Documents published in Scipedia

• Hydraulic Profiling Tool for Groundwater Vulnerability Assessment at an MSW Landfill

  P. Singh*, D. Haritwal, G. Ramana, M. Datta

  ISC2024.

  
  

  Abstract

  Characterization of the unsaturated zone below an MSW landfill is critical to evaluate the groundwater pollution vulnerability assessment. The permeability of the soil in the unsaturated zone, the depth of the water table, and the quality of pore water in the soil can provide a reliable site-specific estimate of pollution vulnerability. To evaluate these factors, an attempt was made to use the hydraulic profiling tool (HPT) in the unsaturated zone below a non-engineered MSW landfill in Delhi. HPT was equipped with an injection logger capable of qualitatively measuring permeability at the cm scale and an electrical conductivity (EC) dipole that measures the bulk soil conductivity. HPT findings were compared with piezocone penetration tests (CPTu) and the electrical conductivity of extracted pore water from the soil cores. The results indicate that pressure from the injection logger works effectively for medium/fine sand and silt and has greater sensitivity to permeability changes for these soils than CPTu. Pore-water EC was found to have a good correlation with volumetric water content and EC from HPT. A groundwater vulnerability matrix was conceptualized using factors based on the time of leachate travel and maximum pore-water EC observed, both derived from HPT, and risk scores were assigned from 1-5, corresponding to the 9 zones of the matrix. The locations surveyed at the dumpsite received scores of 4 and 5, which depicts high vulnerability. The results indicate that HPT can be used for rapid site-specific groundwater vulnerability assessments.

  Abstract
  Characterization of the unsaturated zone below an MSW landfill is critical to evaluate the groundwater pollution vulnerability assessment. The permeability of the soil in [...]

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• Comparison Between Eggshell Lime and Commercial Lime as a Soil Stabilizing Agent

  B. Meneguz, H. Nierwinski, B. Caetani*

  ISC2024.

  
  

  Abstract

  Reducing the extraction of natural resources is a current demand in the construction industry. Studies show that eggshells are rich in calcium carbonate and have the potential to replace limestone in lime production. In this context, the objective of this article is to use an eggshell lime produced in the laboratory to stabilize a residual clayey soil and compare the unconfined strength of the admixtures with others using commercial dolomitic lime. Different lime contents and porosities were evaluated and the porosity/lime ratio was studied to understand the unconfined strength behavior of admixtures. In addition to the soil and limes characterization tests, X-ray diffraction tests were carried out to analyze the chemical and mineralogical composition of the materials. The results showed that increasing lime content and decreasing porosity increased unconfined strength. Also, the unconfined strength achieved with the eggshell lime was greater than that achieved with dolomitic lime for the same lime content. The X-ray diffraction tests showed that the eggshell lime is composed almost entirely of calcium hydroxide, and microscopic images demonstrated much stronger bonds in the final product obtained from eggshell lime. The porosity/lime ratio was a good parameter for evaluating unconfined strength. A unique relationship was achieved linking unconfined compressive strength with the porosity/lime ratio for both the eggshell and the dolomitic lime mixtures.

  Abstract
  Reducing the extraction of natural resources is a current demand in the construction industry. Studies show that eggshells are rich in calcium carbonate and have the potential [...]

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• Considerations on the site characterization of tropical soils by in situ tests

  B. Rocha, R. Rodrigues, H. Giacheti*

  ISC2024.

  
  

  Abstract

  The fundamentals for predicting the mechanical behavior of soils by in situ tests have been developed for conventional soils (either clay or sand) based on the stress history. The behavior of unusual geomaterials, such as the tropical soils, is characterized by bonding and structure, anisotropy as well as by the unsaturated condition. The behavior of tropical soils cannot be correctly predicted by models and correlations developed by the Classical Soil Mechanics. This paper presents the fundamentals of the behavioral classifications used to interpret CPT and SDMT and discusses their applicability to tropical soils, especially those of pedogenetic evolution of sandstone. Laboratory and in situ tests (CPTu and SDMT) were carried out at two research sites in São Paulo state, Brazil, at different periods of the year to better understand the soil behavior and the seasonal effects. Classifications and correlations to estimate soil parameters from CPTu and SDMT are assessed. Interrelationships between elastic parameters of small (G0) and large to medium strain parameters (qc, ED, MDMT) determined by in situ tests are presented to identify the presence of microstructure and unusual soil behavior. Classification criteria based on these relationships to identify collapsible soils also is presented

  Abstract
  The fundamentals for predicting the mechanical behavior of soils by in situ tests have been developed for conventional soils (either clay or sand) based on the stress history. [...]

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• Drainage Effects in a Dilatant Carbonate Silty Sand

  F. Farzaneganpour, F. Bransby*, C. O’Loughlin

  ISC2024.

  
  

  Abstract

  This paper presents and discusses results from a series of cone, vane and footing tests in a carbonate silty sand, conducted in a geotechnical centrifuge, that investigate how drainage effects scale with the diameter of the device/foundation. The tests involved different penetration and rotational velocities to quantify how velocity influences the drainage response, and in turn, the magnitude of the deduced soil strength. Cone and foundation resistance, and the shear stress measured in the vane tests, were seen to increase with increasing penetration/rotational velocity, consistent with a dilatant shearing response. The collective dataset is interpreted within the ‘drainage backbone curve’ framework, with an attempt made to understand how drainage path length varies for the different devices and is affected by stress level.

  Abstract
  This paper presents and discusses results from a series of cone, vane and footing tests in a carbonate silty sand, conducted in a geotechnical centrifuge, that investigate [...]

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• Site characterisation, data management and data integration for submarine cable landing Projects

  V. Terente, D. HIxman, H. Waterson, M. Wetton*

  ISC2024.

  
  

  Abstract

  There is an increased need for submarine cable infrastructure across the world to serve the offshore wind power industry and the expansion of the submarine interconnectors and telecommunication networks. Cable landfall projects are complex as land, intertidal, nearshore, and offshore environments all coverage, creating an array of dynamic processes, constraints, hazards, and engineering challenges that an asset may face over its lifespan. Robust site characterisation and ground modelling is key for the success of these projects, to allow for the effective, safe, and economical site selection, design, installation, and operation of an asset. In order to accomplish this, the integration of engineering and geoscientific datasets, obtained through several data sources and survey techniques is required; as well as collaboration and integration between multiple technical disciplines. This paper lists the key stages, techniques, and sources available for obtaining the required data. We then consider how the data can be managed and integrated to obtain a holistic ground model for use in the design, construction, and operation of the asset. We discuss the value these models can provide throughout the lifecycle of landfall projects.

  Abstract
  There is an increased need for submarine cable infrastructure across the world to serve the offshore wind power industry and the expansion of the submarine interconnectors [...]

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• Nanotechnology Applied for Soil Stabilization - a Survey

  B. de Córdova Caetani*, H. Nierwinski, B. Karasiak Meneguz

  ISC2024.

  
  

  Abstract

  The technical and constructive challenges inherent to the execution of engineering works on problematic soils require a continuous development or improvement of the techniques and methods used to investigate the soils’ behavior and to design and evaluate the performance of these works. Soil stabilization is one of the most used techniques to improve the mechanical behavior of the soil. In addition to classic soil stabilization methods, nanotechnology is increasingly being used for various purposes, such as introducing nanoparticles of different compounds into the soil mixture or in the field of geosynthetics for fiber treatment. Although they do not have cementing properties, nanoparticles improve mechanical properties, thermal stability, and physicochemical behavior. Studies carried out with different types of soil show that introducing nanoparticles into the soil-cement matrix reduces the space between particles and provides a more robust and rigid soil skeleton. Considering this, it improves the material's resistance properties and reduces cement consumption, contributing to sustainability. The literature review presents research that evaluates different nanoparticles applied to soil mixtures and their influence on the final product. This paper reviews the state of the art of several studies showing that nanotechnology is a successful solution that can be used in soil stabilization because of its capacity to improve, for example, shear strength, unconfined compression strength, and the elastic modulus of soil. The research gap and prospects for using nanotechnology for soil stabilization are also exposed.

  Abstract
  The technical and constructive challenges inherent to the execution of engineering works on problematic soils require a continuous development or improvement of the techniques [...]

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• Organic Soil Identification by CPTu

  C. Champagne*, E. Peuse, R. Hryciw, E. Garcia

  ISC2024.

  
  

  Abstract

  A soil behavior type (SBT) chart was developed to more reliably identify organic soil deposits at sites in the state of Michigan based on piezocone (CPTu) data. Organic soils are often highly compressible organic silts, clays, and peats. Many of these soils are fluvial with high void ratios and large compressibilities. These soils are typically removed prior to the construction of roadways and shallow bridge foundations due to the risk of excessive settlement. CPTu soundings were strategically performed alongside companion soil borings in which standard penetration testing (SPT) was performed and from which split-spoon and Shelby tube samples were recovered and tested. While many of the widely used SBT charts characterize the inorganic soils with reasonable agreement to the soil descriptions presented in the soil boring logs, the organic soils are often mischaracterized as inorganic clays. A hybrid SBT approach was therefore developed that yields more accurate characterization of the organic soils. The inorganic soils are reliably characterized by plotting the normalized tip resistance versus the normalized friction ratio. This SBT approach, however, ignores the valuable piezometric data provided by the CPTu. For organic soils, piezometric data helps to more reliably distinguish between inorganic clays and organic soils. As such, a screening tool was implemented to flag likely organic soils by plotting a parameter that accounts for both the tip resistance and pore pressure versus the normalized friction ratio before characterizing the likely-inorganic soils using existing approaches.

  Abstract
  A soil behavior type (SBT) chart was developed to more reliably identify organic soil deposits at sites in the state of Michigan based on piezocone (CPTu) data. Organic soils [...]

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• Challenges in Site Characterization and Work Verification of Compacted Crushable Sands

  P. Schober, J. Redgers, V. Bhushan*

  ISC2024.

  
  

  Abstract

  During reclamation projects huge amounts of sands are dredged and placed to create artificial land. To increase the density and therefore to mitigate the potential risk of liquefaction as well as to increase the stiffness and internal friction angle of the sand, it is often necessary to compact the reclaimed sand. The performance targets for compaction are frequently verified by means of achieving a particular relative density that is generally correlated from Cone Penetration Tests (CPT). For many reclamation projects, due to the non-availability of local quartz or silica sands, crushable, carbonate or calcareous sands are used. In these crushable sands, due to the very high stress concertation below the CPT cone, the particles tend to crush. The well-known published correlations between the relative density and cone resistance are established for non-crushable silica sands and are thus not applicable to these crushable sands and can result in over treatment costing time and money. Usually, the crushing effect is quantified in a calibration chamber test and a project specific correction factor is introduced. Alternatively, to avoid this costly and time-consuming procedure the use of measuring the shear wave velocity with seismic CPTs (SCPT) is possible. The Cyclic Stress Ratio (CSR) for liquefaction analysis and other soil parameters required for the design verification can be correlated without being influenced by the crushing of particles due to the non-invasive procedure. This paper gives an overview of the common practice for work verification in crushable sand and shows an approach to determine the required compaction parameters using seismic CPTs.

  Abstract
  During reclamation projects huge amounts of sands are dredged and placed to create artificial land. To increase the density and therefore to mitigate the potential risk of [...]

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• Experience of in situ geotechnical tests and their interpretation in organic soils and peat

  M. Long*, G. Tucker, C. Thrane Leth

  ISC2024.

  
  

  Abstract

  This paper reviews the use of piezocone (CPTU) testing to characterise and identify peats and organic soils. Examples of data for peat sites from several countries are given, including some experience of the use of T-bar and piezoball penetrometers in peat. These “full flow” devices show smoother resistance profiles than the equivalent from the CPTU and are perhaps representative of the peat mass with a reduced fibre effect. In CPTU tests, organic soils and peat are often characterised by low corrected cone resistance (qt) and high friction ratio (Rf). CPTU penetration in peat is often drained with data showing low pore water pressure coefficient (Bq) values. Rf broadly decreases with increasing degree of decomposition of the peat. However care needs to be taken in using Rf values in peat given the characteristically very low sleeve friction values (fs) encountered. It would seem that it is not always easy to distinguish between peat and underlying soft soils using CPTU alone. There may be some promise in inclusion of CPTU “add on” sensors particularly a seismic element to yield shear wave velocity (Vs). However there is some uncertainty in measuring Vs in peat both offshore and onshore so care is needed in this regard. Recently developed Soil Behaviour Type (SBT) charts from the Netherlands have also been trialled on several sites. This new formulation shows promise and warrants further study

  Abstract
  This paper reviews the use of piezocone (CPTU) testing to characterise and identify peats and organic soils. Examples of data for peat sites from several countries are given, [...]

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• CPT based classification with focus on organic soils

  A. Lengkeek*

  ISC2024.

  
  

  Abstract

  Most published research on CPT based SBT classification is on mineral soils. Consequently, these classifications do not accurately capture the classification of soft organic clays and peats. Organic soft soils are frequently present within the Holocene deposits in the Netherlands and in other deltaic areas worldwide. Organic soils can be identified by a specific combination of CPT parameters such as a high friction ratio, low cone resistance and low pore pressure response. In contrast to other soft soils, the strength is not necessarily low. This paper presents an updated CPT based classification with focus on organic soils, for the non-normalized SBT chart (Robertson, 2010, Lengkeek et al, 2022) as well as a new classification based on the stress normalized SBT chart (Robertson, 2016). In the new proposed classifications, additional boundaries are set based on the CPT pore pressure measurements, as this appears to be successful to separate organic soils from mineral soils. The performance of the classifications can be quantified by metrics such as the F1 score. The F1 score of the new proposed classifications all show significant improvement.

  Abstract
  Most published research on CPT based SBT classification is on mineral soils. Consequently, these classifications do not accurately capture the classification of soft organic [...]

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