Documents published in Scipedia

• In Situ Measurement of Soil Thermal Properties: a New Prototype

  A. Garcia-Fontanet*

  ISC2024.

  
  

  Abstract

  As part of the THERMALTUNNEL R&D, partially funded by Centro para el Desarrollo Tecnológico e Industrial (CDTI), a Spanish Ministry of Science and Innovation agency, PRO GEO has developed a soil penetration prototype that measures soil temperature and the thermal properties of the ground (thermal conductivity and specific heat) at different depths. The prototype is the size of a conventional CPT and contains an internal heat source with local thermocouples. A data acquisition system measures the temperature both in the prototype itself and in the surrounding ground through a penetration needle protruding from the main body of the prototype. The thermal parameters are determined by analyzing the measured heating and cooling temperature curves using the finite element codes CODE_BRIGHT (Olivella et al., 1993) and G-PFEM (Monforte, 2018). In this later numerical code, a thermal analysis module has been incorporated within the framework of the project. The operation of the prototype has been satisfactory in laboratory tests through a calibration chamber setup with granular soil under different controlled conditions of water saturation and porosity to assess the impact of those variables on the obtained values of soil thermal conductivity and specific heat. The back-analyzed parameters from the calibration chamber results have been compared with point tests (thermal conductivity and specific heat tests). The project has been developed with the cooperation of CIMNE – International Centre for Numerical Methods in Engineering.

  Abstract
  As part of the THERMALTUNNEL R&D, partially funded by Centro para el Desarrollo Tecnológico e Industrial (CDTI), a Spanish Ministry of Science and Innovation agency, PRO [...]

  • 0
  •  read

• Geotechnical investigation of a fissured highly expansive clay profile

  R. Murison, T. Gaspar, S. Jacobsz, G. Heymann, Y. Narainsamy

  ISC2024.

  
  

  Abstract

  This study details some observations and challenges in interpreting site investigation data for highly expansive soils. Expansive soils exhibit large volume changes in response to changes in water content. This leads to a high degree of reworking and often a strongly fissured macrofabric in situ. A site underlain by a ~7.0 m thick active clay deposit, containing highly plastic and highly expansive smectites, was chosen for large-scale pile tests. Two identical areas were identified for the tests. The first was kept at natural water content conditions. The other was kept submerged under water through infiltration wells for six months, aiming to facilitate maximum swell of the active layers. As part of the site investigation, continuous surface wave (CSW) tests and standard penetration tests (SPT) were conducted at various points in time. These results have been compared for the natural water content and the submerged profiles. Small-strain moduli interpreted from the CSW tests showed no significant difference between the two profiles, contrary to the intuitive expectation that inundation of the highly expansive clay layers and dissipation of suctions in the order of several megapascals might significantly reduce the stiffness. Due to the small strains imposed during the test, the characteristics of the fissures and joint infill material are measured, rather than that of the intact masses. The large-strain SPT results showed a softer response for the inundated profile, as expected. Challenges in obtaining intact tube samples from the stiff and highly fissured unsaturated profile have also been discussed.

  Abstract
  This study details some observations and challenges in interpreting site investigation data for highly expansive soils. Expansive soils exhibit large volume changes in response [...]

  • 0
  •  read

• Characteristics of the Electroresistivity of a compacted Iron Ore Tailing

  F. Marinho, B. Dos Santos, J. Da Silva*, B. Delgado, M. Hora

  ISC2024.

  
  

  Abstract

  The new legislation in Brazil has brought more attention to the technique of stacking filtered iron ore tailings for mining waste disposal. To minimize the risk of liquefaction, it's important to maintain the compacted structure in an unsaturated condition. This requires knowledge of the hydraulic characteristics of the material in order to evaluate the long-term performance of the embankment and design an adequate monitoring system. One way to track the material's behavior in the field is through electrical resistivity techniques. Using an electrical resistivity measurement system at various frequencies and current levels, we evaluated the behaviour of compacted iron ore waste. The examined tailings have been deposited in filtered tailings piles, which are intended to exceed a height of 100 meters. This study aims to investigate the electrical response of the material to different levels of water content, degree of saturation and suction. It was possible to establish good correlations between electrical resistivity and factors such as suction, degree of saturation, and water content. It was also identified an association between the electrical resistivity and the optimum water content

  Abstract
  The new legislation in Brazil has brought more attention to the technique of stacking filtered iron ore tailings for mining waste disposal. To minimize the risk of liquefaction, [...]

  • 0
  •  read

• In Situ Test Methods for Thermal Site Characterisation – A Comparison

  L. Vrielink*, J. Peuchen, N. Parasie

  ISC2024.

  
  

  Abstract

  The demand for thermal site characterization has risen noticeably in the past decade, particularly for design of geothermal energy solutions and for design of in-ground power cable networks. The results of thermal characterization of a site are typically incorporated in a ground model based on environmental, geological, geophysical and geotechnical geodata. This paper compares in-situ test methods for thermal site characterization of soil. The comparison considers method applicability, deployment method, maximum test depth, test duration and uncertainty of results. A distinction is made between three categories of in-situ tests: (1) in-situ tests using active heat generation, (2) in-situ tests using passive heat generation and (3) in-situ tests with no specific thermal data acquisition

  Abstract
  The demand for thermal site characterization has risen noticeably in the past decade, particularly for design of geothermal energy solutions and for design of in-ground power [...]

  • 0
  •  read

• Use of geosynthetics to close a contaminated area in a metallurgical industry in the state of bahia

  T. Andrade, I. Silva, L. Rezende, D. Eloi*, M. Neto

  ISC2024.

  
  

  Abstract

  The study for closure and monitored natural attenuation/stabilization of industrial waste deposits plays a fundamental role in the process of groundwater quality management, providing information for understanding the contaminants evolution and enabling decision-making, with the purpose of isolating waste, contaminant concentrations, toxicity and mass and/or volume reduction to levels adequate to protect human health and the environment, within a reasonable period of time. The aim of this study was to propose an environmental remediation solution for a contaminated material disposal area using the case study of a metallurgical industry located in Bahia, Brazil. To this purpose, four conditions were provided for compliance: i) control of dust, odor and erosion, ii) control of contaminant release, iii) chemical stabilization of waste and iv) soil recovery. Based on the results obtained in environmental investigation studies and information from the area, the best solution in an attempt to naturally stabilize the area would be the use of geosynthetics as a physical barrier between the contaminated material disposed in the area and the rainwater. In this way, infiltration of rainwater into the landfill and the migration of percolated liquid with risk of contamination to the soil, groundwater table and surface water bodies is avoided. It is still possible to monitor the effectiveness of the proposed solution with the installation of instrumentation such as water level indicators and piezometers.

  Abstract
  The study for closure and monitored natural attenuation/stabilization of industrial waste deposits plays a fundamental role in the process of groundwater quality management, [...]

  • 0
  •  read

• Interpretation of CPTu data using machine learning techniques to develop the ground model of a dam

  M. Sottile*, J. Crocker, L. Roldan

  ISC2024.

  
  

  Abstract

  Building a ground model through manual processes can be time consuming, as large amounts of data need to be classified to define the extent and spatial distribution of the different soil materials. This paper delves into the application of machine learning (ML) methodologies, in conjunction with in-situ geotechnical testing data, to develop the ground model for a downstream dam founded on both weak and liquefiable soils. The dam covers a linear extent of approximately 800 m and was extensively characterized by means of in-situ tests, including 206 cone penetration tests (CPTu), 37 boreholes and 35 test pits. The performance of two unsupervised ML clustering algorithms are compared: Density-Based Spatial Clustering of Applications with Noise (DBSCAN) and an extended version with a hierarchical component (HDBSCAN). The clustering uses CPTu data, which consists of the normalized cone tip resistance (Qtn) and the normalized sleeve friction (Fr) varying with elevation. Nearby borehole logs are used to evaluate the results of both clustering methods for a single single CPTu sounding using different clustering parameters. Then, a global clustering including several CPTu soundings is done and results are compared with the ground model that was manually made using Leapfrog software. Both methods show very good performance, with HDBSCAN being better and more robust.

  Abstract
  Building a ground model through manual processes can be time consuming, as large amounts of data need to be classified to define the extent and spatial distribution of the [...]

  • 0
  •  read

• Cyclic Cone Penetrometer Tests: Worthwhile?

  C. O'Loughlin*, F. Bransby, S. Mani, B. Bienen, P. Esfeh

  ISC2024.

  
  

  Abstract

  This paper explores the merit of including cyclic episodes in cone penetrometer tests to measure changes in sleeve resistance during cycling. Tests were carried out in a geotechnical centrifuge in a kaolin clay and a dense silica sand. The data from the tests in clay indicate that the cone sleeve mobilises the remoulded undrained shear strength during the initial penetration, but that with continued cycling, the mobilised interface shear strength reduces to around one-third of the remoulded undrained shear strength before increasing. The initial reduction is considered to be due to local consolidation around the cone sleeve (leading to total stress reduction), whereas the subsequent increase is attributed to consolidation- induced strength hardening. Tests in sand also indicate a reduction in sleeve friction during cycling, consistent with the shear band contraction mechanism associated with friction fatigue of piles in sand, but with no consolidation-induced hardening behaviour as these tests were drained. The findings suggest that cyclic cone penetrometer tests may be a convenient means of gathering data for geotechnical design for problems where the cyclic response at the clay/structure interface is of interest. Considerations on the implications for offshore site investigations are provided.

  Abstract
  This paper explores the merit of including cyclic episodes in cone penetrometer tests to measure changes in sleeve resistance during cycling. Tests were carried out in a geotechnical [...]

  • 0
  •  read

• Geotechnical Characterization of Dredged Material from Rio Grande’s Port, Brazil

  I. Soares Ribeiro*, H. Nierwinski, D. Freitas Fagundes, R. Pinheiro Maria

  ISC2024.

  
  

  Abstract

  Dredging works are essential to ensure navigability in Harbors and waterways. However, this crucial activity generates millions of tonnes of waste each year worldwide. Since the disposal of dredged material is responsible for several environmental impacts, entrepreneurs and engineers must find creative uses for it. Therefore, this study aims to characterize a local dredged material to assess its properties and suitability for geotechnical applications. With this knowledge, this paper presents a series of experimental tests on dredged material samples retrieved from Rio Grande's Port, Brazil. The experimental program includes determining Atterberg limits, sieve and sedimentation analysis, pH and SEM analysis, compaction curve, and unconfined compressive strength in a reconstituted state. The results showed that the material is sandy lean clay, with unfavourable strength characteristics for geotechnical work in a raw state. However, with the advent of chemical stabilization techniques, there is potential for enhancing its suitability for geotechnical applications. By exploring methods such as adding binders like lime or Portland cement, the material's strength and stability could be significantly improved, opening up possibilities for its utilization in various engineering projects. This study contributes valuable insights into the potential reclamation and beneficial reuse of dredged material, ultimately aiding in the sustainable management of harbor and waterway dredging operations

  Abstract
  Dredging works are essential to ensure navigability in Harbors and waterways. However, this crucial activity generates millions of tonnes of waste each year worldwide. Since [...]

  • 0
  •  read

• When Did Geotechnical Data Become A Point Of View: A Case Of Numerical Analysis Vs Site Data

  B. Look*

  ISC2024.

  
  

  Abstract

  The construction of a permanent bridge required a temporary bridge parallel to the permanent bridge alignment. Preloading of the permanent bridge abutment occurred under a separate early earthworks contract. That fill was removed, and the temporary structure was constructed. The fill was then replaced behind the abutment. Movement of the southern abutment of the permanent bridge was identified but with a gap of several weeks in survey monitoring due to a XMAS break period. The abutment had moved towards the river and temporary bridge. Potential causes for movement were investigated by additional investigation adjacent to and far away from the temporary bridge piles. Post movement tests carried out included: Dilatometer Testing (DMT) to assess for shear zones (if any) for slope instability, Cone Penetration Testing (CPTu) to assess strength changes (if any) to proximity of piles and new inclinometer readings. INSAR data was also obtained. A 3-D finite element analysis (FEA) carried out by a consultant matched the measured lateral displacements at the adjacent bridge. Based on that correlation, it was concluded that the removal of the close-ended temporary piles was the main cause of the excessive movement, and this initiated a contractual claim. Correlation is not causation. This case study provides a background on the site data and numerical analysis. The FEA did not include much of the site observational and site data post movement. Given the FEA was given the same credence as the site data, this suggests that data is now considered a point of view.

  Abstract
  The construction of a permanent bridge required a temporary bridge parallel to the permanent bridge alignment. Preloading of the permanent bridge abutment occurred under a [...]

  • 0
  •  read

• A CT-based approach to assess sample quality in soft soils

  J. Pineda*, N. Sau, K. Ouyang, M. Arroyo

  ISC2024.

  
  

  Abstract

  The paper discusses the performance of a novel tool based on computed tomography (CT) to evaluate sample quality in soft soils. This new technique is applied to the low-plasticity Mediterranean deltaic deposits found in the region of Castello d’Empuries at the Costa Brava, in Catalonia (Spain). Tube specimens of variable diameters retrieved using open samplers (Shelby) as well as Osterberg-type fixed-piston samplers were scanned in this study. Statistical analysis of the CT images allows to define a quantitative index of sample quality. Sample quality classification based on this new non-destructive CT-based measure compares well with quality classification based on the well-established recompression sample quality index, e/e0.

  Abstract
  The paper discusses the performance of a novel tool based on computed tomography (CT) to evaluate sample quality in soft soils. This new technique is applied to the low-plasticity [...]

  • 0
  •  read