC2024.

Abstract
Characterization of structured soils by in-situ tests cannot be interpreted with success by applying the methodologies dedicated to sedimentary soils, due to the presence of cemented structures that deeply influences its mechanical behaviour, deviating from Classical Soil Mechanics concepts. From the shear strength point of view, structured soils are represented by two parameters that must be derived simultaneously (cohesion intercept and angle of shearing resistance), which is only possible to achieve in tests that measure more than one parameter, such as DMT, CPTu or PMT tests. In its turn, deformability of structured soils is characterized by 2 yield points, one related with beginning of weak bonds yield (first yield) and another one related with the complete breakage of the bond structure (bond yield or gross yield), which are not present in de-structured soils. As consequence, moduli decay curves are more pronounced than those typically displayed in sedimentary soils. The research based in Portuguese granitic environs tested by (S)DMT has shown its usefulness in the characterization of these structured materials. The whole research frame included the characterization of several sites by means of CPTu and DMT tests, laboratorial testing, a calibration apparatus where DMTs were performed in artificially cemented soils closely controlled by triaxial and other laboratorial tests and several sets of SDMT, PMT, CPTu and triaxial tests performed in a high-quality experimental site (IPG). The accumulated experience arising from these experimental frames will be summarized and discussed in the present paper.
Abstract
Characterization of structured soils by in-situ tests cannot be interpreted with success by applying the methodologies dedicated to sedimentary soils, due to the presence [...]
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Using Dilatometer to Predict Stress Increase Component of Foundation Settlement
R. Failmezger*

ISC2024.

Abstract
Because soil resists applied stresses in the x, y, and z directions, the ratio of horizontal to vertical stresses, ko, determines the soil stress distribution. The dilatometer test predicts the unit weight of the soil and the horizontal stress ratio at rest, ko, providing the necessary input to determine the stress increase applied to the soil. The Boussinesq stress distribution assumes the soil has a linear elastic stress-strain relationship. This distribution has no input from the soil’s material properties. Harr (1977) proposed using the normal probability distribution with ko input to more accurately compute stress distribution. The authors show the Harr stress distribution for different values of ko and compares them with the Boussinesq stress and Westergaard stress distributions. The authors also present some case studies of stress distribution measurements and proposes modern instrumentation needed for additional research to determine the best prediction method.
Abstract
Because soil resists applied stresses in the x, y, and z directions, the ratio of horizontal to vertical stresses, ko, determines the soil stress distribution. The dilatometer [...]
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Comparative Liquefaction Triggering Assessment of Gravelly Reclamations using the CPT, DPT, and Shear-Wave Velocity
R. Dhakal*, M. Cubrinovski

ISC2024.

Abstract
Major challenges are encountered in characterizing and performing liquefaction assessment of gravelly soils since performing traditional in-situ tests, such as the Cone Penetration Test (CPT), in gravelly soils can be challenging, and since gravelly soils are not well-represented in existing case history databases used to develop semi-empirical methods for liquefaction assessment. This has been the primary reason for the ongoing efforts to develop methods based on other invasive tests, such as shear-wave velocity (Vs), and penetration tests with larger probes and greater energy delivered to the rod, such as the Dynamic Cone Penetration Test (DPT). While CPT-based liquefaction analyses have been comprehensively studied, limited research has been conducted comparatively evaluating the performance of the other two methods. This paper performs liquefaction triggering assessment of gravelly reclamations using data from the welldocumented case history of the port of Wellington (New Zealand) using CPT, DPT, and Vs measurements. Results show that while the Vs measurements overestimate liquefaction resistance, the DPT and CPT agreed relatively well with observations from past earthquakes due to the greater sensitivity of these test methods to soil density and stratigraphy
Abstract
Major challenges are encountered in characterizing and performing liquefaction assessment of gravelly soils since performing traditional in-situ tests, such as the Cone Penetration [...]
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On-site characterization of compacted iron ore tailings-Portland cement blends for dry stacking systems
J. de Sousa Sailva*, H. Mansur Chaves, H. Scheuermann Filho, N. Consoli

ISC2024.

Abstract
Dry stacking of filtered tailings has become feasible due to the development of novel dewatering technologies. It offers an alternative to address the safety-related issues associated with conventional slurry disposal in reservoirs confined by upstream heightened dams. The operation and maintenance of such structures are challenging because of the high degree of uncertainty inherent in this material due to its spatial variability in state and gradation. It is also susceptible to liquefaction when saturated and in a loose state. In contrast, the filtered tailings can be compacted and piled up to hundreds of meters to meet prescribed design requirements. Eventually, a cementing agent can be incorporated into the tailings before compaction to enhance the general engineering properties. Nevertheless, few dry-stack facilities operate; none use cement as a stabilising agent. Accordingly, this paper assesses the mechanical response of artificially cemented iron ore tailings compacted in the field to form an experimental pile. Plate load tests and cone penetration tests were used. The experimental pile was divided into four sections, each compacted with different combinations of roller passes (4 or 6 passes) with and without vibration frequency. The results showed that the compacted material was practically insensitive to variations in compaction parameters, as evidenced by similar results in the tested sections' stress-strain responses and cone tip strength values. This study also highlights the effectiveness of field testing in investigating the response of stacking plants and the importance of using a small amount of cement to achieve adequate mechanical performance.
Abstract
Dry stacking of filtered tailings has become feasible due to the development of novel dewatering technologies. It offers an alternative to address the safety-related issues [...]
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Drying and wetting cycles in tailings dams: effects on physical, mechanical and hydraulic properties
R. Rodriguez-Pacheco, J. Butlanska*, A. Onel Oliva, A. Muñoz-Moreno

ISC2024.

Abstract
The study examines the drying and wetting cycles of tailings dams (TDs) and their impact on physical, mechanical and hydraulic properties. TDs are divided in four zones: the dike, the discharge zone, the transition zone and the distal zone (also known as the decantation pond). The filling process of the tailings dam involves five phases: 1) dumping and wetting, (2) segregation, (3) sedimentation, (4) consolidation, and (5) drying. The occurrence of drying and wetting cycles depends on the water balance, which can be expressed as Inflow = Outflow ± Storage Coefficient. These cycles are influenced by factors such as changes in the discharge point within TD dike and reservoir, weather conditions, and other external factors. The analysis of drying and wetting cycles in TDs reveals several trends: (a) grain size, density, internal friction angle, and permeability decrease from the discharge zone toward the decantation pond and (b) porosity, fine particle content (particle less than 75 microns), plasticity, cohesion, and capillarity height increase as we move toward the decanting lagoon. Despite these findings, there is currently no established methodology for managing the filling process or controlling wetting and drying cycles of TDs.
Abstract
The study examines the drying and wetting cycles of tailings dams (TDs) and their impact on physical, mechanical and hydraulic properties. TDs are divided in four zones: the [...]
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Integrated characterisation of bentonite pellet structures for in situ test installation
J. Torres-Serra*, A. Mesa-Alcantara, E. Romero

ISC2024.

Abstract
Bentonite pellet-based mixtures are currently investigated as candidate materials in large-scale in situ sealing experiments such as the Vertical SEALing project by the Institute for Radiological protection and Nuclear Safety (IRSN, France) due to their expected gap-filling capacity in engineered barrier systems for the geological disposal of radioactive waste. In the short term, after installation, the hydro-mechanical behaviour of these pellet-based structures is governed by pellet-pellet interactions, which have been characterised experimentally by oedometer compression tests and numerically by discreteelement modelling of single-layered pellet skeleton samples. In this work, we integrate these experimental and numerical tools to characterise the compressibility of three-layered pellet-based structures with axis-oriented arrangements. We validate the simulated deformation of bentonite pellet samples against experimental data and analyse the evolution of the dry density distribution and axial stiffness along the oedometer compression curve. Our integrated approach has implications for the emplacement and monitoring in situ tests on multi-layered pellet-based barrier systems.
Abstract
Bentonite pellet-based mixtures are currently investigated as candidate materials in large-scale in situ sealing experiments such as the Vertical SEALing project by the Institute [...]
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Characterization of residual soil in tailings dam foundations: A combined analysis of in-situ tests and geophysical surveys with emphasis on method correspondence
J. Oliveira Barbosa, J. Paulo Souza Silva*, B. Guimaraes Delgado, P. Pazzoto Cacciari

ISC2024.

Abstract
New legislation in Brazil requires that all upstream tailings dams must be closed. However, understanding the characteristics of the foundation and deposits of these dams can be complex, and conventional investigations may not be sufficient. Geophysical methods can complement conventional approaches and provide a better understanding of geotechnical structures. The objective of this investigation is to comprehensively characterize residual soil from a tailings dam foundation by integrating data from direct and indirect approaches. Data from CPTu, SCPTu, SPT, geophysical profiles, and MASW were analyzed. The results were compared with empirical correlations for other soil types, and it was found that the equations are not effective to represent the materials. The study discusses the advantages and limitations of using these empirical equations.
Abstract
New legislation in Brazil requires that all upstream tailings dams must be closed. However, understanding the characteristics of the foundation and deposits of these dams [...]
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Development of a 3D ground model to design the stabilisation of a downstream dam founded on weak and liquefiable units
J. Rola, M. Sottile, N. Rivas, L. Roldan*, A. Sfriso

ISC2024.

Abstract
Athree-dimensional (3D) ground model was developed to design the stabilisation of a dam founded on both weak and liquefiable units up to about 18 m below ground surface. The ground model covers a linear extent of approximately 800 m and was developed from five separate site investigations completed over a four-year period and digitisation/georeferencing of historic drawings/plans. Combined, the investigation comprised 206 cone penetration tests (CPTs), 37 boreholes and 36 test pits, including several vane shear tests, ball penetrometer tests and sampling. CPT data was processed to identify different material behaviours, generally based on the following features: corrected tip resistance; sleeve friction resistance; pore water pressure ratio; state parameter; and the soil behaviour type index. Each CPT interpretation was compared with information from the nearest borehole using a purpose-built python code. This information was reviewed manually in an iterative process to delineate the various geotechnical unit based on CPT response and the physical logs. This process identified a continuous weak organic layer across the site which had not been previously picked-up by the Engineer of Record (EoR). The works identified nine separate geotechnical units, with one of these subdividable based on its CPT response/grain size. The 3D ground model was built in Seequent Leapfrog Geo using the following information: unit levels specified from each CPT, digitised historic drawings/plans and a topographic survey. This paper describes the process of development and presents the full 3D ground model used as critical input to the stabilisation design of the dam
Abstract
Athree-dimensional (3D) ground model was developed to design the stabilisation of a dam founded on both weak and liquefiable units up to about 18 m below ground surface. The [...]
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Evaluation of the susceptibility to flow liquefaction of an iron ore tailings using the state parameter and Yield Stress Ratio approach
A. Faria, M. Junior*, J. Carneiro, M. Dias, G. Pinto

ISC2024.

Abstract
Flow liquefaction is observed in saturated or nearly saturated geomaterials, showing a strain-softening response during undrained shear, primarily in very loose sands and silts, as well as in very sensitive clays. The Cone Penetration Test (CPTu) has been gaining popularity among the geotechnical community to evaluate the state of a soil profile due to its good repeatability, detailed information on the soil stratigraphy and extensive detailed scientific studies to guide the application of the test results. Susceptibility to flow liquefaction is typically evaluated by estimating the in-situ state parameter (ð) since it directly correlates to the soil behaviour at large strain, as shown by Jefferies & Been (2016). Mayne & Sharp (2019) suggested using the yield-stress-ratio (YSR = σp’/σv0’) to estimate the soil state using a threshold of YSR ≈ 3. Currently, in the Brazilian Mining Industry, it is common to find the application of different approaches to evaluating the susceptibility of mining tailings to flow liquefaction (e.g., Plewes et al., 1992; Olson, 2001; Shuttle & Cunning, 2008; Robertson, 2016). This paper presents an evaluation of the susceptibility of an iron ore tailings (IOTs) to flow liquefaction using the following recently published approaches: i) Mayne and Sharp (2019), using the yield stress ratio (YSR) approach; ii) Smith et al. (2021), using a generalised CPTu state parameter inversion method based on the NorSand Widget; and iii) Robertson (2022), with the updated Kc. The main results show a good convergence between the three methodologies used.
Abstract
Flow liquefaction is observed in saturated or nearly saturated geomaterials, showing a strain-softening response during undrained shear, primarily in very loose sands and [...]
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Difficulties in Building a Ground Model When Lacking Historic Data Archives and its Impact in TSF Safety Assessment
I. Lopes*, M. Garcia, G. Tavares

ISC2024.

Abstract
Sometimes, when working in TSF safety analysis, the historic archives with the original ground topography or details about the TSF design and construction are few or inexistent. The knowledge of the bedrock position, as the details about the embankment construction are essential to know, for instance, the tailings thickness and the construction type. For the analysis of TSF current state stability the ground/structure model is essential, and is, in many cases, very difficult to define with few and low-quality data. The original ground topography is, often, obtained from aerophotogrammetric reconstruction, from satellite images or aerial photos, originally with low resolution and uncertainty of more than 10 m for the elevation. In this paper is presented a case-study from a TSF where the initial data package had only the feasibility design and some very simplified reports that checked the stability of the dam before an upstream raising, i.e. it didn’t exist much information and the details about the site and about the structure were very limited. To “add” difficulties to the process of defining the bedrock surface and to establish the TSF design, the embankments were built with local rocks (mainly schist and phyllite), and during the initial analysis of historical satellite images it was noticed that the original ground was excavated in different areas to increase storage area and obtain construction materials. This paper presents the steps developed to establish the definition of the bedrock ground surface and the difficulties felt and its impacts on TSF safety assessment are discussed.
Abstract
Sometimes, when working in TSF safety analysis, the historic archives with the original ground topography or details about the TSF design and construction are few or inexistent. [...]
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CPTu for Assessment of Flow Liquefaction of Tailings with Similar Physical Characteristics
C. Lebron*, M. Pio dos Santos Junior, A. Viana Da Fonseca

ISC2024.

Abstract
A geotechnical assessment of mine tailings state conditions using the static cone penetration test performed at different tailings storage facilities (TSF’s) will be presented in this paper. Both tailings evaluated herein are deposited as a slurry (hydraulic deposition) and have similar grain-size distribution curves. A set of Cone Penetration Tests (CPTu) with pore pressure measurements were performed at each site to evaluate the state of the tailings. To assess the contractive-dilative behavior classical methodologies were adopted such as i) the contractive/dilative boundary suggested by Robertson (2016) ii) the approach suggested by Plewes et al. (1992) and cited by Jefferies and Been (2016) and iii) the yield stress ratio method proposed by Mayne and Sharp (2019). Partial drainage effects will be identified with classical methodologies. The results were compared to evaluate the difference and limitations of each methodology. Comments on the similarity between the two tailings evaluated herein will also be presented to explain the differences in behavior due to aspects such as mineralogy, gradation, stress history and deposition.
Abstract
A geotechnical assessment of mine tailings state conditions using the static cone penetration test performed at different tailings storage facilities (TSF’s) will be presented [...]
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Geotechnical Parameters of Filtered Tailings and Waste Rock from the Itabira Complex used in Stacking Projects
D. Eloi*, M. Paganin, D. Bastos, W. Maciel, M. Filho, R. Silva

ISC2024.

Abstract
The complex where we used the materials ins this study, explores iron ore in an open pit process and is formed by a significant number of mines, and all their geotechnical structures such as waste rock stackings, tailings dams and, recently, the stackings that are being constructed with waste rock and tailings. For the piles formed by the shared disposal of waste rocks and filtered tailings, the characterization of the materials and the strength and critical state parameters determined the executive methodology and the safety factors required for the projects. The waste rocks and filtered tailings are mechanically disposed and divided into zones defined not only according to the geotechnical characteristics of the materials, but also the structural and operational needs of the stacking, which are divided into the confining zone and the confined zone. In the confining zone, compacted waste is deposited. The aim of this procedure is to enhance the structural performance by employing materials with higher resistance. In the confining zone, as closer to the outer layer of the pile, greater shear strength is mobilized. In the confined zone, friable waste, and mining tailings are disposed. In this zone, there is less mobilization of shear strength. For tailings, control and evaluation adhere to parameters outlined by the Critical State Line, employing the void ratio control of layers. This ensures dilatant mechanical behaviours for all confinement stresses specified in the project.
Abstract
The complex where we used the materials ins this study, explores iron ore in an open pit process and is formed by a significant number of mines, and all their geotechnical [...]
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Effects of Vane Size and Aspect Ratio on the Measurement of Undrained Shear Strength of a Fine-Grained Soil
T. Chatfield*, R. Rinehart, C. Fontaine

ISC2024.

Abstract
The field Vane Shear Test (VST) is a widely used in-situ test method to measure undrained shear strength and sensitivity of saturated, fine-grained soils. The United States Bureau of Reclamation (Reclamation) commonly performs this test method to help inform numerical modeling of earth embankment dams when undergoing a risk analysis or design. Although the test method itself has been a geotechnical tool for quite some time, its primary use has traditionally been limited to sites with soft and/or relatively shallow clay soil. Typically, embankment and foundation materials of interest at Reclamation facilities are at greater depths, under higher effective stresses, and can be relatively stiff. Testing of stronger soils poses issues when performing the VST; typical commercially available equipment has a limited torque capacity to cause yielding of the soil. As a solution, modifying the dimensions and aspect ratio of the vane is an economic means of increasing the measurable range of undrained strength. Yet, the effects of these modifications are not well understood. Soil strength anisotropy is one of the primary components of this uncertainty. Testing on a sandy lean clay has been conducted to enable side by side comparisons of traditional aspect ratio vanes versus the proposed modified vanes to quantify the potential differences in measured undrained strength. In addition, measured undrained strengths from the various vanes are compared to results of laboratory testing on the same sandy lean clay (i.e., direct simple shear and triaxial compression) to provide a better understanding of the differences between the in-situ and laboratory test methods. This paper presents the apparatus developed to allow full scale vane shear tests to be conducted in the laboratory and summarizes the results of tests on a normally consolidated sandy lean clay.
Abstract
The field Vane Shear Test (VST) is a widely used in-situ test method to measure undrained shear strength and sensitivity of saturated, fine-grained soils. The United States [...]
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Analysis of Shear and Consolidation Behaviour of a Clay Foundation Below a Tailings Storage Facility
T. Armstrong*, T. Grobler

ISC2024.

Abstract
Historically, the analyses of tailings storage facilities (TSFs) have primarily focused on understanding the characteristics of tailings, while often overlooking a comprehensive evaluation of the foundation, as seen at Mount Polley in 2014. The Global Industry Standard on Tailings Management (GISTM) Requirement 5.4 stresses the importance of comprehensively addressing all potential failure modes. Numerous platinum TSFs in Southern Africa are underlain by residual clay, specifically a residual mafic rock from the Bushveld Complex. Similar soils, known as "tropical black clay soils", are found in other regions of the world. Surprisingly, there's limited public information on testing and modelling the behaviour of this clay foundation. This paper presents a case study that employs a novel approach to assess the impact of loading from tailings deposition on the underlying clay foundation of an upstream TSF. The analysis investigates how shear behaviour and consolidation characteristics of the clay foundation change with varying TSF heights and construction rates. The approach includes quantifying excess pore water pressures and their influence on the clay foundation's effective stress. The analyses primarily employ traditional limit equilibrium methods to assess TSF stability and foundation behaviour, with the potential to expand to numerical modelling. The study concludes that excess pore water pressures will significantly affect the Factor of Safety (FoS) of a TSF, particularly with adverse consolidation characteristics and increasing TSF height. This is primarily due to the low permeability and changing consolidation coefficient (cv) of the clay layer as the surcharge load increases. Furthermore, the research reveals that, depending on the rate of rise, tailings deposition may induce excess pore water pressures, potentially reducing the FoS. The ability to quantify excess pore water pressures using this novel approach enables a more accurate estimation of the FoS for facilities underlain by low-permeability materials, either residual or transported.
Abstract
Historically, the analyses of tailings storage facilities (TSFs) have primarily focused on understanding the characteristics of tailings, while often overlooking a comprehensive [...]
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Temperature based Leakage Detection and Monitoring Systems in view of Tailings Storage Facilities
G. Dumont, A. Fabritius*

ISC2024.

Abstract
Characterizing the in-situ state of soils is essential for evaluating their vulnerability and the consequences of failure. The cone penetration test (CPT) enables efficient, repeatable, and continuous soil characterization based on the recorded response to penetration. Particularly for waste storage facilities, analysis of CPT results can help avoid failures that could lead to significant socio-economic and environmental impacts. Human-made soils in waste storage facilities, like coal combustion products and mine tailings, can have a large fraction of silt-sized particles, which makes them prone to experiencing partial drainage during CPT soundings at standard penetration rates. However, the current state of practice still predominantly adopts the assumption of fully drained or undrained conditions, which may lead to inaccurate interpretation of soil properties and state. This study aims to explore a new CPT-based characterization framework for intermediate silty soils using cone tip resistance values to determine the soil state. To do so, CPT soundings were performed in-flight in centrifuge models of a coal combustion product with different initial densities at varying penetration velocities. Soils with a low density and contractive behavior experience a decrease in tip resistance as the penetration velocity is increased due to the generation of excess pore pressures, resulting in high ratios of drained to undrained tip resistance (Qtn,drained/Qtn,undrained). In contrast, the tip resistance increases with penetration velocity, resulting in low Qtn,drained/Qtn,undrained ratios in soils of a high density and dilative behavior. The proposed framework uses Qtn,drained/Qtn,undrained to identify contractive layers and is expected to help assess the vulnerability of soil layers to experience liquefaction failure.
Abstract
Characterizing the in-situ state of soils is essential for evaluating their vulnerability and the consequences of failure. The cone penetration test (CPT) enables efficient, [...]
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Characterization of coal combustion products using variable rate CPT in a geotechnical centrifuge
J. Chen, A. Martinez*

ISC2024.

Abstract
Characterizing the in-situ state of soils is essential for evaluating their vulnerability and the consequences of failure. The cone penetration test (CPT) enables efficient, repeatable, and continuous soil characterization based on the recorded response to penetration. Particularly for waste storage facilities, analysis of CPT results can help avoid failures that could lead to significant socio-economic and environmental impacts. Human-made soils in waste storage facilities, like coal combustion products and mine tailings, can have a large fraction of silt-sized particles, which makes them prone to experiencing partial drainage during CPT soundings at standard penetration rates. However, the current state of practice still predominantly adopts the assumption of fully drained or undrained conditions, which may lead to inaccurate interpretation of soil properties and state. This study aims to explore a new CPT-based characterization framework for intermediate silty soils using cone tip resistance values to determine the soil state. To do so, CPT soundings were performed in-flight in centrifuge models of a coal combustion product with different initial densities at varying penetration velocities. Soils with a low density and contractive behavior experience a decrease in tip resistance as the penetration velocity is increased due to the generation of excess pore pressures, resulting in high ratios of drained to undrained tip resistance (Qtn,drained/Qtn,undrained). In contrast, the tip resistance increases with penetration velocity, resulting in low Qtn,drained/Qtn,undrained ratios in soils of a high density and dilative behavior. The proposed framework uses Qtn,drained/Qtn,undrained to identify contractive layers and is expected to help assess the vulnerability of soil layers to experience liquefaction failure.
Abstract
Characterizing the in-situ state of soils is essential for evaluating their vulnerability and the consequences of failure. The cone penetration test (CPT) enables efficient, [...]
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Cone penetration test assessment to identify fluid-like tailings to support a tailings storage facility deconstruction
G. Quaglia*, I. Cueto

ISC2024.

Abstract
This paper presents the implementation of a Cone Penetration Test (CPT)-based methodology to identify fluid-like tailings in the Tailings Storage Facility (TSF) pond to support a TSF deconstruction. The TSF discussed in this paper was partially raised upstream and classified as very high risk due to its location, next to a creek and a short distance to the downstream community. The owner's preferred mitigation strategy was to proceed with the TSF deconstruction. To inform the deconstruction planning, a comprehensive geotechnical site investigation was conducted, which included CPTu and boreholes with continuous thin wall tube sampling from a floating platform. The investigation identified tailings in the pond as high plasticity clays (CH) with a geotechnical fines content exceeding 95 %. The CPT results indicated low tip resistance, nearly linear pore pressure measurements, and minimal sleeve friction, suggesting the presence of fluid-like tailings in a significant portion of the TSF. The implementation of this methodology allowed to systematically confirm the presence of fluid-like tailings across the pond and define their extent. This information supported the owner’s decision to employ mechanical excavation taking advantage of the tailings flowability. The observations made during the tailings excavation confirmed a good agreement between the CPT assessment and the actual material behaviour. These findings underscore the efficacy of the CPT-based method in guiding safe TSF deconstruction projects
Abstract
This paper presents the implementation of a Cone Penetration Test (CPT)-based methodology to identify fluid-like tailings in the Tailings Storage Facility (TSF) pond to support [...]
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Evaluating the dynamic liquefaction potential of tailings: a comparison of simplified methods
L. Roldan, F. Spinazzola*, M. Sottile

ISC2024.

Abstract
The state of the practice to evaluate the dynamic liquefaction potential of a soil column entails the use of simplified methods that compares the cyclic stress ratio with the cyclic resistance ratio. One of the most used methods is the Boulanger & Idriss 2014, which relies on cone penetration test data to estimate in-situ cyclic resistance ratio and cyclic stress ratio distributions, considering corrections factors for soils with fine contents. Saye, Olson and Franke in 2021 presented a novel method to assess liquefaction susceptibility using cone penetration test data on soils ranging from non-sensitive clays to clean sands. The procedure was developed using +400 documented case records of liquefaction and non-liquefaction in clean sands, silty sands, sandy silts, and low plasticity fine grained soils. Although promising, this method is not widely used in the industry yet. This paper presents a comparison between both methods for tailings. It uses cone penetration test soundings performed in tailings with a wide range of mineralogy and fine contents, combined with variations in peak ground accelerations and magnitudes. This analysis shows that Saye, Olson and Franke’s method is generally more robust, particularly for the analysis of fine tailings, as Boulanger & Idriss’ method relies on site specific data or the engineer’s judgement to define an Ic cut-off value that screens out clay-like soils from the liquefaction analysis.
Abstract
The state of the practice to evaluate the dynamic liquefaction potential of a soil column entails the use of simplified methods that compares the cyclic stress ratio with [...]
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Correlation Between Shear Wave Velocity From Borehole Seismic and CPT Data for the Application of Numerical Analysis
U. Matthiesen*, M. Pohl

ISC2024.

Abstract
The Federal Waterways and Shipping Administration of Germany is currently planning the construction of a lock next to the existing Lueneburg twin ship lift on the Elbe Lateral Canal. The vertical lift of both the ship lift and the new lock is 38 m. The lock will be the biggest of its kind worldwide and will require an excavation pit of about 260 m length, 60 m width and 26 m depth. The adjacent ship lift is a major constraining factor for the project, as it must remain in operation throughout construction and thereafter. As part of an extensive site investigation, geophysical crosshole measurements were carried out up to a depth of 70 m to obtain dynamic soil properties necessary for the numerical analyses. This paper shows the results of the geophysical survey as well as a comparison of the in-situ measurements with well-established CPT correlations. The comparison shows a moderate to good match for the dynamic soil parameters such as the smallstrain shear modulus Gmax or the shear wave velocity Vs respectively, providing confidence in the derived soil parameters across the site.
Abstract
The Federal Waterways and Shipping Administration of Germany is currently planning the construction of a lock next to the existing Lueneburg twin ship lift on the Elbe Lateral [...]
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Probabilistic soil model for seismic risk assessment based on SDMT results
Y. Vargas-Alzate*, D. Tarragó, A. Zapata-Franco, A. Gens

ISC2024.

Abstract
A new geotechnical site investigation has been conducted in the southern breakwater basin of the Port of Barcelona, for which hundreds of in-situ and lab tests have been performed. Among these tests, this study focuses on the evaluation of triple points. That is, at the prospected locations, there are results from seismic dilatometer Marchetti test (SDMT), cone penetration tests (CPTu), and laboratory tests based on soil samples. Based on this information, the probabilistic distribution of the dynamic and geometrical properties of the soil profiles can be properly characterized. Eleven closely spaced boreholes have been used to characterise the statistical properties of the input variables. The objective of this article is twofold. First, the probabilistic generation of one-thousand soil profiles, which are statistically compatible with the data provided by the eleven aforementioned boreholes. Secondly, to analyse how the elastic properties of the generated soil profiles evolve once seismic waves have passed through them. To do so, a large set of ground motion recorded in hard soils have been employed. Results show that the dynamic response of the soil can be properly parametrized if considering intensity measures extracted from the ground motions acting at the bedrock level. From the results obtained, fragility functions have been derived for risk assessment purposes.
Abstract
A new geotechnical site investigation has been conducted in the southern breakwater basin of the Port of Barcelona, for which hundreds of in-situ and lab tests have been performed. [...]
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Estimation of the Soil Unit Weight of Mining Tailings through the Application of Machine Learning Techniques
H. Nierwinski, T. Menegaz*, E. Odebrecht, F. Schnaid, R. Pfitscher, F. Mantaras

ISC2024.

Abstract
There are several correlations in the literature that allow an estimate of the soil unit weight for natural soils, but when dealing with materials whose actual specific gravity of solids is outside the range of natural soils for which the correlations were developed, doubts arise, as occurs in the interpretation of tests on mining tailings. Therefore, the present paper aims to evaluate the application of a previously developed approach supported by machine learning techniques for estimating soil specific weights for mining tailings. This approach was developed considering a more comprehensive range of the specific gravity of solids. So, this work relies on a database with results of CPTu tests carried out in different mining tailings deposits from Brazil to estimate specific weights. The values of the specific weights obtained from the machine learning model were compared with literature data, presenting a suitable fit. The research demonstrates that artificial intelligence can contribute positively to the estimation of reliable design parameters and add security to the development of designs of mining tailings containment structures.
Abstract
There are several correlations in the literature that allow an estimate of the soil unit weight for natural soils, but when dealing with materials whose actual specific gravity [...]
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Enhanced, statistically-controlled integrated model of geo-data based on CPTu
J. Wierzbicki, K. Stefaniak

ISC2024.

Abstract
The paper presents the possibilities of geostatistical analysis of geotechnical data using cluster analysis. As a result of the analysis, geological data from boreholes were replaced by digital data corresponding to parameters measured during CPTU static sounding. A unified database with a depth resolution of 2 cm was obtained, allowing it to be used to build geostatistical geotechnical models, e.g. using kriging. Techniques providing statistical control of the homogeneity of geotechnical separations, based only on measured data and not on interpolated or correlated data, were used to create the model. The technique used makes it possible to create an integrated geo-engineering model of the subsoil even for small sites with limited data.
Abstract
The paper presents the possibilities of geostatistical analysis of geotechnical data using cluster analysis. As a result of the analysis, geological data from boreholes were [...]
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Susceptibility mapping for shallow landslides in Tierras Altas, Chiriqui, Panama : An integration of geophysical measurements
C. Caballero*, P. Castillo, J. Castrellon, S. Rodriguez, J. Gallardo

ISC2024.

Abstract
The Tierras Altas region in Chiriqui, Panama presents a high agricultural activity susceptible to extreme climatic events, especially precipitation and surface runoff due to its high moisture retention capacity soils. A mountainous region with heavy winter rainfall and dry summers, part of the Chiriqui volcanic arc, and the point of triple convergence of the Coco, Nazca, and Panama microplate, also makes it a seismic threat zone. Historically, the Tierras Altas district has been susceptible to landslides, floods, and erosion-related phenomena. Through site characterization and the survey of ground dynamics, the research aims to build the input data of geological parameters and analyze dynamic properties through geophysical measurements of surface accelerations, allowing the characterization of the region and the coupling of the soil with climatic and seismic triggers. The results focus on geospatial maps and georeferenced datasets. The preliminary results were obtained through a GIS-based methodology that mapped the physical and dynamic properties of soils, identified high susceptibility zones, and analyzed how the measured dynamic data adjusted the Vs30 model.
Abstract
The Tierras Altas region in Chiriqui, Panama presents a high agricultural activity susceptible to extreme climatic events, especially precipitation and surface runoff due [...]
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The Pseudo-N Values: Proposal and Practice
K. Suto*

ISC2024.

Abstract
The N-value by the standard penetration test (SPT) is commonly used for site characterisation in geotechnical engineering. S-wave velocity, typically estimated by borehole measurement or seismic survey, is also indicative of the strength of the ground. Many researchers attempted to find precise relationships between these parameters. However, N-values estimated from S-wave velocity using these formulae are subject to substantial errors, and the errors are inevitable due to the different nature of the parameters. The formula for pseudo-N value was first proposed in 2011 as (Suto, 2011). This is a simplified formula derived from the formulae found by the previous authors. By using this simple formula as a common practice, with understanding of existence of error, the results can be compared from site to site. This presentation first compares the N-value and S-wave velocity in their natures, methods, practice and cost. Then it examines the previously published formulae and proposed formula of pseudo-N value. Some examples of use of the pseudo-N values are also presented at the end.
Abstract
The N-value by the standard penetration test (SPT) is commonly used for site characterisation in geotechnical engineering. S-wave velocity, typically estimated by borehole [...]
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Critical Shear-Wave Velocity Case Histories for Liquefaction Triggering Curves in Gravel
K. Rollins, N. Salvatore*, B. Cox, T. Jackson

ISC2024.

Abstract
In 2022, a new set of probabilistic shear wave velocity (ðð) based liquefaction triggering curves was developed for gravelly soil by Rollins et al., using a dataset of 96 liquefaction and 78 no liquefaction case histories from 17 earthquakes in seven countries. Although these curves provide liquefaction assessment based on direct field performance, they suffer from the fact that there are relatively few case histories for high ð¶ðð and high ðð values to define the shape of the upper branch of the triggering curves. Thus, we made shear wave velocity measurements at three sites in Valdez, Alaska where liquefaction did not occur in the Mw 9.2 1964 Great Alaska earthquake. The Multi-channel Analysis of Surface Wave (MASW) technique was used to develop several median Vs profiles at each site that account for uncertainty in the experimental dispersion data and inversion parameterizations. ðð-based liquefaction evaluations were then made at each site, using the ðð profiles derived from each solution. Results from previous Dynamic Cone Penetrometer (DPT) tests were then used in selecting the most reasonable velocity interpretation. Based on this VS profile, the layer most likely to liquefy was selected and used to define ðð1 and ð¶ðð7.5 at the middle of this critical layer, obtaining three points of no liquefaction, that could change the shape of the upper branch of the existing VS-based liquefaction triggering curves. These preliminary results suggest that it might be necessary to shift the triggering curves to the left or steepen their slope to provide better agreement with observed performance.
Abstract
In 2022, a new set of probabilistic shear wave velocity (ðð) based liquefaction triggering curves was developed for gravelly soil by Rollins et al., using a [...]
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Cone Penetration Test Data Interpretation for Layered Tailings Storage Impoundments with Perched Phreatic Surfaces
A. Schteinman, H. William*, S. Nazem

ISC2024.

Abstract
Cone penetration testing (CPT) is a widely used technique for soil characterisation. The introduction of the Global Industry Standard for Tailings Management (GISTM) in 2019 increased the necessity for understanding tailings properties (particularly shear strength), requiring better risk management and monitoring of tailings storage facilities (TSFs) to achieve zero fatalities. The complexity of tailings materials, influenced by ore processing, slurry deposition and water management techniques, causes greatly different geotechnical characteristics compared to other soils, requiring specialised monitoring equipment and in-depth investigation. One main aspect in interpretation of tailings properties is understanding the pore water pressure (PWP) within the deposited tailings layers which has often been overlooked in engineering studies. For example, in cases of interbedded layers of silt and sand, the downward drainage due to underdrain systems and lateral flow due to differences in lateral and vertical hydraulic conductivities can lead to the formation of distinct ‘perched’ phreatic surfaces in-between layers due to dissimilarity in material permeabilities. The use of commonly assumed linear PWP profiles in such cases can result in misinterpretations, hence, overestimation of tailings’ effective strengths. In these instances, instruments like vibrating wire piezometers (VWPs) have been widely used. However, VWPs provide limited data for understanding the true PWP profile. CPT with PWP measurements (CPTu) has therefore become a practicable technique for identifying internal PWP and distinguishing deposited layers. As such, a detailed approach to CPT data interpretation is required for interlayered tailings facilities with perched phreatic surfaces. This paper presents how CPTu techniques, combined with graphical interpretation, and VWP data can be used to understand complex internal profiles of interlayered TSFs.
Abstract
Cone penetration testing (CPT) is a widely used technique for soil characterisation. The introduction of the Global Industry Standard for Tailings Management (GISTM) in 2019 [...]
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Vulnerability of levees impacted by seepage near the Kettős-Kőrös River in Hungary
E. Koch*, M. Mayassah, R. Ray

ISC2024.

Abstract
Due to climate change over the last decades, flood events in Hungary and other European countries have become increasingly frequent, with greater intensity and duration. These changes have impacted flood protection levees. A longduration flood allows water to seep into the levees, saturating them and maximizing the potential for damage. Seepage through earthen levees is often observed during floods and can lead to levee failure if combined with internal erosion. This study assesses the levee vulnerability relative to seepage by considering the characteristic time scales of the seepage phenomena and the main factors driving them. The procedure is applied to the Körös sub-basin (Hungary), a site that has shown a continuous trend of increased water levels in recent years. Along the critical section of the levee, a comprehensive site investigation was carried out. The analysis has shown that hydraulic conductivity is the most significant parameter when considering seepage for levees along the Kettős-Körös River. The investigated dyke geometry shows higher vulnerability to lower water levels associated with a longer duration of flood water levels.
Abstract
Due to climate change over the last decades, flood events in Hungary and other European countries have become increasingly frequent, with greater intensity and duration. These [...]
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Basic study for propagation characteristics of elastic wave around subsurface cavities
Y. Hara*, R. Kuwano

ISC2024.

Abstract
This study examines the detection of subsurface cavities using seismic wave propagation. Both vertical and horizontal excitation methods were employed to measure the reflection characteristics of artificially constructed cavities in a test field. The study was conducted at the Le Petau golf course in the town of Abira, Hokkaido, Japan. In this study, a new horizontal excitation technique was introduced along with conventional vertical excitation to compare its effectiveness in identifying wave reflections caused by cavities. An artificial cavity was created using rubber balloons reinforced with cardboard to simulate subsurface anomalies. The measurement used 24 geophones connected to an automatic data logger, and the acquired data underwent extensive analysis with bandpass filtering, amplitude normalization, and deconvolution to elucidate the interaction between the elastic waves and the subsurface structures. The results showed that horizontal excitation provided a clearer view of the cavity due to reflected waves. This is because only SH waves are excited and observed in the horizontal excitation mode. However, this study also recognized that it is difficult to distinguish the boundary between direct and reflected waves at shallow cavity depths, suggesting the need for excitation methods capable of generating shorter wavelengths to improve resolution. This study highlights the potential of integrating vertical and horizontal excitation methods in seismic surveys to enhance subsurface cavity exploration, and highlights future research issues, such as improving waveform analysis techniques and searching for alternative excitation sources, to advance the field of subsurface exploration.
Abstract
This study examines the detection of subsurface cavities using seismic wave propagation. Both vertical and horizontal excitation methods were employed to measure the reflection [...]
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Effect of Hammer Energy and Corrections on the Correlation between SPT N-Value and Shear Wave Velocity
M. Yadhunandan, P. Anbazhagan

ISC2024.

Abstract
The pressuremeter measures both the pressuremeter modulus and the limit pressure, which are used to estimate the bearing capacity of the foundation according to different standards. The results of the pressuremeter test include the pLM limit pressure and the EM pressuremeter modulus. These quantities cannot be directly input as data for geotechnical calculations using Finite Elements or Finite Differences in the study of civil engineering structures such as retaining walls, tunnels, embankments, and excavations. These modern calculation methods require, at a minimum, knowledge of the mechanical characteristics of the soil, including elasticity (with Young’s modulus (E) and the Poisson ratio ()) and resistance (with cohesion (c’) and the angle of friction (’)). This study is devoted to the interpretation of the pressuremeter test so that it is possible to use it for the determination of the mechanical characteristics of the soil. When the pressuremeter test is carried out into clay, it appears pore pressure during the test when only shearing is applied. In summary, understanding pore pressure and interpreting measurements to determine the effective shear modulus are crucial for geotechnical engineering and subsurface exploration. Effective shear modulus can differ significantly from the value determined solely based on total pressure. This study provides the theoretical value of the Skempton coefficient B. Additionally, it proposes an interpretation theory for the pressuremeter test in clay. Finally, the theory is validated through a comparison with tests performed in London clay at a depth of 20.6 meters
Abstract
The pressuremeter measures both the pressuremeter modulus and the limit pressure, which are used to estimate the bearing capacity of the foundation according to different [...]
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Peak Deviator Stress and Strain Uncertainty of Isotropically Consolidated Triaxial Compression Tests on Saturated Non-Cohesive Soils
A. Miliopoulou*

ISC2024.

Abstract
This paper presents the methodology for calculating the peak deviator stress and strain at peak deviator stress uncertainty of triaxial compression tests on water saturated, non-cohesive soils consolidated under isotropic conditions. A silicious sand sample is prepared in the same way to produce identical cylindrical specimens. These are then tested under the same conditions. Type A and type B uncertainty are calculated separately and used to yield the combined and expanded uncertainty of the main results, peak deviator stress and strain at peak deviator stress. For both measurands, type A uncertainty is significantly higher that type B and it is the factor mainly affecting the overall uncertainty of the results
Abstract
This paper presents the methodology for calculating the peak deviator stress and strain at peak deviator stress uncertainty of triaxial compression tests on water saturated, [...]
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The Role and Performance of Instrumentation and Monitoring in Managing Risk During Deep Shaft Excavation in the Mercia Mudstone
J. Birks*, I. Papadatos, M. Rufo

ISC2024.

Abstract
The HS2 Bromford Tunnel intermediate shaft has an external diameter of 21.9m and a depth to formation of 47.1m below ground surface. The shaft is formed with a 63.1m deep 1.5m thick diaphragm wall primary lining, with a cast in situ secondary lining. The shaft works started in spring 2022, and formation level was reached in late 2023. Situated at the base of the Tame valley, the shaft excavation is predominately in the Mercia Mudstone, and is understood to be the largest and deepest excavation of its type in the Birmingham area. Instrumentation and monitoring played a vital role in managing ground risks during the diaphragm wall installation and bulk excavation. The paper covers: An overview of the shaft works and the subsequent tunnelling in the area; The geotechnical risks and parameters to be monitored; The specification, installation and performance aspects of the instrumentation, including the embedded SAAs and Vibrating Wire Piezometers; The design and performance of the specialists’ subcontractors dewatering system and excavation groundwater pressure behaviour during construction; Ground movements and third-party asset monitoring during diaphragm wall installation and excavation; diaphragm wall deflections during excavation - a comparison between design model calculations and actual monitored movement. As the shaft was constructed largely in advance of the main tunnelling works, some of the potential benefits from the experience and field observations made during the shaft works have been realised during the tunnelling.
Abstract
The HS2 Bromford Tunnel intermediate shaft has an external diameter of 21.9m and a depth to formation of 47.1m below ground surface. The shaft is formed with a 63.1m deep [...]
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Dark Fibre Optic Cables for Shallow Ground Charactrization alongside Railroads
E. Obando Hernandez, A. van Uitert*, P. Hölscher, P. Doornenbal, C. Mas, J. van ‘t Schip

ISC2024.

Abstract
We evaluated the feasibility of existing fibre optic telecommunication cable as a Distributed Acoustic Sensors (DAS) for shallow ground characterization alongside railways and using the running trains as seismic source. We utilized 5 km of fibre optic cable alongside a railway segment localized in the Hanzelijn corridor in the Netherlands. For almost a week, we recorded strain generated by passing trains that was utilized to retrieve coherent and multimodal Rayleigh waves at various soil conditions. The data was recorded in a continuous mode, using a channel spacing of 1.0 m and a sampling frequency of 1,250 Hz. The DAS interrogator was set to a gauge length of 2.0 m to reach the highest possible spatial resolution. We captured at least 60 train passages (running alongside the fibre optic cable) per day. We extracted Rayleigh waves by utilizing seismic interferometry method. The seismic interferometry processing provided virtual broad-band shot-gathers with coherent and clear surface waves trends. The computed phase velocity spectrum at frequencies as high as 30 Hz and wavelength as short as 6 m. The retrieved dispersion curves allowed us to determine S-wave velocity profile at a minimum depth of exploration of 2.0 m. The measured Rayleigh waves and calculated S-wave velocities are comparable to reference values measured with standard Geophone and geotechnical data available at the test segment.
Abstract
We evaluated the feasibility of existing fibre optic telecommunication cable as a Distributed Acoustic Sensors (DAS) for shallow ground characterization alongside railways [...]
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Monitoring of Tunnels in Urban Environments Complementing InSAR with in-situ Ground Instrumentation
H. Cabrera, U. Lobón, S. Palanisamy*, A. Batalla, D. Albiol, M. Camafort, L. Bento, N. Devanthery

ISC2024.

Abstract
One of the challenges in urban tunnelling projects is to guarantee that the infrastructure assets crossing or adjacent to the tunnel alignment and other new build elements are not affected by the construction activity. Radar Satellite Interferometry (InSAR) is a non-invasive surveying technique which provides millimetric deformation measurements of terrain structures over wide areas without any need to access site. This technique allows a comprehensive and periodic vision, with the same accuracy as manual levelling in cities for a fraction of the cost of traditional systems. ATLAS is the Sixense’s InSAR processing chain, aimed to monitor the different tunnelling activities phases: access shaft excavation, tunnel construction and settlement. This study focuses on real data obtained by Sixense during the monitoring of urban tunnel construction work in three major projects in London (UK) and Porto (Portugal), using a combination of technologies: InSAR for remote monitoring and two topographic instrumentation methods: Topographic Control Prisms through measurements with Robotic Total Station and Topographic Levelling. The methodology employed integrated InSAR to obtain surface deformation data across the tunnel influence zone and on-site instrumentation for detailed and precise measurements. Its implementation enabled continuous monitoring, revealing accurate and real-time deformation patterns near the tunnels. The results demonstrated a significant correlation between InSAR data and on-site measurements, validating the effectiveness of this combination.
Abstract
One of the challenges in urban tunnelling projects is to guarantee that the infrastructure assets crossing or adjacent to the tunnel alignment and other new build elements [...]
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Delivery added value using field measurements through the application of the Observational Method
H. Liew*, J. Marti, A. O'Brien

ISC2024.

Abstract
High Speed Two (HS2) is the new high-speed railway line in the UK currently being constructed between London and Birmingham. The designs of many HS2 retaining structures, as can be the case for some projects in the UK, were progressed concurrently with ground investigation. In this situation, to manage uncertainties in the ground, a cautious assessment of ground parameters was usually adopted. The purpose of field monitoring varies depending on the responsible or interested party. For designers, the primary aim is usually for design verification of their permanent works design. This paper describes how field observations, particularly quality instrumentation and monitoring data, were used at HS2 Bromford Tunnel East Portal to improve the existing design as construction progressed to create savings. To improve the efficiency in data processing, DAARWIN, a machine learning-based technology was used. The design and construction of the eastern end of the Bromford Tunnel East Portal were modified by eliminating the requirements of temporary support using measured field data, site observations and a carefully controlled construction through the application of the Observational Method. The portal construction programme was shortened by at least two weeks despite only three of the remaining temporary steel props being omitted. The findings revealed opportunities to extend the application of the Observational Method on adjacent structures including Bromford Tunnel West Portal and Washwood Heath Retained Cut. Given the great length of retained excavations of the two structures, the potential efficiency gains in cost, time and carbon emissions are significant whilst enhancing safety.
Abstract
High Speed Two (HS2) is the new high-speed railway line in the UK currently being constructed between London and Birmingham. The designs of many HS2 retaining structures, [...]
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Crossing a Landslide Area by a Motorway
N. Pinyol*, G. Di Carluccio, J. Moya, J. Bertrand, E. Alonso

ISC2024.

Abstract
A 1.5 km long stretch of a motorway built at midheigt of a valley eroded by an intermittent river, was almost completed in 2009. Budgetary restrictions led to a halt in construction. In the period 2009-2018, the motorway experienced severe damage, concentrated in three tributary shallow valleys, where the motorway was supported by compacted soil embankments. The “valleys” were, in fact, ancient landslides reactivated by the weight embankment of the embankment. The damaged embankments were substituted by bridges supported by pile foundations designed to resist the thrust of the active landslides. The bridges were completed by pile walls to improve the stability of the landslides. The construction of the wide roadway platform (40 m) required excavations at the mountainside, embankments at the riverside, additional stabilizing measures by anchored resisting walls, and systematic drainage. The miocene substratum is an irregular and heterogeneous set of conglomerate, sandstone, and claystone layers dipping 15-25º towards the river. The bedrock is covered by discontinuous quaternary clay and gravel formations. The paper describes: a) The singular sheared surfaces with very low friction, located in claystones, which were responsible for the instabilities observed; they played a key role in designing the stabilizing measures; b) The complex water pressure distribution and its variability in time, a consequence of the geological structure of substratum and the procedure designed to reduce pore water pressures and c) The difficulties encountered to install permanent high capacity anchors and the evolution of anchoring loads.
Abstract
A 1.5 km long stretch of a motorway built at midheigt of a valley eroded by an intermittent river, was almost completed in 2009. Budgetary restrictions led to a halt in construction. [...]
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Preliminary tests on the UAV-enabled installation of wireless sensors for monitoring inaccessible slopes
J. Gili*, M. Janeras, V. Salinas, O. Pedraza, A. Lluch, R. Carballo

ISC2024.

Abstract
Although remote sensing techniques (TLS, DPS) are useful for monitoring wide areas with diffuse hazard, the deployment of sensors in contact with the ground (slopes, cliffs, rock blocks) is mandatory when a focused mechanism is underway. So far, most of the so-called ‘geotechnical sensors’ (tiltmeters, jointmeters, stress sensors), and some surveying systems or accessories (like prisms, targets, GNSS receivers), must be installed manually on the landslide body. Furthermore, in some cases cables for the power supply and data collection are needed. Besides the technical difficulties, in some scenarios this installation phase may imply a high risk for the operators. To overcome this issue, in the contribution we present some test carried out with wireless sensors installed by means of Uncrewed Aerial Vehicle (UAV). Concretely, we deployed several wireless precision tiltmeters, able to acquire several measures per minute, and with LOng-RAnge communication capability. The experiments were developed in the frame of a risk mitigation project leaded by the ICGC in the Montserrat massif (near Barcelona, Spain), an area of paramount geomechanical and societal interest. There, the targeted instability mechanisms are medium and large rockfalls. The preliminary tests show that the installation of sensors with UAV can be of great help in the aforementioned situations. The UAV-enabled deployment method should be considered to speed up the availability of real time monitoring data.
Abstract
Although remote sensing techniques (TLS, DPS) are useful for monitoring wide areas with diffuse hazard, the deployment of sensors in contact with the ground (slopes, cliffs, [...]
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Using Combined Geotechnical and Geophysical Methods for Site Characterization of Ultra-Shallow Submerged Sites
N. Stark*, M. Gardner, A. Lemnitzer

ISC2024.

Abstract
Ultra-shallow underwater environments (average water depth ≲ 1 meters) in rivers, estuaries, and coastal zones represent the transition between water bodies and landmasses relevant for many engineering applications including utilities and transportation, habitat monitoring and restoration, and resilience to extreme flood and coastal storm events. With climatic shifts and an increased occurrence of extreme events, ultra-shallow underwater environments and inundation zones receive increasing attention. However, the increasing need for data revealed current limitations in safe accessibility and survey methodologies suitable for those conditions. Adaptation of geotechnical testing methods such as cone penetrometer testing and free fall penetrometer testing enable updated geotechnical testing capabilities, but these methods still require physical access to the measuring site which may be compromised by significant flow conditions, unknown debris and bottom conditions, limitations in access points and time, and combinations thereof. Remote sensing using optic sensors from unmanned aerial vehicles as well as from satellites offer strategies of soil classification in a rapid manner and without need for physical access if water conditions are clear. Advances in geoacoustic surveying, particularly regarding the use of sonars in ultra-shallow environments offers seabed surveying even in murky waters. Fusing geoacoustic and/or optic data with geotechnical point measurements enables the optimization of data collection in ultrashallow underwater environments or inundation zones in a safe and efficient manner, contributing also to available data from these environments to advance our understanding of soil mechanics in inundation zones and ultra-shallow waters. Here, an overview of available methods and recent advances in methodologies is presented supported by case studies including riverine and coastal environments.
Abstract
Ultra-shallow underwater environments (average water depth ≲ 1 meters) in rivers, estuaries, and coastal zones represent the transition between water bodies and landmasses [...]
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Ambient Seismic Noise Imaging for Tailings Storage Facilities Monitoring: a Benchmark between Accelerometers and DAS
L. Vivin*, C. Vulpe, L. McNab, A. Fourie, J. Boshoff, C. Cai, T. Allemand, T. Bardainne, J. Lepine, N. Lester

ISC2024.

Abstract
Recent examples of tailings dam failure remind us how the monitoring of such sites is important. One major factor affecting the stability of tailings storage facilities (TSFs) is the presence and movement of water within the facility. Dam failures are often caused by seepage or the presence of weak layers within the tailings dam or the foundation soil. Thus, monitoring for the presence or movement of water within TSFs is becoming increasingly important, and solutions for permanent, non-intrusive and cost-effective monitoring of dams are a major challenge. One such solution is represented by geophysical imaging techniques such as ambient seismic noise interferometry. Through a research project, a nodal network system of accelerometer sensors was installed in a dense and random array on a TSF embankment wall at an Australian mine. Simultaneously, a fiber optic cable was deployed in a trench at the top of the TSF. Ambient seismic noise was recorded over a few weeks using the nodal network and with the fiber optic cable over several months using Distributed Acoustic Sensing (DAS) technology. Following data acquisition, benchmarking passive seismic imaging from the accelerometer network and the DAS system was conducted to evaluate the DAS capabilities for long-term TSF monitoring.
Abstract
Recent examples of tailings dam failure remind us how the monitoring of such sites is important. One major factor affecting the stability of tailings storage facilities (TSFs) [...]
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Combining Remote Sensing Techniques to Optimize Digital Surface Models for Change Detection – A Case Study at a Pit Wall in the Canadian Cordillera
T. Gierc*, R. Macciotta, F. Liu

ISC2024.

Abstract
Slope monitoring is vital for open pit mines during operations and nearing closure where pit wall instabilities are present. Change detection using terrestrial laser scanning (TLS) has become part of the state of practice for collecting accurate measurements with extensive spatial coverage. The approach can detect displacements associated with global slope movement, as well as surficial occurrences such as rockfalls and sloughs. However, TLS acquisition quality is vulnerable to atmospheric interference and reflectivity of the target materials. In this regard, the high-density surface information obtained from TLS could be complemented with other, less detailed, remote sensing information in order to construct a complete surface model. Such an approach, however, requires a systematic workflow and a means to calculate surface model reliability. The subject of this study is an unstable pit wall at an open pit coal mine transitioning to closure. The site is located in the Canadian Cordillera, in a setting with intermittent fog and cloud cover, wildfire haze, and seepage within the slope face and toe. Insufficient TLS data can be obtained in local areas of the slope impacted by these conditions, as well as in shadowed areas on the benches above the TLS base elevation. Aerial photogrammetry was undertaken using UAV and combined with the TLS scan to generate a representative surface model. This paper presents a methodology for registration improvement between the TLS and UAV photogrammetry clouds, and evaluation of the combined surface using concepts of Limit of Detection (LOD) adopted from change detection techniques.
Abstract
Slope monitoring is vital for open pit mines during operations and nearing closure where pit wall instabilities are present. Change detection using terrestrial laser scanning [...]
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Piezometers: a very important instrument to which we need to pay more attention
J. Raventos*

ISC2024.

Abstract
Piezometers are instruments that can produce high-quality information if suitable and effective installation and monitoring procedures are followed. In order to minimise errors and optimise quality of the obtained information, we must pay attention when prescribing the type of piezometer and its installation, as highlighted in the ISO/EN18674 standards. The use of piezometers as a geotechnical instrument is a commodity. This paper aims to exemplify how the use of piezometers can be optimised and how the most common errors can be avoided.
Abstract
Piezometers are instruments that can produce high-quality information if suitable and effective installation and monitoring procedures are followed. In order to minimise errors [...]
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Revealing Structures below Vegetation using UAV-BASED LIDAR
M. Horn*, M. Seitz

ISC2024.

Abstract
LiDAR has been used for the last decade to create digital terrain models using Airborne Laser Scans (ALS) with about 10 points per square metre, mainly depending on flight altitude and speed. The data is used to produce elevation maps or digital surface models, calculate volumes and analyse the Earth's surface or objects above it. However, the resolution and elevation accuracy of about ± 0.3 m means that calculations are only estimates and ground features may not be identified. Unmanned aerial vehicle based LiDAR systems have some advantages over ALS data. Their lower altitude and speed allow the scanner to generate more points per square metre than an ALS. The more laser beams the scanner emits into the same area, the more beams pass through the vegetation and generate more points on the ground or other objects. This increases the level of detail in the digital terrain model. Reference points are another way of increasing the accuracy of the LiDAR scan. These points are placed within the survey area and have known coordinates and elevations to control and fit the result of the LiDAR scan to the coordinate system of the reference points. This data can be used for higher accuracy volume calculations and changes in the terrain structure (e.g. geological changes). Because the terrain is mapped at a high level of detail, it can also be used in explosive ordnance disposal to reveal hidden features such as trenches or bomb craters that may cause a problem for the project.
Abstract
LiDAR has been used for the last decade to create digital terrain models using Airborne Laser Scans (ALS) with about 10 points per square metre, mainly depending on flight [...]
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Event detection system for monitoring the cliff retreat and undermining of Castellfollit de la Roca village
M. Navarro*, M. Janeras, T. Carbonell, J. Pérez

ISC2024.

Abstract
Castellfollit de la Roca village (Catalonia, NE of Spain) stands on top of a basaltic cliff affected by rockfalls that are causing the retreat of the slope and the risk of undermining the buildings. So far, remote sensing techniques have been applied. They have detected centimetric precursory movements of toppling in basaltic columns, and unnoticed rockfalls of tiny volume as well. However, rockfalls of remarkable magnitude caused by other mechanisms have occurred at the foundation level of some houses, without any precursor movement detected by remote sensing techniques. In order to gather information from these events, a priority sector has been instrumented with a geotechnical network of crackmeters, tiltmeters and thermistors to monitor the thermo-mechanical behavior of the rock mass. Readings from the sensors have been automated through a wireless network based on Loadsensing nodes and gateway connected by LoRa technology. Tiltmeters are all-in-one devices of sensor and logger operating in dynamic mode. This system enables the detection of events and sending alert messages in real time. To receive reliable alerts for risk management, suitable thresholds have to be defined, based on the knowledge of the studied phenomena at the particular scenario. This paper presents the system set up and the threshold analysis through the observation of the cliff behavior on the daily and seasonal cycles registered during the first year of operation.
Abstract
Castellfollit de la Roca village (Catalonia, NE of Spain) stands on top of a basaltic cliff affected by rockfalls that are causing the retreat of the slope and the risk of [...]
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In-situ Characterization of Strength and Small-strain Stiffness in a Weathered Mudstone Profile
K. Briggs*, Y. Trinidad Gonzalez, G. Meijer, W. Powrie, N. Sartain, S. Butler

ISC2024.

Abstract
The weathering profile in mudstone outcrops can range from weathered clay to unweathered mudstone. The strength and small-strain stiffness of these materials, and of stiff clays and weak rocks in general, is critical to the design of geotechnical structures. Monitoring data and ground investigation data were gathered during the construction of a trial embankment founded on weathered, Jurassic-aged mudstone, for the HS2 high-speed railway project (UK). These data included outputs from in-situ downhole geophysical tests and extensometers at the embankment location. These were compared to ground investigation data from the wider mudstone outcrop over an 18.2 km stretch of the route. The installation of extensometers prior to loading by the embankment construction enabled the measurement of in-situ strains for a range of small and medium strains. It was therefore possible to characterise the stress-strain behaviour of the individual layers within the ground profile. The results showed that stiff clays derived from weathered mudstone at shallow depth (300 kPa) and higher maximum stiffness than the overlying clay. Both the strength and stiffness profiles showed a transition zone between the weathered clay and the unweathered mudstone. This zone included a partially weathered mudstone that had the visual appearance and index properties of a mudstone, but the strength of a stiff clay (i.e. τu < 300 kPa).
Abstract
The weathering profile in mudstone outcrops can range from weathered clay to unweathered mudstone. The strength and small-strain stiffness of these materials, and of stiff [...]
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Installation of Load Cells in Ground Anchors
E. Aceñero, T. Laqué*, Ó. Pérez

ISC2024.

Abstract
Load cells are used to measure tension (kN, tonne-force) in ground anchors and tendons in pre- or post-tensioned structures. Before installing and commissioning, it is strictly necessary to know the characteristics of the anchors to control as well as the installation and service scenery. Although it may look a simple assignment, there are several issues before supplying and installing a load cell: geometry of the anchor head, measurement range, expected precision, type of output signal and data transmission, temperature variations in the structure, and foreseen service life. The sort of tensioning jack and load steps are additional, unavoidable points to consider. By installing a load cell on a tieback, this is transformed into a measurement element, helping to understand the performance of the anchor as well as that of the surrounding area, medium- and long-term. To ensure load cells’ values are correct, we must take extra care with installation. Otherwise, the outcome will be flawed, and it will lead to erroneous conclusions and actions, with the subsequent increase in risk and money loss. In this paper, we share our experience regarding design, installation, and follow-up of load cells as elements to monitor the behaviour of anchored and post-tensioned structures and their area of influence
Abstract
Load cells are used to measure tension (kN, tonne-force) in ground anchors and tendons in pre- or post-tensioned structures. Before installing and commissioning, it is strictly [...]
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A Soil Base Model of Adjacent Various Story Structures
O. Samorodov, S. Tabachnikov*

ISC2024.

Abstract
The paper proposes an improved soil base model in the form of a continuous layer of finite distribution capability to simulate and calculate adjacent multistory structures in the base - foundations - structures system using powerful calculation packages such as SOFiSTiK, ABAQUS, PLAXIS, SCAD, Lira and others. The improved model considers the parameters of the stress-strain properties of the soils of the bases, the geometric profile taking account of the distribution capability of the base and different boundary conditions, but differs from the existing models in that it has a stepped geometric profile at the lower boundary of the model because of different compressible layer depths under each foundation of the structures. The use of this model improves the accuracy of simulating a soil base for large-sized foundations of adjacent structures to obtain reliable results of the stress-strain state of the base - foundations - structures system. An example demonstrates how to simulate and calculate raft foundations of a two-section multistory building in the base - foundations - structures system that interacts with an improved soil base model (linear strains of soils under loads are considered here) with reference to different numbers of stories of the sections. The numerical study results show on a specific calculation example that considering different compressible layers depths in the model under differently loaded foundations results in an increase in moment forces of up to 65% as compared with simulating the whole compressible layer, which may lead to the disruption of large-sized raft foundations.
Abstract
The paper proposes an improved soil base model in the form of a continuous layer of finite distribution capability to simulate and calculate adjacent multistory structures [...]
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Reliability-based Assessment of Deep Cement Mixing Column Based on Core Strength
T. Namikawa*

ISC2024.

Abstract
In the quality assurance procedure of the deep cement mixing method, the statistical parameters of the unconfined compressive strength of core samples, core strength, are adopted to assess the quality of the cement-treated soil ground. Since the statistical parameters of the core strength are the sample statistical parameters, the statistical uncertainty emerges when estimating the population parameters. Moreover, the spatial correlation of the core strength should be considered on the evaluation of the overall strength of cement-treated soil ground. The paper presents a reliability-based assessment for the deep cement mixing soil column based on the core strength. The analysis method in which the statistical uncertainty included in the core strength and the spatial variability of the strength are considered simultaneously is adopted to calculate the overall failure probability of the cement-treated soil column. The statistical uncertainty is estimated using a Bayesian inference method and the random fields of the strength are generated with the statistical parameters involving the statistical uncertainty. The random finite element method with the generated random fields is performed to simulate the compression failure behaviour of a cement-treated soil column. The analysis result provides the cumulative distribution function of the overall strength of the cement-treated soil column. The reliability-based assessment is performed on the basis of the cumulative distribution function of the overall strength.
Abstract
In the quality assurance procedure of the deep cement mixing method, the statistical parameters of the unconfined compressive strength of core samples, core strength, are [...]
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Towards the development of a standard for the PS suspension logger
R. Hen-Jones, G. Comber, P. Worthington, S. Garantini, R. Buckley*, I. Jones

ISC2024.

Abstract
The PS logger is a well-established seismic tool for measuring P and S wave velocities in a single borehole, using low frequency indirect excitation originating from a dipole source. Because of its low operating frequency, it is capable of generating seismic waves in slow, unconsolidated materials such as those found in offshore environments where S wave velocity is often used to estimate the small strain stiffness, Gmax (of particular interest to offshore construction). Despite its widespread use, there is no current standard for the use of the PS logger, even though other methods operating on similar principles have well-established reference methodologies and guidelines. As such, PS logger methodology is largely dictated by user manuals written by manufacturers, which likely introduces inconsistencies in operation guidelines, and may impede consistency in data obtained by different users. In this paper, the authors conduct a literature review of existing standards for relevant methods including CPT, SPT, SCPT and downhole and crosshole seismic testing, as well as relevant ground investigation standards, identifying the need for standardisation of the PS logging method. Examination of the current state of standardisation concludes that although existing seismic testing standards could possibly be expanded to include the PS logging method, the differing constraints and operational requirements are such that the development of a specific PS logger testing standard is highly recommended. An initial framework is presented for a PS logger standard, identifying the required components, in terms of borehole requirements, testing procedure, data interpretation and best practice.
Abstract
The PS logger is a well-established seismic tool for measuring P and S wave velocities in a single borehole, using low frequency indirect excitation originating from a dipole [...]
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Development of international standard on the use of geotechnical instrumentation under the ISO umbrella
J. Raventos*

ISC2024.

Abstract
International standards for monitoring under ISO have been under development since 2010 and the intentions were presented during the 8th International Symposium on Field Monitoring in Geomechanics (FMGM 2011) in Berlin. Progress on this project was reported at FMGM 2015 in Sydney and ISFMG 2022 in London. The base standard on general rules was published in 2015, part 2, the standard on extensometers, in 2016 and in 2017 the third part on inclinometers. Part 4 on piezometers was published in 2020, Part 5 on pressure cells in 2019 and Part 8 on load cells in 2023. These standards have been published as ISO Standards in English and French worldwide. In Europe the standards have been published under EN ISO 18674 member countries of CEN have to publish these standards in their country. The standards on settlement measurements by hydraulic systems (part 6), geodetic measurements (part 9) and strain measurement (part 7) are under development and will be submitted to enquiry in the next few months.
Abstract
International standards for monitoring under ISO have been under development since 2010 and the intentions were presented during the 8th International Symposium on Field Monitoring [...]
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Impact of Damping Boundaries on the Quality of the Output Signal in Bender Element Experiments
M. Roshan, D. Bendea, I. Moldovan*, M. Martins, M. Pultorak, A. Gomes Correia, M. Azenha

ISC2024.

Abstract
Bender elements are a popular experimental device for the measurement of the small strain shear modulus of geomaterials. Bender elements are easy to use, can be easily installed in most geotechnical devices (e.g., triaxial apparatus, oedometers, and Rowe cells), and yield shear modulus readings that compare well with those obtained from resonant column tests. Typically, bender element tests involve inducing a shear wave at one end of a sample (the input signal) and reading its arrival at the other end (the output signal). However, the wave propagation induced by bender elements is complex, hindering the interpretation of the output signal and inducing considerable uncertainty in the shear modulus readings. Indeed, besides the desirable shear wave, the vibration of the transmitter also generates laterally propagating compression waves, which reflect from the lateral envelope back into the sample and pollute the output signal. This study analyses the effect of lateral boundaries especially conceived to dampen the incoming compression waves on the quality of the output signal. In this context, damping moulds are designed based on computational simulations of the transient dynamics of the wave propagation, to promote an output signal that presents a clearly identifiable arrival of the shear wave, without it being concealed by compression wave pollution. Prototypes of a few promising designs are produced using 3D printing and tested in the laboratory using a benchmark material (Toyoura sand) and a range of input frequencies. The results are compared with those obtained in a conventional setup with no damping moulds.
Abstract
Bender elements are a popular experimental device for the measurement of the small strain shear modulus of geomaterials. Bender elements are easy to use, can be easily installed [...]
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Use of Elastic Full Waveform Inversion for Monitoring of Dams and Levees
J. Montgomery*, J. Coe, P. Alidoust

ISC2024.

Abstract
Understanding subsurface conditions is critical to creating and maintaining resilient infrastructure systems, such as dams and levees. Seismic geophysical tools can be very effective for site characterization of these structures as they directly measure the elastic moduli and can provide insight into both the soil properties and groundwater conditions. Full waveform inversion (FWI) is one processing option for seismic geophysics that seeks to overcome some of the limitations in the traditional approaches by using the full time-domain recording of the wavefield to develop 2D or 3D profiles of shear wave velocity. In addition to providing characterization data, FWI can also potentially be used as a monitoring tool for dams and levees to assess how elastic moduli are changing with time and to infer how these changes might relate to changes in the hydromechanical properties of the soil. This study seeks to explore the use of seismic FWI as both a characterization and monitoring tool through numerical simulations of seismic surveys on a hypothetical levee with a low velocity anomaly in the foundation. The simulations are used to assess both the spatial resolution and the ability of the simulations to detect changes in properties that might be related to softening of the foundation or development of internal erosion failure modes. The findings from the study will be used to highlight potential benefits and challenges to using seismic FWI for characterization and monitoring of dams and levees.
Abstract
Understanding subsurface conditions is critical to creating and maintaining resilient infrastructure systems, such as dams and levees. Seismic geophysical tools can be very [...]
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Impoundment characterisation for hydraulic mining of tailings
C. Morales*, A. Sfriso

ISC2024.

Abstract
Reprocessing old tailings storage facilities (TSFs) has become increasingly common in the past ten years because of economic, environmental, and social reasons. Tailings deposited by spigots experience segregation and layering, creating deposits that are difficult to excavate due to the highly erratic geotechnical behaviour of the exposed faces. Both in-situ and laboratory testing are necessary to understand how steep, temporary tailings slopes might behave, ensuring stability through engineering analysis. This paper describes a detailed geotechnical characterization of an old TSF impoundment by in situ and laboratory testing, including sonic drilling, SCPTu soundings, geophysical field testing, and oedometric, monotonic and cyclic triaxial lab testing. Two different areas were surveyed: tailings near the dam, where coarser material is expected, and in the centre of the impoundment for the characterization of finer materials. We focused on the critical state behaviour of tailings and estimations of the state parameter, required to calibrate the numerical models employed in the analyses.
Abstract
Reprocessing old tailings storage facilities (TSFs) has become increasingly common in the past ten years because of economic, environmental, and social reasons. Tailings deposited [...]
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Determination of the S-wave propagation velocity of ballast by Spectral Analysis of Surface Waves
R. Ruiz Bravo, J. Estaire Gepp, Á. Tijera Carrión*, M. Santana Ruiz de Arbulo

ISC2024.

Abstract
The Laboratorio de Geotecnia-CEDEX uses some software and tools for studying different phenomena and performance of track sections. For this purpose, it is usually necessary to determine the S-wave (shear elastic wave) velocity of the different layers in the track section which typically are, from bottom to top: natural ground, embankment, form layer, subballast and ballast. The Laboratorio de Geotecnia-CEDEX has experimental S-wave propagation velocity (Vs) values of embankments, form layers and sub-ballast layers, obtained from several campaigns where the Spectral Analysis of Surface Waves (SASW) was applied on the different layers during the construction of several track sections. To complete the studies and to obtain Vs values for the ballast layer, two campaigns were carried out in the CEDEX Track Box (CTB), a railway testing facility where it is possible to test complete railway sections on a 1:1 scale; and a field measurement campaign on an in-service railway track. Due to the discontinuous nature of the ballast layer carrying out tests to obtain Vs presents serious problems. To avoid these problems, a new procedure was developed to obtain these values using the SASW method by installing sensors on top of the sleepers. Through the interpretation of measurements taken with the SASW technique on the ballast, the dispersion curve is obtained, and from it, the values of Vs are calculated. The results are presented in this article and are also compared with values found through a literature review obtained or estimated by other authors.
Abstract
The Laboratorio de Geotecnia-CEDEX uses some software and tools for studying different phenomena and performance of track sections. For this purpose, it is usually necessary [...]
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Dynamic Response of Marginal Soil using SPT, DCPT & Cyclic Simple Shear Tests
S. Dutta*, A. Sachan

ISC2024.

Abstract
Coarse-grained soils are preferably used in geotechnical infrastructure projects such as retaining walls and highway embankments due to their superior drainage and frictional properties. However, such materials are not always available on or near the construction site. Given the limited availability, high cost, and transportation issues associated with coarsegrained fill, using the locally available marginal soil for the various infrastructure projects becomes essential. Marginal soils are soils with a high percentage of fines that can be cohesive or non-cohesive. The primary concern with marginal soil is its low permeability, which causes excess positive-pore water pressure evolution during load application. As a consequence, the soil loses shear strength over time. Previous researchers have provided some information on the dynamic behaviour of marginal soils in terms of cyclic strength and pore pressure development. However, more research is needed to understand the dynamic response of compacted marginal soils in terms of cyclic resistance ratio (CRR) using field and lab data. Therefore, an attempt has been made in this study to evaluate the cyclic resistance of compacted marginal soil (clayey sand) by performing stress-controlled cyclic simple shear (CSS) tests in the laboratory and Standard Penetration Test (SPT) and Dynamic Cone Penetration Test (DCPT) in the field. The cyclic strength of marginal soil has been determined as Cyclic Resistance Ratio (CRR) by using laboratory (CSS) and field (SPT, DCPT) test data.
Abstract
Coarse-grained soils are preferably used in geotechnical infrastructure projects such as retaining walls and highway embankments due to their superior drainage and frictional [...]
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Improved Modeling and Inversion of Surface Wave Method
T. Wu*, C. Lin, Q. Tran, E. Pan

ISC2024.

Abstract
The multi-channel analysis of surface waves (MASW) is a widely employed surface wave method. The fundamental mode inversion is the usual scheme in MASW, because separating the fundamental mode from other high modes is feasible with an adequately long array. However, the extracted fundamental mode represents only part of the dynamic characteristics, it may deviate from the theoretical fundamental mode due to truncation effect, and part of it may correspond to another higher mode or leaky mode, resulting in mode misidentification. Conversely, the spectral analysis of surface waves (SASW) method features a more rigorous inversion scheme by matching the effective mode, but it may suffer from the tricky phase-unwrapping in the dispersion data reduction. This study introduces an improved dynamic response solution for elastic-layered media subjected to vertical loads. The proposed dynamic response solution is fast and accurate, facilitating the full wavefield inversion in terms of the frequency-velocity spectrum. The MASW frequencyvelocity spectrum inversion considers testing configuration and comprehensively models all wave phenomena, including near-field effect, truncation effect, and leaky waves. The MASW frequency-velocity spectrum inversion merges the convenience of MASW dispersion analysis with the rigorous inversion scheme adopted by SASW. The new MASW frequency-velocity spectrum inversion is compared with the SASW effective mode inversion and MASW fundamental mode inversion. The results show that both SASW effective mode inversion and MASW frequency-velocity spectrum inversion produce better inverted results than the MASW fundamental mode inversion, while the process of MASW frequency-velocity spectrum inversion is more convenient and robust. Finally, a field example is used to demonstrate the applicability of frequency-velocity spectrum inversion.
Abstract
The multi-channel analysis of surface waves (MASW) is a widely employed surface wave method. The fundamental mode inversion is the usual scheme in MASW, because separating [...]
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The Next Generation of Testing with LWD to Assess the In-Situ Permanent Deformation of Geomaterials under Repeated Loading
D. Kuttah*

ISC2024.

Abstract
This study focuses on evaluating in-situ permanent deformation in fine-grained soils through the application of a specially designed Repeated Light Weight Deflectometer (LWD) test. The primary objective is to investigate how water content and applied stress levels influence permanent deformations in the field. Additionally, the study aims to assess the utility of LWD-derived data in predicting permanent strains. Results indicate a significant correlation between permanent deformations and key parameters, such as the number of load cycles, applied stress levels, and water content. It is observed that permanent deformations increase proportionally with these variables, particularly in cases of elevated water content and higher stress levels. The soil demonstrates an increased susceptibility to accumulating permanent deformations, persisting even after numerous LWD load applications. In response to these findings, a predictive model is presented to estimate accumulated permanent strain, exhibiting a commendable fit to data for moisture contents up to 22%, corresponding to an average water content of 19%. Ultimately, this research underscores the pivotal role of water content and applied stress levels in determining permanent deformation characteristics in fine-grained subgrade soils. The study also provides a valuable predictive model derived from repeated in-situ LWD measurements, offering critical insights into the field permanent deformation behaviour of subgrade soil. This simple and time-saving test enhances engineering practices for pavement design and construction.
Abstract
This study focuses on evaluating in-situ permanent deformation in fine-grained soils through the application of a specially designed Repeated Light Weight Deflectometer (LWD) [...]
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Model CPTs in Chalk
T. Riccio*, M. Previtali, M. Ciantia, M. Brown

ISC2024.

Abstract
Cemented geomaterials exist in many parts of the world. Structure and bonding largely influence their strength, stiffness, permeability and other hydromechanical properties. Despite the CPT being the most widely used geotechnical engineering soil characterization tool, most existing correlations between penetration resistance and soil parameters apply only to uncemented granular deposits. Application of existing correlations to cemented geomaterials such as soft rocks can produce misleading interpretation making CPT application more challenging. In particular, CPT databases correlating tip resistance with yield stress of the intact material show a wide scatter prompting the need for a better understanding of the mechanics of cone penetration in soft bonded materials. In this work, 1g small-scale model CPTs are performed in a soft rock, whilst in-test X-ray techniques help to reveal mechanisms behind the penetration process. Thereafter, experimental results are compared to field scale results and those modelled using the Particle Finite Element method which is geared toward large deformation analyses. The combined interpretation of the experimental and numerical data is then used to discuss some of the unique attributes of CPT behaviour in soft rock.
Abstract
Cemented geomaterials exist in many parts of the world. Structure and bonding largely influence their strength, stiffness, permeability and other hydromechanical properties. [...]
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Improving the reliability of sand-steel interface friction angle measurements based on the Ring Shear test
A. Almukashfi*, S. Larsen, N. Katic

ISC2024.

Abstract
Understanding the shearing behaviour at soil-structure interfaces is crucial for the analysis and design of geotechnical structures. When significant relative displacements between soil and interface are involved during installation or operation, the ring shear interface testing method, which includes large pre-shearing, is considered reliable for assessing interface resistance. These tests are commonly applied in practical design approaches for driven piles. This research aimed to expand the unified database created by Imperial College London (ICL) and Norwegian Geotechnical Institute (NGI) by incorporating soil test data collected by Geo for North Sea sands with varying grain size distributions. We present an extended database that encompasses soil classification tests and Ring Shear (RS) tests conducted on soilsteel interfaces using Advanced Ring Shear apparatus (Bishop-apparatus-like). This paper introduces a database of interface shearing tests conducted on sandy silty soils with a low content of non-plastic fines. These results facilitate a comprehensive examination of the potential impacts of various factors, including physical soil properties (e.g. grain size distribution), interface characteristics (surface roughness), and testing conditions (normal effective stress). Trends identified within the datasets are synthesized with insights from prior studies to propose interface shear strength parameters suitable for preliminary design employing simple index tests for non-plastic sandy soils. Finally, the paper presents a newly advanced Ring Shear apparatus designed by Wille Geotechnik capable of accommodating static friction. This apparatus incorporates two novel test inserts that can rotate independently at varying radial speeds while being guided simultaneously. The two guided rings can be vertically adjusted, thereby mitigating static friction effects, even in cases of dilatancy.
Abstract
Understanding the shearing behaviour at soil-structure interfaces is crucial for the analysis and design of geotechnical structures. When significant relative displacements [...]
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Gassy Soils ofF the Llobregat Delta: Impact on Geomechanical Characterization
D. Tarragó*, A. Gens, A. Deu

ISC2024.

Abstract
The presence of biogenic gas in the soft soils of the Delta del Llobregat at the Port of Barcelona has already been reported by various authors based on geophysical investigations and in-situ tests. As the impact of gas presence on soil behaviour remains uncertain, it is of interest to describe the behaviour of these gassy soils as they may affect future expansions of the Port of Barcelona. Recently, in new geotechnical investigations at the Port of Barcelona, gas emissions have been observed, in several locations in the vicinity of the South breakwater, while performing in situ tests (CPTu and SDMT) or during borehole drilling. Samples were extracted from those boreholes that were subsequently used for laboratory tests. Given the potential impact on geotechnical properties, the results of the investigation were utilized to increase the understanding of gassy soils. Essentially, the focus was on detecting anomalies in geotechnical parameters at the points where gas was detected. These anomalies were also correlated with observations of soil structure obtained from microCT scanning X-ray images of undisturbed samples from the zones where gas was present.
Abstract
The presence of biogenic gas in the soft soils of the Delta del Llobregat at the Port of Barcelona has already been reported by various authors based on geophysical investigations [...]
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Application of Physics-Informed Machine Learning to Geotechnical and Geophysical Site Investigation Data To Define Centimetre-Scale Design Parameters for Offshore Wind
H. Marin Moreno*, S. Gourvenec, J. Charles

ISC2024.

Abstract
Offshore wind plays a pivotal role in enhancing Europe's energy security and achieving energy decarbonization goals. However, expediting offshore wind deployment necessitates efficient and economical site investigation surveys. To address this challenge, we introduce a novel approach utilising a deep neural network (DNN) to establish correlations between geotechnical cone penetrometer test (CPT) data and shear wave velocity (ð) from seismic CPT. Subsequently, porosity and P-wave velocity (ð) are derived using a ð to bulk density correlation and a dynamic poroelastic model. The DNN is trained and tested on a dataset comprising 5284 instances of public-domain geotechnical CPT test data, including depth, tip resistance, sleeve friction, and ð from seismic CPT. During testing, the DNN model demonstrates a mean absolute error of 55 m s-1 between predicted and measured ð values. The uncertainty in ð predictions is attributed to factors such as (i) limited training data for some soil types such as gravelly sands, (ii) intricate relationship between geotechnical CPT features and seismic properties influencing ð, (iii) the presence of CPT features and ð combinations that lie well outside the region from most combinations (i.e. outliers), and (iv) CPT features and ð measurements that are averaged over different depth ranges. The derived porosity and ð
Abstract
Offshore wind plays a pivotal role in enhancing Europe's energy security and achieving energy decarbonization goals. However, expediting offshore wind deployment necessitates [...]
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Small Strain Shear Modulus Derived From Offshore Seismic Reflection Data
M. Murali, J. Peuchen, L. Sybrandy*, M. Vrolijk, V. Vandeweijer, S. Atkins, S. Carpentier, B. Boullenger

ISC2024.

Abstract
Small strain shear modulus ðº preferred reference method for ðº is an important parameter for design of foundations of fixed offshore structures. The is the seismic velocity test (SVT) performed as part of a seismic cone penetration test (SCPT). SVTs provide in-situ ðº values for discrete depth sections of SCPTs. This paper focusses on added value achieved by (1) generation of 15 million synthetic ðº (2) a ðº profiles to 50 m depth and zonation map for the IJmuiden Ver Wind Farm Sites Alpha and Beta (offshore Netherlands). The synthetic ðº profiles were derived from a data set of 51 SCPT profiles, 250 CPT profiles and 2D UHR seismic reflection traces along survey track lines spaced at about 70 m. The quality of the SCPT data and UHR seismic reflection data was stateof-the-art (as of 2021). The data process included the use of a (1) multi fidelity data fusion statistical framework and (2) machine learning by a convolutional neural network. The synthetic ðº data were the basis for the ðº zonation map used to enhance an integrated ground model for the wind farm sites. Particularly, the map can be used to quickly identify and constrain areas which are favourable and challenging for design of monopiles and other common foundation types typically considered for offshore wind turbines.
Abstract
Small strain shear modulus ðº preferred reference method for ðº is an important parameter for design of foundations of fixed offshore structures. The is the seismic [...]
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Linking multi-sensor core logger data with in-situ and laboratory testing: A North Sea case study
C. Bilici, S. Quinteros, S. Smith*, P. Gjerde

ISC2024.

Abstract
Driven by an increase in the scale of laboratory testing programs, the industry is looking for new methods of soil characterisation and ways to extract more benefit from existing data. In this paper, applications of Multi-Sensor Core Logging (MSCL) to site characterisation projects are discussed, highlighting the potential for providing a fast, quantitative assessment of recovered samples. Sensors of the MSCL include bulk density, P-wave velocity, natural gamma, electrical resistivity and magnetic susceptibility. Natural gamma is shown to be related to higher silt and clay content, acting as a useful parameter for soil classification and quantitative assessment of fines content. A comparison between MSCL and in-situ CPTu data reveals correlations between natural gamma and friction ratio, normalised soil behaviour index, Ic, and net pore pressure response. By collecting MSCL data on all samples at the beginning of a lab program, one can obtain a full overview of the material available for testing, leading to more strategic sample selection and a reduced overall volume of testing. Correlations with MSCL parameters and geotechnical properties can be used to predict continuous profiles, and be extended to in-situ measurements from borehole logging and CPT
Abstract
Driven by an increase in the scale of laboratory testing programs, the industry is looking for new methods of soil characterisation and ways to extract more benefit from existing [...]
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"Development and Preliminary Testing of a New Robotic Tool for Direct Determination of ‘P-Y’ Soil Reaction Curves for Offshore Geotechnical Applications"
A. El Hajjar, J. Creasey, E. Ibraim, A. Conn, G. Martin, A. Diambra, D. Igoe, D. White

ISC2024.

Abstract
Monopiles are the most widespread foundation option for offshore wind turbine foundations and their design is largely governed by lateral stability and serviceability. The determination of lateral soil reaction ‘p-y’ curves is a crucial element for their design. At present, ‘p-y’ curves are typically determined through indirect methods, such as correlation from fundamental constitutive parameters, CPT data or extracted through numerical procedures. This paper presents the specification requirements, initial mechanical design, sensor calibration and preliminary testing in a small calibration chamber of a new robotic site investigation tool, the ROBOCONE ‘p-y’ module. This new device can be fitted behind a standard CPT cone. It features a cylindrical module that, after insertion in the ground, can move sideways to closely mimic the kinematic mechanism experienced by a laterally loaded pile element and provide direct “in-situ” characterisation of the ‘p-y’ soil reaction curves. The imposed horizontal translation is substantially different from those of the typical pressuremeter and dilatometer, and analogous to that of a small laterally loaded pile. Movements of the module can be programmed to apply simple monotonic lateral loading conditions and complex stress-controlled or deformation-controlled histories (i.e. cyclic loading, consolidation stages, maintained load). These provide data that can be scaled directly to support advanced cyclic and whole-life design procedures for the lateral ‘p-y’ response of piles.
Abstract
Monopiles are the most widespread foundation option for offshore wind turbine foundations and their design is largely governed by lateral stability and serviceability. The [...]
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Pleistocene and early Holocene palaeo-landscapes of the Dogger Bank South Wind Farm Sites
M. van Cappelle*, L. Arlott, W. van Kesteren

ISC2024.

Abstract
A preliminary ground model was prepared for the planned Dogger Bank South Wind Farm Sites in the UK sector of the North Sea. This ground model is based on a geological interpretation of 2D Ultra Ultra High Resolution Seismic (UUHRS) data and geotechnical data. The interpretation results include seismostratigraphic horizons which delineate major soil units. Mapping of these soil units is important for the planning and design of wind turbine locations and inter array cables. Additionally, these horizons reveal (1) multiple generations of buried palaeochannels and (2) evidence for shifting coastlines. The buried palaeochannels have tributaries and contain evidence for the local presence of marshlands (peat beds) beyond the channel margins. These landscapes formed during the Pleistocene and were subsequently flooded when sea level rose as a result of meltwater release from rapidly decaying ice sheets. Locally, thick sequences of early Holocene marine sand deposits show evidence of large-scale clinoforms, which indicate that palaeocoastlines prograded seaward over a distance of up to 20 km during the early Holocene. The top of these clinoforms contain erosion surfaces and gravel lags, indicating sub-aerial exposure of the delta top. This shows that while in general ‘Doggerland’ was rapidly flooded during the early Holocene, there were short periods when the land area expanded.
Abstract
A preliminary ground model was prepared for the planned Dogger Bank South Wind Farm Sites in the UK sector of the North Sea. This ground model is based on a geological interpretation [...]
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Preliminary insights from Foundations for Offshore Wind Turbines (FRONTIErS) Doctoral Network
L. Prendergast*, K. Gavin, M. Arroyo, G. Eiksund

ISC2024.

Abstract
The European offshore wind sector has grown rapidly, with significant advances in turbine technologies, in creased sizes, and construction locations further from the shore in deeper waters than ever before. A critical challenge has emerged relating to a growing lack of knowledge surrounding how to design foundations to support these new turbines, with the safety, life-span, cost, and environmental implications coming increasingly into question. To maintain Europe’s stance as a World-leader in offshore wind, Foundations for Offshore Wind Turbines (FRONTIErS) Doctoral Network has been designed to bring together research-intensive universities and major industry stakeholders to train the next generation of graduates with the appropriate skills to tackle the emerging issues presenting as a barrier to continued development of the sector. Eleven Doctoral Candidates have been recruited to tackle significant challenges related to foundation design and performance. Projects focus on topics such as: understanding soil variability, effect of cyclic loading on axial capacity, pile aging, dynamic modelling informed from in-situ testing, time and spatial variation in soil properties, driveability modelling, gravity-base scour effects, multi-directional loading effects, centrifuge testing of cyclic loading response, and dynamic features of wind turbine foundations. This paper presents a preliminary overview of the various PhD projects ongoing as part of this network, which are in the early stages, as well as a summary of training conducted to date.
Abstract
The European offshore wind sector has grown rapidly, with significant advances in turbine technologies, in creased sizes, and construction locations further from the shore [...]
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The importance and influence of the interpretation of geological-geotechnical data on safety of earthen dams
T. Andrade, J. Fernandes, C. Honório, M. Neto, W. Fonseca, D. Eloi*

ISC2024.

Abstract
The geological-geotechnical investigation campaign plays a fundamental role in dam safety by providing essential information for assessing and managing the risks associated with these structures. It also allows potential problems to be identified, such as the presence of geological faults or unstable soils. This information allows preventive actions to be taken to avoid catastrophic collapses, through additional containment measures or the revision of the dam's design.The aim of this article is therefore to present the interpretation of the geological-geotechnical data (geophysical tests, Vane Test, triaxial tests, CPTu and mixed borehole) obtained from a robust campaign to investigate the structure of a sediment containment earth dam, raised downstream, located in the state of Minas Gerais. The use of these results meant that the structure could be evaluated with the real conditions of the terrain in different situations such as seismic or hydrostatic overloads, guaranteeing the stability of the structure. In addition, it was possible to determine the soil's capacity to withstand the loads exerted by the dammed water and identify possible points of fragility.From the results obtained in the analysis and interpretation of the structure's sections, it was possible to measure the influence of the discretization of the earth dam massif through the structure's stability analysis, which also made it possible to make a comparison with the analysis sections before and after the geological-geotechnical campaign. In addition, it was possible to discuss the importance and demonstrate that it is essential to carry out comprehensive and up-to-date geological-geotechnical investigation campaigns to ensure that dams are built and operated safely.
Abstract
The geological-geotechnical investigation campaign plays a fundamental role in dam safety by providing essential information for assessing and managing the risks associated [...]
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Post-liquefaction analysis and shear wave assessment by means of instrumented DCP: application to Cephalonia island (Greece) and Petrinja region (Croatia)
D. Moiriat, T. Luong*, P. Reiffsteck, M. Benz Navarrete, B. Mravlja, N. Belić, P. Rischette, N. Theodoulidis, B. Kordic, S. Markušić

ISC2024.

Abstract
This work presents both a summary of its implementation at two post-seismic sites: the island of Cephalonia (Greece), and the Petrinja (Croatia) along the Kupa river. In the first case, the main objective was to characterize the surface formations of the Koutavos plio-quaternary sedimentary basin to propose a 1D model of the surface soil column and assess the influence of the variability of these surface formations on the amplification of seismic motion. The second experimental campaign in Croatia was aimed at identifying the soil layers that had been liquefied following the events of 2020, as well as highlighting the different soil models obtained by geophysics or constructed from instrumented variableenergy DCP. For each investigated site, additional geophysical and geotechnical tests were carried out. The data collected with this new technology were compared with those obtained previously with other geophysical methods (MASW), in order to assess the shear wave velocity obtained in particular.
Abstract
This work presents both a summary of its implementation at two post-seismic sites: the island of Cephalonia (Greece), and the Petrinja (Croatia) along the Kupa river. In the [...]
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Geotechnical characterisation of tailing deposits with instrumented variable energy dynamic penetrometer: a state of art
S. Espinoza*, G. Villavicencio, G. Suazo, M. Benz, P. Breul, L. Teissier

ISC2024.

Abstract
Chile is the third country with most tailing dams worldwide (764, of which 15% active, 62% inactive, and 23% abandoned). Today, one of the main challenges of the mining industry is to ensure environmental sustainability. To achieve this, it is not only necessary to have regulations guaranteeing correct design, maintenance, closure stages, but also supervision and suitable technology enabling rapid, reliable, and cost-effective diagnosis of the overall tailings dam stability. For the last 20 years, French instrumented dynamic cone penetrometer, P.A.N.D.A®, has been used for in-depth quality control of tailings deposits, mainly due to its rapidity, portability, easy-to-use, cost-effective, and environmentally friendly testing which is based on standardized methods and able to produce immediate results. The last few years, different studies have been carried out to characterize tailings dams from a geotechnical perspective as well as to assess their spatial and temporal variability. This article presents a summary of the 20 years of Chilean experience in compaction quality control and geotechnical characterization of mine waste facilities using P.A.N.D.A® to assess the overall stability, slope analysis stability, liquefaction triggering, spatial variability of material properties and evaluation of some geotechnical parameters. Indeed, given the scale of the problem these structures represent for the community and the environment, it seemed necessary to bring together most of the work carried out in Chile to propose an innovative alternative to the rest of the mining community.
Abstract
Chile is the third country with most tailing dams worldwide (764, of which 15% active, 62% inactive, and 23% abandoned). Today, one of the main challenges of the mining industry [...]
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A review of 30 years French instrumented and variable energy dynamic cone penetrometer Panda
M. Benz Navarrete*, P. Breul, P. Moustan, G. Villavicencio Arancibia, L. Teissier

ISC2024.

Abstract
Dynamic penetrometer is a worldwide practice in geotechnical exploration and the French Panda (1) lightweight variable energy is the most developed device nowadays. Widely used in France and other countries, The Panda penetrometer is relatively unknown for characterizing surface soils domain and the possibilities it offers. In this article, the authors offer a brief review of the principle of measurement, its uses, advantages and disadvantages calibration, and interpretation, as well as the different relationships with other in-situ test (CPT, SPT…) and some geotechnical parameters. A summary of the works that can be found and that are based on this technology is also presented. The overall aim is to provide the reader with a basic historical document for a better understanding of the operation and analysis of the results obtained with this device, enabling it to be integrated, as a complement, into in situ investigation campaigns.
Abstract
Dynamic penetrometer is a worldwide practice in geotechnical exploration and the French Panda (1) lightweight variable energy is the most developed device nowadays. Widely [...]
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Ligthweigth and heavy-duty instrumented, servo assisted dynamic cone penetrometers for shallow soil characterisation
M. Benz Navarrete, P. Breul, Q. Tran*, C. Forestti, T. Luong

ISC2024.

Abstract
Based on the principle of the Panda® penetrometer, a third-generation of variable-energy dynamic cone penetrometer has been developed in France: the Panda 3(1). This is an instrumented dynamic penetrometer which, by measuring strain, acceleration, and displacement on the rods, close to the anvil, and then decoupling the deformation waves created by the impact and propagating within the rods during penetration, makes it possible to obtain for each blow, at the soil/cone interface, a dynamic load penetration curve, called DCLT curve. Several experimental and numerical studies have been carried out to develop different techniques for processing DCLT curves and dynamic signals to assess input energy, dynamic and pseudo static cone resistance, dynamic stiffness, elastic modulus, and compressional wave velocities of soil. This technique has been adapted to the DPSH cone penetrometer (ISO 22476-2), for which it was necessary to servoassisted the impact force as a function of the soil penetration obtained after each blow to improve then the quality of the signals and DCLT curves obtained. Recently, in France, a vast experimental program involving two universities and two geotechnical companies was carried out to develop this new technique. A large laboratory and in-situ test data base was performed. After a brief presentation of the theoretical and technological development of this new technique is presented.
Abstract
Based on the principle of the Panda® penetrometer, a third-generation of variable-energy dynamic cone penetrometer has been developed in France: the Panda 3(1). This is an [...]
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Application of Swedish Weight Sounding Test for the Geotechnical Assessment of Solar Power Plant
J. Gargullo*, R. Luna

ISC2024.

Abstract
As part of the global efforts to mitigate climate change and foster sustainable development, the construction of solar power plants has experienced significant growth in the Philippines over the past few years. This constitutes an increasing contribution to the renewable energy sector. This paper presents the applications of the Swedish Weight Sounding Test in the geotechnical assessment for solar power plant facilities. Utilizing SWST is a more portable and cost-effective way to evaluate the soil conditions crucial to establishing the solar panel arrays' foundation system and the project's overall feasibility. The penetration resistance data of SWST was employed to establish the soil stratification, soil strength, and consequently the foundation type and allowable bearing capacity. Moreover, the results were also used to assess the susceptibility of the project site to geohazards, such as liquefaction. Theoretical capacities of the helical and screw piles, the widely used foundation system for solar panels, can be derived and correlated with the results of the SWST. This paper shall present the utilization of SWST, as a supplement to SPT, primarily on the geohazard and foundation assessment for solar power plants. This study is expected to provide a reliable reference on the advantages of SWST and the selection of foundation type based on the results obtained from this cost-effective geotechnical investigation method.
Abstract
As part of the global efforts to mitigate climate change and foster sustainable development, the construction of solar power plants has experienced significant growth in the [...]
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Vibro-Penetration Tests for The Evaluation of Blasting Compaction in very loose Sandy dumps
R. Cudmani*, R. Cudmani

ISC2024.

Abstract
During the so‐called vibro‐penetration test (VPT), a vertical harmonic excitation force drives a rod with a conical tip into the ground. For the evaluation of the VPT resistance, an energy‐corrected number of vibration cycles Nz10 for 0.10 m penetration is used. In order to determine Nz10, the dynamic penetration resistance, the tip and shaft resistance, the tip acceleration, and the depth of the penetrometer tip are continuously recorded and processed according to a mechanical vibro-penetration model. Calibration chamber tests, field tests, and Finite Element Analyses, which were carried out to validate the assumed penetration mechanism and to investigate the influence of the state variables (density and effective stresses) and the machine parameters (static moment, frequency, and static load) on the penetration resistance. As the force and displacement of the penetrometer are determined at the tip, an equivalent spring stiffness, which is correlated with the soil stiffness, can be calculated over the driving depth. Since vibro‐penetration resistance is closely related to the soil behavior under cyclic shearing, the VPT should be more appropriate than monotonic tests to characterize the ground response to repeated dynamic and alternating loading, e.g. pile drivability, ground compaction, and soil liquefaction susceptibility. Compared with the cone-penetration test (CPT), the VPT equipment is much lighter, the execution time is shorter, and in‐situ investigations of medium-dense to dense cohesionless soils at large depths are feasible. In this contribution, VPT and CPT are used to investigate the effect of blasting compaction in very loose dumps from opencast mines in Lusatia, Brandenburg, Germany. It is concluded that the VPT results are reproducible. In addition, Nz10 shows a clear correlation with the state variables and the VPT records before and after blasting compares well with the results of CPT.
Abstract
During the so‐called vibro‐penetration test (VPT), a vertical harmonic excitation force drives a rod with a conical tip into the ground. For the evaluation of the VPT [...]
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Dynamic modulus E_kd evaluation by dynamic penetration test
S. Lopez, M. Benz*, S. Espinoza, J. Canou, J. Dupla

ISC2024.

Abstract
Dynamic penetration tests DPT have been routinely employed in the geotechnical characterization of the subsoil in different types of engineering projects. The evaluation of the results of these tests has been performed considering a limited number of parameters obtained in the field, so the definition of new parameters allows a more accurate evaluation of soil characteristics. The purpose of this paper is to present a methodology for the evaluation of the dynamic modulus (Ekd) based on the analysis of the dynamic force and velocity signals recorded in each hammer impact. Variable energy DPT tests were performed on Fontainebleau NE34 sand specimens in a K0 calibration chamber. For each hammer impact on the penetrometer, a decoupling and wave reconstruction method was applied to obtain the force and velocity signals at the cone-soil interface, which are analyzed in the frequency spectrum to obtain the Ekd modulus. The results show that it is possible to evaluate the dynamic modulus at different vertical loading conditions and independent of the impact energy level of the hammer on the penetrometer.
Abstract
Dynamic penetration tests DPT have been routinely employed in the geotechnical characterization of the subsoil in different types of engineering projects. The evaluation of [...]
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Evaluation of Cone Resistance Results from Dutch Formula
C. Forestti, C. Oliveira, M. Benz, P. Breul, B. Chevalier

ISC2024.

Abstract
The Dynamic Penetration Test (DPT) is widely applied for soil field characterization. The technique is usually appreciated as a simple and cost-effective means of determine soil resistance which can be obtained either from Newtonian or from wave equation methods. While wave equation analysis has demonstrated numerous advantages in recent decades, its adoption is constrained by the need for specific instrumentation and more complex analysis. Consequently, the simpler Newtonian analysis, and particularly the Dutch Formula specified by ISO 22476-2, remains the more commonly used approach for routine geotechnical applications. To ensure its accuracy comparing to wave equation-based methods, a field campaigns were conducted on experimental sites with various soil types. The campaigns included Cone Penetration Test (CPT), which is used as a reference tool in this study, and instrumented DPTs allowing easy application of wave equation methods. Results revealed that Dutch Formula resistance values were comparable to both CPT results and those derived from wave equation methods in most cases. In addition, DF variation formula applying energy measurement seemed to underestimate cone resistance in all case examined. The study highlights the importance of applying good practice rules to enhance DPT results
Abstract
The Dynamic Penetration Test (DPT) is widely applied for soil field characterization. The technique is usually appreciated as a simple and cost-effective means of determine [...]
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Investigation and monitoring to model the interaction between the Scrovegni’s Chapel in Padova (Italy) and the underlying foundation soil
G. Dalla Santa, P. Simonini*

ISC2024.

Abstract
In Padova's historic centre lies the renowned Scrovegni’s Chapel, painted by Giotto in 1303. The local subsoil primarily consists of silty sand with some layers of silt. The crypt beneath acts as a buffer against soil moisture, preventing damage to the frescoes. However, during heavy rain, groundwater rises flowing across the floor and lateral walls, therefore flooding the pavement. A pumping system is eventually activated to mitigate the pavement inundation. Several investigations including geophysical surveys, piezocone tests, and boreholes with soil sampling have been conducted to provide the subsoil geotechnical model and understand the local hydrogeological behaviour. Monitoring systems, such as piezometers, deep extensometers and optical fiber cables, track groundwater levels and long-term soil displacements. The paper aims to characterize the subsoil's stratigraphy, mechanical properties and permeabilities to model how the environmental conditions affect the ancient Chapel and ensure its long-term stability.
Abstract
In Padova's historic centre lies the renowned Scrovegni’s Chapel, painted by Giotto in 1303. The local subsoil primarily consists of silty sand with some layers of silt. [...]
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In-situ experimental tests for shallow foundation design using dynamic penetration testing method
T. Luong*, P. Reiffsteck, M. Benz Navarrete, F. Szymkiewicz

ISC2024.

Abstract
To develop an advanced and innovative method for shallow foundations design with the aid of dynamic penetration testing technique, several in-situ tests are realized on various experimental sites to enrich the available database and to valid the computed results. This communication presents the field tests consisting of the Foundation Loading Tests and the Dynamic Cone Penetration Tests (DCPT): their performance, operation principles, equipment and results obtained. A direct method for bearing capacity prediction based on the measured data is also proposed, then compared to other approaches already standardized. Therefore, this study contributes to the improvement of the shallow foundations design method by providing full-scale experimental results and discussing their findings.
Abstract
To develop an advanced and innovative method for shallow foundations design with the aid of dynamic penetration testing technique, several in-situ tests are realized on various [...]
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Responses of Dynamic Penetrometers according to Hammer Weight and Drop Height
J. Lee*, G. Park, N. Kim, D. Kim, S. Kim

ISC2024.

Abstract
This study characterizes the dynamic responses of hammer weight and drop height in dynamic penetration tests. The tests were conducted using an instrumented dynamic cone penetrometer (IDCP) to obtain the dynamic responses during penetration. Various hammer weight and drop height types were used at a fixed potential energy of 45.1 N∙m. The measured compression stresses and transferred energies into the rod head and cone tip were analyzed for hammer weight and drop height. The compression stress at the rod head varied with the hammer weight and drop height, whereas the compression stress at the cone tip is irrelevant to the hammer weight or drop height. In addition, the transferred energies into the rod head and cone tip increased as the hammer weight increased but decreased as the drop height increased. This study demonstrates that hammer weight and drop height should be considered when the characteristic of subsurface is profiled using dynamic penetrometer.
Abstract
This study characterizes the dynamic responses of hammer weight and drop height in dynamic penetration tests. The tests were conducted using an instrumented dynamic cone penetrometer [...]
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Applicability of CPTU to characterize diatomaceous fine-grained soils: a case study in Euganean Hills (Italy)
G. Dalla Santa*, F. Ceccato, P. Simonini

ISC2024.

Abstract
Diatomaceous soils, composed of diatom fossils and clay minerals typically formed in volcanic environments, exhibit characteristics such as low unit weight, high plasticity and liquid limit, significant compressibility, and high friction angles. Despite their presence in various locations globally, knowledge about their geotechnical behavior is limited and primarily based on laboratory tests conducted on artificial samples. This paper presents data obtained from undisturbed samples of natural diatomaceous soils and discusses the interpretation of Cone Penetration Test with Pore Pressure (CPTU) data to classify these complex non-textbook soils and estimate their mechanical properties. The study area is situated in the Po Plain near the thermal anomaly region of the Euganean Hills in Northeast Italy. Three CPTUs and one borehole with the collection of four Osterberg undisturbed samples were conducted. Laboratory tests on the undisturbed samples provided values for Atterberg Limits, soil unit weight, in-situ void ratio, compressibility, and permeability, which were compared with estimations derived from CPTU data analysis. Moreover, Scanning Electron Microscope images provided insight into the distinctive microstructure of diatom microfossils embedded in a clayey matrix. Based on these comparisons, CPTU proves to be effective in estimating relevant parameters of diatomaceous soils, particularly the Soil Behavior Type (SBT) and consolidation coefficient from dissipation tests. However, the agreement in estimating the oedometric modulus is less satisfactory. Therefore, for a precise definition of the geotechnical model, it is recommended to conduct additional laboratory tests, particularly those focused on defining compressibility parameters, given the unique behavior of natural diatomaceous soils.
Abstract
Diatomaceous soils, composed of diatom fossils and clay minerals typically formed in volcanic environments, exhibit characteristics such as low unit weight, high plasticity [...]
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Soil Characterisation Using a Dynamic Penetrometer
J. Rong*, M. Nazem

ISC2024.

Abstract
In offshore engineering, a geotechnical site investigation is an important step in analysis and design to ensure the integrity and serviceability of infrastructure. The Cone Penetration Test (CPT) stands as the prevailing technology for offshore soil characterisation. However, this test method requires a substantial allocation of resources for equipment transportation and operation personnel. This proves inefficient and costly for conducting comprehensive surveys over ocean beds. Alternatively, free-falling penetrometers (FFP) have attracted attention as a CPT replacement for soil characterisation. Nevertheless, these devices can penetrate only to shallow depths within soils, limiting their applicability for offshore site investigation purposes. A new device has been created to overcome this constraint, featuring a dynamic penetrometer launched by a speargun. Unlike conventional free-falling penetrometers, this apparatus can attain a greater penetration ratio, exceeding 20 times its diameter. The process of experimental testing yielded notable enhancements, particularly in effectively addressing challenges associated with tilting when attempting low-penetration depths. By implementing rate corrections into the methodology, promising results were obtained for equivalent static penetration resistance. This approach not only represents the capacity to influence future penetrometer designs but elevates the overall efficiency of in-situ soil characterisation procedures.
Abstract
In offshore engineering, a geotechnical site investigation is an important step in analysis and design to ensure the integrity and serviceability of infrastructure. The Cone [...]
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Machine Learning-Based Modeling of Net Ecosystem Exchange Using Numerical Weather Data and Satellite Images
N. Kim*, J. Cho, Y. Lee

ISC2024.

Abstract
Recently, the increasing severity of climate change attributable to global warming has emphasized the imperative of carbon absorption to mitigate greenhouse gas emissions. The use of the carbon sink based on the carbon absorption and storage functions of forests is suggested as an effective alternative for domestic greenhouse gas reduction. Additionally, agricultural land cover comprises approximately 38% of the Earth's surface, underscoring the importance of comprehensively understanding the carbon cycle within not only forests but also agricultural landscapes. This significance arises from the fact that agricultural land locally amplifies seasonal variations in carbon dioxide by approximately 25% compared to vegetated areas. Consequently, a comprehensive understanding of both forest and agricultural land carbon cycles is imperative, necessitating quantitative analysis of carbon uptake in agricultural settings. Thus, this study aims to construct a machine learning-based model for estimating the net ecosystem exchange (NEE) of rice paddies in South Korea using ground flux data, meteorological variables, and satellite images. Through quantitative assessment, the NEE was determined, with a mean absolute error of 1.387, root mean square error of 2.203, and correlation coefficient of 0.872. Notably, observed NEE values demonstrating extremes in magnitude were associated with calculation errors, reflecting tendencies of both underestimation and overestimation. This phenomenon is likely attributed to the study's reliance on a limited dataset and the inherent challenges of training models across a broad spectrum of observations. To enhance calculation accuracy, future endeavors should focus on accumulating a more extensive repository of NEE flux observations and leveraging high-resolution satellite imagery and meteorological datasets for refining machine learningbased models.
Abstract
Recently, the increasing severity of climate change attributable to global warming has emphasized the imperative of carbon absorption to mitigate greenhouse gas emissions. [...]
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AI Modeling for Characterization of Paddy Rice Yields under Extreme Weather Conditions Using Remote Sensing and Geospatial Data
J. Ahn*, Y. Lee

ISC2024.

Abstract
Climate change, such as increase in CO2 levels and rising temperatures, can have a significant impact on paddy rice production and increase the uncertainty of yield forecasts. This study aims to employ AI modeling for forecasting paddy rice yield and present the findings of a quantitative analysis to determine its ability to generate stable forecasts under extreme weather conditions, such as heatwaves, low temperatures, and heavy rainfall. Vegetation growth indices from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite product were utilized. These indices include the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Leaf Area Index (LAI), Fraction of Absorbed Photosynthetically Active Radiation (FPAR), and Near-Infrared Reflectance of vegetation (NIRv). Meteorological variables such as downward solar radiation flux, daily temperature difference, precipitation, relative humidity, and temperature were also used. Over 23 years of experimentation (2000-2022), yields under extreme weather conditions did not exhibit a significant difference from the normal period, with a Mean Absolute Error (MAE) ranging from 0.30 to 0.33 ton/ha, representing a 4-5% error of the average yield. This study presents an AI modeling methodology that enables stable predictions of paddy rice yields, even under extreme weather conditions. Future work should focus on refining input data and optimizing the model by analyzing cases of extreme weather.
Abstract
Climate change, such as increase in CO2 levels and rising temperatures, can have a significant impact on paddy rice production and increase the uncertainty of yield forecasts. [...]
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Taillings Characterization: Exploring Laser Granulometry with Machine Learning
I. Bernardes, G. Frainz*

ISC2024.

Abstract
The conventional particle size test has been a widely used method in the characterization of soils and tailings. Such information is particularly useful in the evaluation of materials deposited in tailing stacks or compacted landfills, which must follow reference particle size ranges. However, the method has limitations, the main one being the execution time, which usually lasts around three days. On the other hand, laser testing appears as a viable alternative. This innovative method obtains the grain size curve of the soil through the light dispersion pattern and lasts a few minutes, a significant improvement over the conventional method. Furthermore, this method can cover particle size ranges of up to 0.1 micrometers, while the conventional method is limited to 1 micrometer. Despite the benefits of using this equipment, the laser grain size test does not yet have specific standardization for use in the field of soil mechanics. In this context, this work proposes the use of machine learning techniques to demonstrate the existence of compatibility between both methods. To this end, tests were carried out using both methodologies on different samples of iron ore tailings and an algorithm was developed to predict the material classification. The evaluation of the results made it possible to verify the consistency and precision of the results between the two methods, reinforcing the reliability and viability of the laser test as an efficient alternative to the traditional method
Abstract
The conventional particle size test has been a widely used method in the characterization of soils and tailings. Such information is particularly useful in the evaluation [...]
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Integrated geophysical methods in identifying preferential flow paths in an earth dam
L. Rezende, C. Aguiar*, L. Soares, C. Lemos, L. Dias

ISC2024.

Abstract
The evaluation of safety conditions in dams is of utmost importance to ensure stability and often involves subsurface investigation methods. Geophysical methods have emerged as a modern and relevant alternative, often more practical than traditional direct methods. This study aims to integrate the application and interpretation of resistivity and selfpotential methods to identify preferential flow paths in a small earth dam. The investigation was conducted at a dam located on the Viçosa Campus of the Federal University of Viçosa (UFV), with three main soil layers: embankment, silty clay, and alluvium. Analysis of the results revealed potential conductive zones and negative spontaneous potential anomalies, suggesting the occurrence of piping and the presence of buried structures in the spillway area. Moreover, the geophysical investigation methodology proved effective in evaluating geotechnical characteristics and flow conditions of the dam, contributing to the foundation for future safety and stability analyses of the structure.
Abstract
The evaluation of safety conditions in dams is of utmost importance to ensure stability and often involves subsurface investigation methods. Geophysical methods have emerged [...]
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Data-driven Multi-stage Sampling Strategy for Machine Learning of Underground Digital Twins Consdiering Stratigraphic Uncertainty
C. Shi*, Y. Wang, V. Kamchoom

ISC2024.

Abstract
A sound understanding of subsurface geological conditions is crucial for the digitalisation of underground infrastructure. The building and updating of underground digital twins heavily rely on sparse geotechnical measurements (e.g., boreholes) retrieved from the ground, and an efficient sampling strategy can facilitate the interpretation of subsurface heterogeneities. Geotechnical sampling design can be viewed as a constrained optimization process that aims to obtain as much geological information as possible from a limited number of sampling locations within a given site boundary. In this study, a data-driven intelligent sampling strategy is proposed to optimize borehole locations for a multi-stage site investigation of a three-dimensional (3D) geological domain. The initial sampling plan is determined using weighted centroidal Voronoi tessellation, which assigns uniform sampling densities to zones of different importance. Measurements obtained from the initial stage are combined with prior geological knowledge to build underground digital twins using an image-based stochastic modelling method. Multiple realizations of the geological domain can be developed under the framework of Monte Carlo simulation, and stratigraphic uncertainties associated with multiple random realizations can be quantified using information entropy. The location with the maximum entropy is adaptively selected as the next optimal sampling location. The proposed method is the first sampling strategy that can explicitly consider 3D subsurface stratigraphic variations. The performance of the proposed multi-stage sampling strategy is demonstrated using a simulation example. Results indicate that the proposed method can efficiently identify the optimal sampling locations while accounting for irregular site geometries and 3D subsurface stratigraphic uncertainties.
Abstract
A sound understanding of subsurface geological conditions is crucial for the digitalisation of underground infrastructure. The building and updating of underground digital [...]
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Predicting Soil Behavior Types Along the Danube: An AI-Driven Approach Using CPT Data in the Szigetköz Floodplain Area
E. Koch*, S. Alsamia

ISC2024.

Abstract
The Szigetköz (Hungary) is a hotbed of sand boil formation, owing to the combination of a 100-250 m thick gravel layer beneath a relatively thin covering of poor soil with varying thickness. Soil behavior is critical for flood protection in this region. This work proposes a novel way to predict Soil Behaviour Types (SBT) based on detailed CPT data collected from 29 sites in the Szigetköz area using an artificial intelligence (AI) model. The study follows a methodically planned approach that includes data collecting, preprocessing, SBT categorization based on the SBT chart developed by Robertson et al. (1986), and AI model building. The CPT dataset contains critical metrics like cone resistance and friction ratio, which are essential in characterising soil behavior. The AI model, built with powerful machine learning algorithms, is intended to learn complicated associations within data to forecast SBT classifications. Extensive feature selection, hyperparameter tuning, and cross-validation are all necessary steps in model construction to ensure accuracy and generalizability. The results show that the model can accurately forecast SBT classifications for the Szigetköz area, shedding information on the soil's behavior near the Danube River. Spatial distribution visualizations emphasize the region's many SBT categories, giving valuable information for engineering projects, land use planning, and environmental conservation activities. The AI model's interpretability elucidates the major CPT parameters driving SBT forecasts, providing stakeholders with actionable information for decision-making. Furthermore, validation of the model with new, previously unseen CPT data confirms its applicability and robustness in real-world circumstances.
Abstract
The Szigetköz (Hungary) is a hotbed of sand boil formation, owing to the combination of a 100-250 m thick gravel layer beneath a relatively thin covering of poor soil with [...]
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Artificial Intelligence in Dynamic Compaction for Geotechnical Site Characterization
J. Park*, C. Lee

ISC2024.

Abstract
We present a novel method using four artificial intelligence (AI) algorithms to anticipate the cumulative degree of soil compaction (CDSC) after dynamic compaction (DC). Four AI algorithms adopted in this study include support vector regression SVR, artificial neural network (ANN), random forest (RF), and gradient boosting machine (GBM). Input variables for AI algorithms involve the average SPT N-value before dynamic compaction, cumulative applied energy normalized with a cross-sectional area of tamper, and the number of the tamper drops. Apart from cross-validation with a testing set, additional in situ test data compiled from a different section within the studied site are used to estimate the generalized capacity of the AI models. In addition, we conduct out-of-distribution analyses for the four AI algorithms in view of parametric studies. The CDSC prediction performance for the four AI models results in high prediction metrics of accuracy with the r2 higher than 0.9 for the testing scenario while the r2 of the other AI models is more than 0.9 when out-of-sample data are considered except for the GBM. The ANN seems to be the best model as the parametric study considers out-of-distribution data and suggests a strong relationship between input variables and CDSC that is more coherent with engineering principles for DC. Finally, the ANN model can be utilized to develop a mathematical model for CDSC prediction.
Abstract
We present a novel method using four artificial intelligence (AI) algorithms to anticipate the cumulative degree of soil compaction (CDSC) after dynamic compaction (DC). Four [...]
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Integrating laboratory and geophysical data considering measurement errors
J. Xie, J. Huang*, S. Huang

ISC2024.

Abstract
Laboratory and geophysical tests are commonly used in site characterization. Combining these data sets based on empirical relationships can essentially enhance data interpretation. While in traditional approaches, the uncertainties in the relationship between these data sets are ignored. The Bayesian updating method is used to consider these uncertainties. Besides, the uncertainties due to measurement errors in the laboratory tests, particularly for preconsolidation pressure, are considered based on the kriging fitting method. The outcomes of kriging fitting are utilized to establish the prior distribution, and these outcomes are then compared against the baseline established by the trend fitting method. The Markov chain Monte Carlo (MCMC) algorithm is applied to incorporate the shear wave velocity measurements from a seismic dilatometer test to derive the posterior distribution. Bayesian updating of parameters considering measurement errors is able to get a more convincing design profile.
Abstract
Laboratory and geophysical tests are commonly used in site characterization. Combining these data sets based on empirical relationships can essentially enhance data interpretation. [...]
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Application of handheld mobile terrestrial laser scanning for cultural heritage documentation.
A. Llabani*, N. Kopliku

ISC2024.

Abstract
The preservation and documentation of cultural heritage sites are fundamental to safeguarding our shared history and identity. This study explores the innovative application of the viDoc RTK rover for cultural heritage documentation, presenting a forward-looking approach to capturing high-precision spatial data in the preservation and analysis of Brari bridge located in Tirana, Albania. Handheld mobile terrestrial laser scanning (HMTLS) offers versatility and mobility, enabling rapid and non-invasive data acquisition in complex and challenging environments. The methodology encompasses equipment selection, data acquisition techniques, and data processing workflows tailored for HMTLS technology. The results demonstrate the potential of HMTLS to produce highly accurate 3D models, showcasing intricate architectural details and capturing fine surface textures with an accuracy of 3 cm. Furthermore, the portability of handheld devices allows for documentation in areas where traditional scanning methods may be impractical. This study underscores the transformative impact of HMTLS on cultural heritage preservation, offering a cost-effective, efficient, and accessible means of creating digital archives. The adoption of this technology contributes to the long-term conservation, research, and education associated with our cultural heritage, ensuring that these invaluable assets continue to inspire and inform future generations.
Abstract
The preservation and documentation of cultural heritage sites are fundamental to safeguarding our shared history and identity. This study explores the innovative application [...]
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A combined approach to Automated Parameter Determination (APD)
I. Marzouk*, F. Tschuchnigg

ISC2024.

Abstract
The success of numerical analysis relies on several factors, with one crucial aspect being the accurate determination of constitutive model parameters. Extracting these parameters directly from in-situ tests has several advantages, such as costeffectiveness and minimal soil disturbance. However, obtaining soil parameters directly from in-situ tests is not feasible, as empirical correlations are used to interpret them. An ongoing research project aims to create an automated parameter determination (APD) framework using a graph-based approach to determine constitutive model parameters from in-situ tests. The process involves using two spreadsheets as input: the first defines the parameters, while the second specifies the correlations used to compute them. The system then generates connections between the parameters and computes values for each one. The paper discusses the validation of the correlations database used by the system, which includes over 100 correlations for deriving parameters for various soil types. The framework determines parameters based on cone penetration tests (CPT), dilatometer tests (DMT), and in-situ shear wave velocity measurements. The system's output is compared to values interpreted from laboratory tests. To collect data for this validation, a web-based application "Datamap" was employed, which stores and categorizes geotechnical data. The validation process utilized data from the Norwegian GeoTest Sites (NGTS), specifically the NGTS-silt project. The parameters were calculated based on CPT, DMT, and in-situ shear wave velocity measurements. Ongoing research aims to evaluate the accuracy of the derived parameters and expand the system's capabilities to include additional in-situ tests
Abstract
The success of numerical analysis relies on several factors, with one crucial aspect being the accurate determination of constitutive model parameters. Extracting these parameters [...]
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The stratigraphic reconstruction of longitudinal tunnel based on improved coupled Markov chains
Q. Jiang*, J. Zhang, D. Zhang

ISC2024.

Abstract
The distribution of natural strata is uncertain due to tectonic movements and sedimentation. Capturing geological uncertainty is a challenge for traditional deterministic models. In this study, an improved three-dimensional coupled Markov chains method for probabilistic stratigraphic reconstruction was developed. This method considers the correlation between the field borehole data. On this basis, an inversion analysis method for horizontal transition probability matrix estimation is proposed. This method makes the predictions more suitable for possible stratigraphic distributions. The accuracy of the method was further verified by different borehole schemes from the Mawan Tunnel in Shenzhen. The results show that the proposed method can still have high accuracy when the number of boreholes is sparse. This method can reflect the asymmetry, continuity and anisotropy of three-dimensional strata.
Abstract
The distribution of natural strata is uncertain due to tectonic movements and sedimentation. Capturing geological uncertainty is a challenge for traditional deterministic [...]
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Digitization of subsurface geological stratigraphy using machine learning and neighborhood aggregation
Y. Hu*, Z. Wang, X. Guo

ISC2024.

Abstract
In engineering geology and geotechnical engineering, subsurface soils and rocks are natural geomaterials and exhibit inherent variability in stratigraphy due to geological deposition process. Explicit knowledge of subsurface stratigraphy is a critical input for the analysis, design, and construction of geotechnical engineering systems. However, the accurate and reliable modelling of subsurface geological stratigraphy is challenging due to the limited number of available boreholes in practice and the complex nature of soil stratigraphy. This paper presents an innovative machine learning framework built upon the neighborhood aggregation technique for the prediction of digitized subsurface geological stratigraphy. To predict the stratigraphy at a given point of interest, neighborhood aggregation is first performed to intelligently consolidate the stratigraphy information from its neighboring boreholes, resulting in additional features associated with the target location. By combining the extra stratigraphy information with conventional location-specific features, the framework enhances the predictive capabilities of classical machine learning models at a finer scale. The proposed framework is implemented using common machine learning models and is validated using a simulated benchmark 3D example. The results of leave-one-out cross-validation demonstrate that the proposed framework can improve the performance of classical machine learning models, leading to more reasonable stratigraphy transition and associated uncertainty quantification.
Abstract
In engineering geology and geotechnical engineering, subsurface soils and rocks are natural geomaterials and exhibit inherent variability in stratigraphy due to geological [...]
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Calibration and Test Bed Simulation of a 40 Cm2 Cptu Cone
E. Baziw*

ISC2024.

Abstract
In cone penetration testing (CPT) an electronic penetrometer is pushed at a constant rate into penetrable soils and cone bearing (qc), sleeve friction (fc) and dynamic pore pressure (u) are recorded with depth. The measured qc, fs and u values are utilized to estimate soil type and associated properties. Cone tips have areas which vary from 5cm2 to 40 cm2. The larger tips allow for the penetration of gravely soils while small cone tips are utilized for shallow soil investigations. The measured cone bearing and sleeve friction values are blurred or averaged. The measurements are also susceptible to anomalous peaks and troughs due to the relatively small diameter cone tip penetrating sandy, silty and gravelly soils. The cones with relatively smaller cone tips are significantly more susceptible to the anomalous peaks and troughs while the cones with larger cone tips are more susceptible to the smoothing of the cone tip and sleeve friction measurements. Baziw Consulting Engineers (BCE) has invested considerable resources in addressing the qc and fs measurements distortions. This paper outlines the techniques developed by BCE and integrates them so that optimal soil properties can be obtained from CPT data sets. Particular focus is put on relatively larger cone tips because they can penetrate soils with high resistance and are less susceptible to the additive measurement noise of anomalous peaks and troughs. The anomalous peaks and troughs are more challenging to remove or minimize than the qc and fs blurring effects. It is of paramount importance to first implement newly developed signal processing and optimal estimation algorithms on extensive test bed simulations prior to processing real data sets. This paper also outlines the results from processing a challenging test bed simulation of a 40 cm2 cone tip data set with BCE’s newly developed algorithms.
Abstract
In cone penetration testing (CPT) an electronic penetrometer is pushed at a constant rate into penetrable soils and cone bearing (qc), sleeve friction (fc) and dynamic pore [...]
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Cone Penetration Test-Based Correlations to Forecast Critical State Parameters
J. Gamez*, S. Olson

ISC2024.

Abstract
In critical state soil mechanics, the critical state refers to the combination of effective stress and void ratio (e) at which a soil continues to shear with no change in effective stress, shear stress, and e. The phenomena can be visualized using the critical state line (CSL). The CSL represents the locus of e at critical state with effective mean stress (σ′mean). To define the CSL, the CSL slope (λ), termed “compressibility,” and CSL y-axis intercept at 1 kPa (Γ), termed “altitude,” are required. The CSL in e – σ′mean space provides a simple model of complex soil behavior that allows engineers to construct constitutive models using the state parameter (ψ), which is the mathematical difference between the in-situ e of the soil and the e of the soil at critical state. Currently, Γ can be obtained only through laboratory testing, while λ and ψ can be obtained via laboratory testing or correlation. This paper presents forthcoming correlations based on the ΔQ soil behavior index (which is obtained via the cone penetration test, CPT) to forecast Γ, λ, and ψ, and compares the ΔQ-based correlations’ performance to other CPT-based correlations as well as to data obtained from literature. To compare the correlations, the authors used data from a site investigation performed in Fraser River sand as part of the Canadian Liquefaction Experiment.
Abstract
In critical state soil mechanics, the critical state refers to the combination of effective stress and void ratio (e) at which a soil continues to shear with no change in [...]
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Inferring Spatial Variation of Soil Classification Using Clustered Bayesian Analysis by Both CPT and Borehole Data
H. Kamyab Farahbakhsh*

ISC2024.

Abstract
Soil boundary delineation is an important task in geotechnical site characterization. It can be achieved by either extracting borehole samples, conducting laboratory tests, and classifying them according to a soil classification system such as the Unified Soil Classification System (USCS) or utilizing multiple cone penetration test (CPT) soundings, and identifying soil boundaries at the soundings from the Ic (soil behavior type index) profiles. However, most soil-layer delineation methods can only take a single type of test result as the input. For instance, the well-known Markov random field (MRF) method can only take soil-type data such as sand, silt, or clay at boreholes as the input. Recognizing that soil classifications and soil properties are correlated, this paper proposes a novel coupled MRF-Bayesian framework to infer the spatial variation of USCS classifications (e.g., sand, silt, and clay) as well as soil properties by integrating both CPT and borehole data. This integrated approach leverages both CPT and borehole data to address some main challenges e.g., uncertainties and multivariate soil data input in underground stratification problems by simultaneous sampling of soil properties and soil types. The new unified framework can accommodate multivariate data, hence the new framework is compatible with the geotechnical engineering practice. The uncertainties for the spatial variation of USCS classification at sounding locations are quantified through a “layer-specific” Bayesian updating i.e., updating posterior cross-correlation behaviors for different layers (such as sand, silt, and clay), independently. In this Bayesian updating, soil-type data can provide some information about the soil properties according to the unified soil classification system. Further, the soil boundaries can be identified across the entire domain by the realization of conditional random fields of soil properties once the spatial variation of USCS classification is inferred at sounding locations, followed by a 3-dimensional Markov random field process.
Abstract
Soil boundary delineation is an important task in geotechnical site characterization. It can be achieved by either extracting borehole samples, conducting laboratory tests, [...]
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Data-Driven Two-Dimensional Near-Surface Seismic Imaging
J. Vantassel*, S. Bhochhibhoya

ISC2024.

Abstract
Non-invasive site characterization techniques have the potential to rapidly evaluate large subsurface volumes to guide subsequent invasive geotechnical site investigation. Among these methods, seismic full waveform inversion (FWI) stands out for its potential to recover detailed two-dimensional (2D) images of the subsurface. However, FWI’s need for substantial computational resources and sensitivity to the initial starting model has limited its utilization as a generalpurpose geotechnical site characterization tool. Addressing this, prior studies have shown data-driven methods can predict 2D subsurface structures composed of soil over rock. In the present study, we aim to generalize these findings to all nearsurface conditions. We propose a novel model generation framework that utilizes techniques from geostatistics to generate complex 2D subsurface models. The generated models include dipping soil and rock layers, soil lenses, boulders, and underground utilities; none of which have been considered previously. We use our model generation framework to simulate 100,000 2D subsurface models. We simulate field data acquisition along these 100,000 synthetic models, by numerically solving the elastic wave equation using an impulse source at the model’s center surrounded by 24 receivers (12 on either side). The data-driven predictive model, trained on 90% of the simulated data, achieved a mean absolute percent error on the testing set of 19%. Furthermore, these predictions are made within fractions of a second circumventing the computational and starting-model-related challenges associated with traditional 2D FWI. These results demonstrate that data-driven methods can predict complex images of the subsurface to enable rapid subsurface imaging for geotechnical applications.
Abstract
Non-invasive site characterization techniques have the potential to rapidly evaluate large subsurface volumes to guide subsequent invasive geotechnical site investigation. [...]
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Geological and geotechnical study of a construction site in Porto Romano area-Albania
A. Malaj*, S. Allkja, J. Belliu, I. Kero

ISC2024.

Abstract
Porto Romano port complex new facilities are part of the expansion plans of Durres port and its modernisation. However, the relocation site presented many significant spatial and geotechnical challenges to be considered and mitigated. Soil conditions and the country’s high seismic activity meant the project required extensive feasibility and technical studies to find a safe and sustainable approach. For a detailed geological and geotechnical investigation of the area, various geotechnical, geophysical tests were carried out such as: borings, SPT test, CPTU test, Seismic refraction, MASW, Downhole and HVSR allowing to obtain the fundamental resonance frequency of the ground. Field recordings per each layer were than compared and calibrated to the results and tests performed in the laboratory. The construction site displayed a variety of soils from soft to firm silty Clays, to loose to medium dense silty Sands and layers with high organic content. During execution of SPT tests, sandy layers gave more satisfactory results, meanwhile, for silty CLAY layers, the results of CPTU testing were considered in analysis. This detailed soil investigation and characterization served to properly design the new port facilities, identify, and protect from the liquefaction phenomena at this specific site.
Abstract
Porto Romano port complex new facilities are part of the expansion plans of Durres port and its modernisation. However, the relocation site presented many significant spatial [...]
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