285 results
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2. Soil-water retention behaviour of fine/coarse soil mixture with varying coarse grain contents and fine soil dry densities.
- Author
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Su, Yu, Cui, Yu-Jun, Dupla, Jean-Claude, and Canou, Jean
- Subjects
POTTING soils ,SOIL density ,SOIL drying ,SOIL moisture ,FILTER paper - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
3. Hierarchical response surface method for reliability analysis of a pile-slope system.
- Author
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Zhang, Jie, Wu, Chenguang, Tan, Xiaohui, and Huang, Hongwei
- Subjects
FAILURE mode & effects analysis ,RELIABILITY in engineering - Abstract
Stabilizing piles have been widely used as an effective measure to reinforce slopes. In this paper, a hierarchical response surface method is presented to evaluate the reliability of a pile-slope system efficiently. The suggested method can be used to identify the minimum reliability indexes of different types of failure modes. It can also be used to identify the representative failure modes governing the failure probability of the pile-slope system. This study found that the most critical sliding surface of an unreinforced slope and a reinforced slope is different. It may be nonconservative to design a pile-slope system according to the representative sliding surface of the slope without reinforcements. Even if many failure modes may exist, the reliability index of the pile-slope system is often controlled by several representative failure modes. For the slope examined in this paper, the reliability index of the pile-slope system is controlled by the reliability index of first representative failure mode. The first representative failure mode may vary with the reinforcement ratio, pile length, pile spacing, and location of the piles. The approach presented in this study provides a practical means to quantify the effect of such factors on the design of a pile-slope system. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. A two-dimensional effective stress framework for modelling whole-life soil strength changes due to pore pressure generation and dissipation, Part 2: Applications.
- Author
-
Wang, Yufei, O'Loughlin, Conleth D., Zhou, Zefeng, and Gaudin, Christophe
- Abstract
The accurate quantification of the temporal changes in seabed strength allows for more reliable and less conservative geotechnical design. A recently developed effective stress framework, established within a one-dimensional computational domain to quantify changes in soil strength due to pore pressure generation and dissipation, has been extended to a two-dimensional (2D) computational domain to allow for consideration of boundary value problems that are too complex to be simplified to one-dimensional conditions. The work to implement the 2D framework is reported across two companion papers. The first of the two papers utilises large deformation finite element analyses to quantify the spatial distribution of accumulated plastic shear strain. These distributions are encapsulated within a strain influence function that is used within the new 2D framework in this paper to calculate the extent and magnitude of excess pore pressure, and in turn the mobilised soil strength for a number of boundary value problems that represent typical offshore geotechnical processes. The merit of the new 2D framework is explored via retrospective simulations of existing experimental and numerical data. The resulting comparisons demonstrate the potential of the new framework, which is in quantifying the reliability of a range of geotechnical structures under complex loading conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. A two-dimensional effective stress framework for modelling whole-life soil strength changes due to pore pressure generation and dissipation, Part 1: Formulation.
- Author
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Wang, Y., O'Loughlin, C. D., Zhou, Z., and Gaudin, C.
- Abstract
The undrained shear strength of contractive fine-grained soils changes with time, reducing due to pore pressure generation and increasing during consolidation. There is an increasing appetite to recognise these temporal soil strength changes in offshore geotechnical design, as it provides a basis for potentially less conservative designs. Contributions to this endeavour are reported across two companion papers. This first paper extends an existing effective stress framework that relates the generation of pore pressure to accumulated plastic shear strain, allowing undrained shear strength to be calculated within the context of critical-state soil mechanics. The main development is the extension of the computational domain to two dimensions, allowing calculations to be made for boundary value problems that cannot be satisfactorily simplified to one-dimensional conditions. The magnitude and distribution of accumulated shear strain surrounding objects buried in soil are quantified through a series of large deformation finite element analyses. These spatial distributions are described using a strain influence function in the new 2D framework to calculate the extent and magnitude of excess pore pressure, and in turn the mobilised soil strength around the buried object. The performance of the 2D framework is examined in the companion paper through retrospective simulations of experimental and numerical data. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. LRFD calibration for soil failure limit state using the Stiffness Method.
- Author
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Bathurst, Richard J. and Allen, Tony M.
- Subjects
LOAD factor design ,FAILED states ,BUILDING foundations ,ROAD construction ,BRIDGE design & construction ,BEARING capacity of soils - Abstract
The paper describes load and resistance factor design (LRFD) calibration for the resistance factor used in the Stiffness Method internal stability soil failure limit state for geogrid mechanically stabilized earth (MSE) walls. The Stiffness Method was recently adopted in the current American Association of State Highway and Transportation Officials LRFD Bridge Design Specifications in the US, and will appear in the next edition of the Canadian Highway Bridge Design Code. The paper describes the details of the calibration of the soil failure limit state which is unique to the Stiffness Method. Calibration outcomes include consideration of the concept of level of understanding in the selection of nominal load and resistance values which is unique to LRFD foundation engineering practice in Canada. A practical conclusion from these calculations is that if product line-specific creep test data are available to estimate the reinforcement secant creep stiffness used for design, then a resistance factor of 1.0 is reasonable for US practice. If only minimum average roll value tensile strength data are available, then a value of 0.95 is recommended for US practice. For Canadian practice, the corresponding values for typical level of understanding are 0.90 and 0.85, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
7. Geotechnical performance of fine tailings in an oil sands pit lake.
- Author
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Dunmola, Adedeji, Werneiwski, Robert A., McGowan, Dallas, Shaw, Bill, and Carrier, David
- Subjects
OIL sands ,UNDERWATER photography ,LAKES ,NONLINEAR theories ,SHEAR strength ,STRIP mining ,PETROLEUM pipelines - Abstract
Syncrude Canada Ltd.'s Base Mine Lake (BML), the first commercial-scale demonstration of an oil sands pit lake, was commissioned in December 2012, following in-pit deposition of fine tailings (FT) between 1995 and 2012. The geotechnical design basis for the FT in BML is that it will consolidate and densify over time, contributing to fines sequestration below the water cap. This paper presents the geotechnical performance of the FT in BML within the context of this geotechnical design basis. The FT has settled from 196.0 to 171.6 Mm
3 by 2019, with cumulative settlement varying spatially between 0.3 and 6.7 m. FT settlement is consistent with the expected self-weight consolidation as modeled by finite-strain non-linear consolidation theory, and is reflected as temporal increase in the profiles of solids content and effective stress. Sonar surveying, profile sampling, shear strength, and underwater photography show that the transition of geotechnical properties at the mudline becomes increasingly distinct over time. These observations support the geotechnical design basis for BML and indicate the fines continue to be sequestered below the water cap. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
8. Analytical and numerical models for strain and load calculations for geosynthetic liner systems on steep slopes.
- Author
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Yu, Yan and Rowe, R. Kerry
- Subjects
LANDFILLS - Abstract
The paper develops an analytical model based on the force equilibrium for the design of steep slope geosynthetic liner systems to overcome downdrag loads from waste settlement. This analytical model calculates the required tensile stiffness for a high strength/stiffness geotextile (HS-GTX) reinforcement over the GMB to limit the maximum HS-GTX tensile strain to 5% and the maximum GMB strain to 4% on the side slope. The numerical model illustrates the need for reducing the GMB tensile strains for a single GMB liner on a steep landfill slope and confirms that the use of a HS-GTX over the GMB is able to limit the maximum HS-GTX and GMB tensile strains to the acceptable strain levels. The analytical model developed in this paper is a practical tool for preliminary design to limit tensile strains of the HS-GTX and GMB in a steep slope geosynthetic liner system. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
9. Coupled analysis of soil shear strength and retention curves with different interstitial fluids.
- Author
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Machado, Sandro Lemos, Carvalho, Miriam de Fátima, Vilar, Orencio Monje, and Maedo, Michael Andrade
- Subjects
SHEAR strength of soils ,SOIL testing ,EXTRACELLULAR fluid ,SOIL mechanics ,SLOPE stability - Abstract
Soil shear strength is a fundamental property in analyzing the stability of soil masses in many geotechnical applications, such as slope stability, foundations, and retaining structures. Routinely application considers water as the interstitial fluid composing the soil, however, in some instance other liquids than water can infiltrate the ground due to accidental leakages of fuel and chemical substances. This paper evaluates the influence of fluids of different nature (water, ethanol, and diesel) on the shear strength of compacted specimens of clayey soil, both under saturated and unsaturated conditions. Test results show that the shear strength increases with suction and decreases with the dielectric constant for all the tested liquids. Based on simplified experimental procedures, two coupled models are proposed to reproduce the influence of soil suction and fluid dielectric constant on the soil shear strength and soil liquid retention curve, fairly reproducing experimental results, thus contributing to push unsaturated soil mechanics to geotechnical practice. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
10. Evaluation of small-strain shear modulus of Fontainebleau sand based on innovative pressuremeter probe testing in a calibration chamber.
- Author
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Lopes dos Santos, Alexandre, Dupla, Jean-Claude, Canou, Jean, Puech, Alain, and Cour, Francis
- Subjects
MODULUS of rigidity ,CALIBRATION ,SAND ,TESTING laboratories - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
11. Bayesian estimation of soil-water characteristic curves.
- Author
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Zhang, J., Yang, S., Zhang, L.L., and Zhou, M.L.
- Subjects
MARKOV chain Monte Carlo ,BAYES' theorem ,MONTE Carlo method ,FIX-point estimation - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
12. Thermo-mechanical volume change behavior of municipal solid waste: experimental study and constitutive model.
- Author
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Li, Yu Ping, Chen, Jia Rui, Shi, Jianyong, Li, Xiulei, and Wu, Xun
- Subjects
SOLID waste ,STRAINS & stresses (Mechanics) ,HIGH temperatures ,LANDFILLS ,SILT - Abstract
This paper investigates the thermo-mechanical volume change behavior of municipal solid waste (MSW) by conducting drained heating–cooling tests at constant stresses and isothermal consolidation tests using a temperature-controlled triaxial apparatus. The experimental results show that the compression and swelling indexes of MSW specimen were temperature independent, and the heating-induced volumetric contraction was partially reversible upon cooling. Different from conventional soils, the thermally induced reversible and irreversible volumetric strains of MSW were much larger and stress level dependent. Apart from the experimental study, an isotropic thermo-elastoplastic constitutive model was developed in the framework of existing modified Cam-clay model, which allows the prediction of thermally induced volume changes of MSW. An important feature in this model was the derivation of thermally induced plastic volumetric strain based on the concept of equivalent stress. The capability of the proposed model was validated against the experimental results and showed good predictions. This paper serves as the first attempt to study the thermo-mechanical volume change behavior of MSW, and has provided additional data for the serviceability evaluation of existing pipes as well as settlement and capacity estimation of MSW landfills at elevated temperatures. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
13. The reduction in porosity of permeable reactive barriers due to bio-geochemical clogging caused by acidic groundwater flow.
- Author
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Medawela, Subhani, Indraratna, Buddhima, and Rowe, R. Kerry
- Subjects
PERMEABLE reactive barriers ,GROUNDWATER flow ,CALCITE ,POROSITY ,COLUMNS ,SURFACE area ,WATER filters - Abstract
This study demonstrates the change in porosity of permeable reactive barrier (PRB) material when it reacts with acidic flow. The laboratory column test data obtained over 9 months prove that the porosity of a granular limestone assembly decreases significantly due to bio-geochemical clogging caused by a continuous flow of acidic groundwater. The variations in pH, the pressure measurements, ion concentrations, and the results from X-ray diffraction suggest that clogging at the outlet of the column is much less than at the inlet. About 57% of the total reduction in porosity of the column is attributed to chemical clogging, while the remainder is mainly due to biological clogging. In this paper, a mathematical approach is proposed to estimate the reduction of reactive surface area based on changes in the pore volume. These proposed equations suggest that at the end of experimentation, the dissolution of calcite and bio-geochemical clogging can reduce the total surface area of limestone aggregates by more than 70%. The rigorous approach presented in this paper to determine the dominant clogging component within a granular filter at a given time is vital in estimating the longevity of a PRB and for planning its maintenance. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
14. Slope risk management in light of uncertainty and environmental variability—2021 Canadian Geotechnical Colloquium.
- Author
-
Macciotta, Renato
- Subjects
ROCKFALL ,LANDSLIDES ,CONFERENCES & conventions ,CLIMATE change ,GEOTECHNICAL engineering ,WEATHER - Abstract
Landslides are common across Canada and they pose hazards to human safety, economic activities, and the environment. Robust risk management strategies are necessary for sustainable development. A slope risk management framework has been adopted by the geotechnical community for approximately four decades allowing a systematic, consistent and transparent framework for managing risks. Implementing this framework is associated with uncertainties embedded in our estimates of risk. This paper presents a brief summary of the sources and categories of uncertainty in geotechnical slope engineering and focuses on two topics: (1) estimates of uncertainty in risk calculations and (2) temporal changes in landslide likelihood as a function of weather and steps towards estimating landslide risk changes with climate change. The paper argues that a quantitative risk assessment should not focus on the final risk calculation, but the overall knowledge gained. This allows comprehensive documentation of sources of uncertainty and how they impact geotechnical and risk assessments. Furthermore, the paper outlines approaches to define quantitative correlations between rock fall occurrences and weather, which can be leveraged to estimate changes in rock fall risk with climate change. The paper corresponds to, and expands on, the 2021 Canadian Geotechnical Colloquium. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
15. Vertical seismic response of end-bearing piles in nearly saturated soil.
- Author
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Zheng, Changjie, Yang, Jingquan, Kouretzis, George, and Ding, Xuanming
- Abstract
This paper presents a study on the effect of the degree of saturation of the foundation soil on the vertical seismic response of end-bearing piles subjected to P-waves. The research focuses on nearly saturated soil, where the air phase is not continuous and air bubbles are dissolved in the pore water, and thus can be treated as two-phase material. The response of the two-phase soil–pile system is quantified by means of a rigorous coupled hydromechanical model, which is based on Biot's theory for poroelastic media and treats the air bubbles–pore water mixture as a homogeneous fluid obeying Boyle's law. Numerical results are used to illustrate the influence of the degree of saturation of the soil layer on the seismic strong motion transferred to the pile head, i.e., the capacity of piles to filter seismic wave energy. This work bridges the gap between single-phase and two-phase saturated soil models, which predict profoundly different pile head displacements at incident wave frequencies of practical interest, and elucidates the mechanisms that lead to these differences. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
16. An effective stress-based approach to modeling the chemo-mechanical behavior of saturated active clay.
- Author
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Song, Zhaoyang, Ma, Tiantian, Liu, Yan, Cai, Guoqing, and Wei, Changfu
- Abstract
Pore water chemistry can exert significant controls over the chemo-mechanical behavior of chemically active soils, which has not been characterized by using the traditional Terzaghi's effective stress to a satisfactory extent. In this paper, based on the concept of intergranular stress, a generalized effective stress for saturated active soils is reconceptualized and incorporated into the framework of the modified Cam–Clay (MCC) model to describe the mechanical response of soils upon complex chemical and mechanical loadings. The proposed model is capable of capturing very well the diverse features of the chemo-behavior of saturated active soils, while inheriting all the advantages of the MCC model, by introducing only one additional parameter. Within this context, a simple equation is derived to predict the development of swelling pressure with the variation of pore water chemistry. It is shown that the proposed swelling-pressure equation predicts very well the development of swelling pressure for expansive soils with a dilute pore solution, though discrepancy appears at high concentration. Because the double layer of clay particles is severely suppressed at high salt concentration, the microfabric of soil can be significantly changed, pointing to the importance of taking into account the effect of soil fabric in the constitutive modeling of active soils with high pore water concentration. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
17. Estimation of the hydraulic conductivity of unsaturated soil incorporating the film flow.
- Author
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Zhai, Qian, Ye, Weimin, Rahardjo, Harianto, Satyanaga, Alfrendo, Du, Yanjun, Dai, Guoliang, and Zhao, Xueliang
- Subjects
FILM flow ,SOIL permeability ,HYDRAULIC conductivity ,CAPILLARY flow ,SOIL particles ,SOIL moisture - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
18. Undrained capacity of circular shallow foundations on two-layer clays under combined VHMT loading.
- Author
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He, Pengpeng and Newson, Tim
- Subjects
SHALLOW foundations ,BEARING capacity of soils ,FATIGUE limit ,FINITE element method ,CLAY ,SHEAR strength - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
19. Field tests on large-scale instrumented piles driven in chalk: results and interpretation.
- Author
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Vinck, Ken, Liu, Tingfa, Mawet, Jonathan, Kontoe, Stavroula, and Jardine, Richard J.
- Subjects
CHALK ,TENSION loads ,COMPRESSION loads ,TEST methods ,MOTOR vehicle driving - Abstract
The design of large open steel piles driven at chalk sites suffers from considerable uncertainty, leading to major difficulties in many significant onshore and offshore projects. This paper describes recent instrumented driving, monotonic testing to failure, and restrike tests conducted on large open steel piles driven in primarily low- to medium-density chalk at a site in North-western France. The experiments are described and interpreted with reference to a high-quality site characterisation, dynamic and static methods of test analysis, and alternative predictive design approaches. Important new conclusions flow regarding driving behaviour, the set-up that took place over up to 65 days after installation and the resistances available under compression and tension loading. Surprisingly large differences are shown between tension and compression shaft capacity, which are postulated to be due to Poisson straining in the steel pile shaft and its interaction with the surrounding chalk mass. The field tests contribute to building a high-quality dataset that allows proposed axial capacity design methods to be tested and potentially refined to provide reliable and representative design tools. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
20. A unified critical state parameter model for sand and overconsolidated clay in the framework of subloading surface theory.
- Author
-
Cui, Kai, Wang, Xiaowen, Yuan, Ran, and Liu, Kaiwen
- Subjects
CLAY ,EULER method ,NUMERICAL integration ,SAND ,STRAINS & stresses (Mechanics) ,SOILS ,SAND dunes ,SAND waves ,ELASTIC deformation - Abstract
This paper presents a unified critical state parameter model for evaluating sand and overconsolidated clay, which is named as CASM-S. The model is formulated in terms of the modification of the clay and sand model, i.e., CASM, by incorporating the subloading surface theory with an overconsolidation state parameter R. Although the standard CASM proves to be useful in modelling overconsolidated clay and sand, the model (1) requires the rate of overconsolidated ratio to be constant which is in contrast to the observed behaviour of soils and (2) only allows elastic deformation to develop at the overconsolidated state that may underestimate the deformation corresponding to the peak stress or be unable to predict the actual stress path. By introducing a new material parameter u to those material properties of the standard CASM, the rate relationship of stress–strain for the CASM-S model is developed. The standard CASM can be either recovered or approximated as a special case of the overconsolidation state assumed in the CASM-S. The numerical integration of the newly proposed model is performed by the modified forward Euler method. Validation with undrained and drained overconsolidated clay and sand have demonstrated the capability of the CASM-S model to well predict the observed soil behaviours. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
21. Simulation of cemented paste backfill (CPB) deposition through column experiments: comparisons of field measurements, laboratory measurements, and analytical solutions.
- Author
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Shahsavari, Mohammad, Jafari, Mohammadamin, and Grabinsky, Murray
- Subjects
PORE water pressure ,ANALYTICAL solutions ,MINES & mineral resources ,ELECTRIC conductivity ,ECCENTRIC loads ,SILT - Abstract
Estimating the as-placed properties of mine backfill is fundamental to optimizing the safety and productivity of underground mines. For cemented paste backfill (CPB), an important consideration is the extent to which self-weight consolidation during deposition may reduce the void ratio and enhance the binder's effectiveness. Field monitoring and sampling campaigns can help investigate this phenomenon but they are expensive and logistically difficult. Therefore, mesoscale column experiments are performed in the controlled laboratory environment to better understand the coupling between self-weight consolidation and cement hydration. In this paper, columns are backfilled with uncemented paste tailings and with CPB and the pore water pressure, electrical conductivity, and volume changes are monitored during and after backfilling. The pore water pressure profiles at the end of backfilling are compared with an available analytical solution and restrictions on the solution's validity are identified. Void ratios of samples taken from columns are compared with the ones obtained from field samples and the similarity indicates the filling conditions simulated in the laboratory are representative of field conditions. The changes in void ratio after curing were small compared to the initial void ratio of fresh CPB. The tests' results help explain why self-weight consolidation during backfilling is not significant at the studied mine, which may be the case for many other mining operations as well. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
22. Enhanced estimate of fracture network dimensions by injection of non-Newtonian fluids.
- Author
-
Jaffal, Hamza A. and El Mohtar, Chadi S.
- Subjects
NON-Newtonian fluids ,FLUID injection ,NON-Newtonian flow (Fluid dynamics) ,PSEUDOPLASTIC fluids ,WATER pressure ,ROCK deformation ,FLUID pressure - Abstract
Lugeon tests, also known as water pressure tests, are widely used to estimate the transmissivity of rock-fracture networks and are considered standard testing for grouting of dam foundations. The Lugeon test consists of injecting water into an isolated borehole section intersecting several fractures and monitoring water pressure and flow rate over time to estimate the rock fractures' transmissivity. An average fracture aperture for the whole section is then estimated from the transmissivity value, which is used for selecting the appropriate grout mix. However, the current procedure does not provide any information on the variability in aperture sizes within the investigated rock interval. This paper presents a new approach for performing Lugeon testing that allows for providing a probabilistic distribution of fracture apertures by injecting bio-degradable non-Newtonian fluids at different pressures/flow rates. The theoretical framework demonstrating the ability to estimate the dimensions of multiple fractures, in parallel and in series, from non-Newtonian fluid injection tests is presented. Then, experimental results on different combinations of simple fractures, made of parallel plates, are used to validate the derived model and evaluate its performance. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
23. Analysis of a database of open pit mine slope failures to predict travel distance, setback distance, and geometric properties.
- Author
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Timchenko, Anna and Briaud, Jean-Louis
- Subjects
DATABASES ,SAFETY factor in engineering - Abstract
In mining, open pits have slopes cut as steep as possible to ensure efficient mining yet not too steep to jeopardize safety. Building on existing contributions, the Texas A&M University Mine Slope database (TAMU-MineSlope) was created to provide global-scale insights into the runout mechanics of open pit slope failures and offer the database to engineers for further study. The database includes 134 cases of open pit slope failures that occurred at 76 mines worldwide. Based on energy principles and an analysis of the TAMU-MineSlope data, an equation to predict the travel distance of the slope failure mass is presented in this paper. Furthermore, based on the case histories analysis, an equation to predict the setback distance is proposed. Finally, the TAMU-MineSlope database shows that the average width to height ratio of the failing slope mass is 2.7 and that, for this ratio, the 3D factor of safety (FS) can reach a value 15% higher than the 2D FS. The database has been released in the public domain. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
24. A multi-component model for expansive soils with different mineral compositions.
- Author
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Du, Jiapei, Zhou, Annan, Lin, Xiaoshan, Robert, Dilan J., and Giustozzi, Filippo
- Subjects
SWELLING soils ,SOIL mineralogy ,MOLECULAR dynamics ,CLAY soils ,POTENTIAL energy - Abstract
The accurate prediction of swelling deformation and(or) swelling pressure if confined for expansive soils is essential for a better design and construction of a geotechnical structure that is built on or in an expansive soil. In this paper, we proposed a new method to quantify the swelling strain and(or) swelling pressure of expansive soils by considering the mineralogical components and their different swelling properties. The proposed multi-component model employs a tandem combination of different sub-molecular oedometers for different minerals, and the total swelling strain of soil was calculated by integrating the swelling strain of each mineral. A linear relationship between potential energy and swelling strain is identified based on molecular dynamics' simulation, which is then incorporated into the diffuse double-layer theory to calculate the relationship between confining pressure and swelling strain for each mineral. The numerical model was then validated by experimental results from the literature, which shows a good agreement with the experimental data in the literature. This model provides a cost-effective way to estimate the swelling behavior of expansive soil. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
25. An existing pile efficiency method for the design of lateral new pile behavior in sites with existing piles.
- Author
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Li, Hongjiang and Tamura, Shuji
- Subjects
SUSTAINABLE engineering ,SUSTAINABLE construction ,SUSTAINABLE development ,DESIGN - Abstract
Foundation reuse is the development trend of sustainable engineering construction. However, the reuse of existing piles as rigid inclusions and their contribution to newly constructed piles (new piles) under different new and existing pile spacings are still insufficiently understood. In this paper, a series of numerical investigations were conducted based on centrifuge tests to examine the effect of existing piles on the lateral behavior of new piles under different pile spacings. The existing pile efficiency that reflects the contribution of existing piles to the lateral capacity of new piles was analyzed, and it was shown that the impact of existing piles decays exponentially with the pile spacing between new and existing piles. Beyond the spacing of 6D (D: the diameter of new piles), the lateral new pile–soil–existing pile interaction can be neglected. A parametric study was subsequently performed to quantify the existing pile efficiency under different variables, including the new pile-head restraint, loading displacement, bending stiffness, load eccentricity, embedded depth, and soil properties. Finally, an existing pile efficiency-based method for the estimation of the lateral capacity of new piles was proposed, which provides an efficient way to design laterally loaded new piles in sites with existing piles. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
26. Consolidation-induced improvements in plate anchor capacity.
- Author
-
Wang, C., O'Loughlin, C.D., Bransby, M., Watson, P., and Zhou, Z.
- Subjects
HYPERBOLIC functions ,ANCHORS ,SHEAR strength of soils ,LEAD in soils ,MODELS & modelmaking ,SOIL-structure interaction - Abstract
Plate anchors are an attractive technology for mooring floating facilities; as relative to piles, suction caissons, and drag anchors, they provide a much higher capacity relative to their mass. Plate anchors may experience an extreme loading event that will cause geotechnical failure, although they will still retain a residual capacity. The displacement associated with bringing the anchor to failure will induce excess pore pressures that initially reduce soil strength but will dissipate over time, leading to regains in soil strength and hence anchor capacity. This paper considers the time scales and magnitude of this anchor capacity regain through a series of model scale experiments conducted in a geotechnical centrifuge. The experiments involved vertical loading of pre-embedded horizontally orientated circular anchors in normally consolidated kaolin clay. The results show that anchor capacity regain is a function of consolidation time and the level of resistance maintained on the anchor, with the longest consolidation time and highest maintained resistance leading to a capacity regain of approximately 60%. These capacity increases are described here using a simple hyperbolic function, which provides a basis for estimating the time needed for the residual anchor capacity to regain sufficient capacity following a movement event. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
27. Probabilistic generic transformation model between two rock mass properties: specific fracture energy and P-wave velocity.
- Author
-
Shuku, Takayuki, Phoon, Kok-Kwang, Ishii, Masako, Kumagai, Takeru, Yokota, Yasuhiro, and Date, Kensuke
- Subjects
ROCK properties ,BUILDING sites ,YOUNG'S modulus ,VELOCITY ,FINITE element method - Abstract
This study proposed a probabilistic generic transformation model between two rock mass properties, specific fracture energy, E
v , and P-wave velocity, VP . To build the transformation model, 12 pairwise data sets of Ev and VP were collected from six different construction sites involving construction of mountain tunnels in Japan. This database is labeled as "RockMass/2/350". A probabilistic transformation model was built based on a bivariate standard normal distribution with these 350 data points. The model is generic, because it is based on a variety of sites. The performance of the constructed transformation model was evaluated through a cross-validation. It was found that 98.2% of the validation data fell within the computed 95% confidence interval of the model estimation, and this result provides a preliminary validation of the probabilistic transformation model. Unlike existing deterministic transformation models for estimating VP from Ev , the proposed model can explicitly evaluate the transformation uncertainty with a quantitative metric such as a percentile. For practical application, a 3D model of the spatial distribution for Young's modulus, E, was visualized based on the proposed transformation model. Since the proposed model is probabilistic, it can provide the spatial distribution for percentiles of E values. The constructed 3D model presented in this paper can be directly used as an input data for finite element or finite difference analysis, and probabilistic evaluation of excavation simulation is feasible based on the proposed probabilistic model. The quantitative information on such uncertainty can be useful in decision-making for tunnel constructions, such as selection of a cautious characteristic value. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
28. Monitoring and assessment of a cross-passage twin tunnel long-term performance using wireless sensor network.
- Author
-
Wang, Chao, Friedman, Miles, and Li, Zili
- Subjects
WIRELESS sensor networks ,TUNNELS ,WATER leakage ,QUANTUM tunneling ,SENSOR placement ,EVIDENCE gaps ,STRUCTURAL health monitoring - Abstract
The monitoring and assessment of ageing underground tunnels is critical to ensure their serviceability, stability, and safety as arteries for a transport network in the long term. This paper first comprehensively reviewed the long-term tunnel performance monitoring case studies, aimed at highlighting the limited field monitoring data and identifying research gaps. It was found that previous studies largely focused on the performance of single tunnel sections subject to short-term disturbances (e.g., adjacent excavation), whereas limited efforts concentrated on the long-term performance of twin tunnels, let alone those with cross passages, under the influence of deteriorations. To this end, a Wireless Sensor Network (WSN) was deployed at a critical vehicle cross passage (VCP) twin tunnel section of Dublin Port Tunnel to monitor its long-term ageing performance with time, in addition to the existing long-term water leakage and lining crack monitoring. The evolvement of lining crack and water leakage since 2010 indicated the progressive deteriorations of the monitoring section, and the deployed WSN monitoring of lining inclination demonstrated a robust sensor deployment layout and monitoring plan for (quasi) real-time monitoring for a confined underground cross passage twin tunnel network. An analytical solution was proposed to convert tunnel inclination to horizontal deformation, with the converted measurements suggesting that even more than one decade after construction, both twin tunnels are still moving horizontally towards the VCP centreline in the long term, primarily due to twin tunnel interaction. Along tunnel longitudinal direction, the closer to the VCP, the greater tunnel deformation rate is, revealing the effect of cross passage on tunnel differential longitudinal behaviour, in agreement with hypotheses and numerical results in previous studies. The field observations were believed to be attributed to the two mechanisms which are hydro-geological degradation of the surrounding ground and hydro-mechanical deterioration of the tunnel, where the correlation between tunnel deformation and deteriorations was detailed. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
29. Evaluation of design methods for side-resistance-only rock-socketed piles.
- Author
-
Johnston, Ian W.
- Subjects
EVALUATION methodology ,FORECASTING - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
30. Design of foundations against differential settlement.
- Author
-
Naghibi, Farzaneh and Fenton, Gordon A.
- Subjects
MONTE Carlo method ,SETTLEMENT of structures ,FUNCTION spaces - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
31. Evaluation of candidate polymers to maximize geotechnical performance of oil sands tailings.
- Author
-
Abdulnabi, Ahlam, Amoako, Kwaku, Moran, Daniel, Vanadara, Khushbu, Aldaeef, Abdulghader Abdulrahman, Esmaeilzadeh, Amin, Beier, Nicholas, Soares, João, and Simms, Paul
- Subjects
OIL sands ,POLYMERS ,PIPELINE transportation ,COAGULANTS ,PERMEABILITY - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
32. 2019 Canadian Geotechnical Colloquium: Mitigating a fatal flaw in modern geomechanics: understanding uncertainty, applying model calibration, and defying the hubris in numerical modelling.
- Author
-
Kalenchuk, K.S.
- Subjects
METHODS engineering ,ENGINEERING design ,MATHEMATICAL ability ,ENGINEERING models ,CONFERENCES & conventions - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
33. Limit equilibrium solutions to anti-overturning bearing capacity of suction caissons in uniform and linearly increasing strength clays.
- Author
-
Wu, Yuqi, Yang, Qing, Li, Dayong, and Zhang, Yu
- Subjects
BEARING capacity of soils ,CAISSONS ,FINITE element method ,CLAY ,TORQUE ,EQUILIBRIUM - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
34. Relationship between chain axial resistance and confining stress for South China Sea carbonate sand: an element test.
- Author
-
Guo, Zhen, Zhou, Zefeng, Jostad, Hans Petter, Wang, Lizhong, and Rui, Shengjie
- Abstract
For mooring systems, the relationship between chain axial resistance and confining stress affects the tension transfer of embedded mooring chain, and an effective width parameter E
t was adopted to reflect the complex geometry of the chain. However, the relationship in carbonate sand is fully understood. Designed as an element test, monotonic and cyclic loading tests were conducted to investigate the variation of chain axial resistance with confining stress under different conditions in South China Sea carbonate sand. Peak effective width parameter and secant coefficient were particularly analyzed to describe the gradual mobilization. The results show that the Et value in South China Sea carbonate sand has a mean increase of 15% compared with Pingtan quartz sand, which makes the chain harder to pull into the carbonate sand. The irregular particle shape may contribute to the higher axial resistance. In cyclic tests, the peak post-cyclic Et-m is larger than that of monotonic test under lower confining stress but is smaller under higher stress. This paper provides some references to chain profile prediction in the carbonate sand. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
35. The influence of viscous behavior and static shear stress on the cyclic strengths of plastic soil: a numerical study.
- Author
-
Oathes, Tyler J. and Carey, Trevor J.
- Abstract
An accurate understanding of the cyclic behavior of clays and plastic silts is important for system performance predictions during earthquake loading. This paper presents the results of a numerical investigation into the individual and combined influences of static shear stress and viscous strength gain on the cyclic resistance of clays and plastic silts. Using the viscoplastic constitutive model PM4SiltR implemented in the finite difference program FLAC 8.1, the cyclic behaviors of the plastic soils were simulated using single-element cyclic direct simple shear simulations. A parametric analysis was performed with different combinations of viscous strength gains and static shear stresses. The effects of static shear stress and viscous strength gain varied under monotonic and cyclic loading conditions. Numerical findings suggest empirical correlations developed using scant laboratory data may not accurately predict the reduction of cyclic strengths with increasing static shear stress. Furthermore, sizable magnitudes of monotonic viscous strength gains only produced a marginal increase in cyclic strengths. The findings from this study highlight the need for future experimental laboratory testing to validate the numerical findings, to improve the accuracy of performance predictions of geosystems constructed with clays and plastic silts during and following earthquake loading. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Centrifuge modeling of slope failure induced by elevated gas pressure in wet municipal solid waste landfill.
- Author
-
Hu, Jie, Chen, Yun Min, Li, Jing Hang, Ke, Han, and Li, Jun Chao
- Subjects
SLOPES (Soil mechanics) ,SOLID waste ,FOAM ,LANDFILL gases ,LANDFILLS ,EARTH pressure ,LIQUEFIED gases - Abstract
Understanding triggering mechanisms of slope failure is of great importance to the stability analysis and safety warning of waste landfill. This paper presents a centrifuge model test on slope failure induced by elevated gas pressure in wet landfill. The formation process of liquid level and gas pressure in the landfill is simulated by means of liquid and gas injections under a centrifugal acceleration of 66.7 g. The injected liquid contains surfactants, which allow it to generate foam in the waste pores when mixed with the injected gas. The pore gas and liquid pressures under two-phase flow condition are monitored separately to clarify the instability process. It is found that the continuous gas injection makes the pore gas pressure increase to peak values of 83.0 kPa–100.8 kPa, which are higher than the peak liquid pressures of 61.3 kPa–75.6 kPa. The formation of high gas pressure zone is attributed to the low gas permeability, which is affected by high liquid saturation as well as foam generation. The slope failure occurs when the pore gas pressure increases to the peak value and the corresponding shear strength decreases to the critical value. Although the gas injection raises the liquid level, the factor of safety of landfill slope will be overestimated if only considering the effect of liquid pressure. According to the response curves of displacement to gas pressure rise, the critical ratios of gas pressure to earth pressure are determined to be 0.74–0.84, which fall within the range of the prototype landfill. The difference between foam and air on pore pressure distribution is also calculated and discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. From data to decision: combining Bayesian updating with a data-driven prior to forecast the settlement of embankments on soft soils.
- Author
-
Wan, Xiao and Doherty, James
- Subjects
EMBANKMENTS ,SOIL creep ,SOILS ,BAYESIAN analysis ,RANDOM variables - Abstract
Applications of Bayesian updating commonly treat soil parameters as random variables. A significant issue with this is that soil parameters are highly subjective. Therefore, using traditional parameter-based models, Bayesian analysis starts from a subjective prior and it is unclear how this may influence the overall results of a study. In this paper, Bayesian updating is combined with a data-driven method, known as CRACA (i.e., CReep And Consolidation Analysis), for predicting the settlement of embankments on soft soil. Importantly, the method directly ingests measured oedometer data and, therefore, avoids the subjectivity involved in parameter selection. Because parameters are not used, scaling factors are introduced that account uncertainty associated with the laboratory measurements and the automated interpretation process. These factors have an initial value of unity (returning the prior) and are updated in a Bayesian framework as settlement monitoring data are revealed over time to improve future forecasts. The model was applied to an embankment case history and was shown to result in a rapid improvement in the accuracy and a narrowing of the 95% confidence interval as settlement monitoring data are revealed to the model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. Theoretical framework for predicting accumulation of soil berms and peak sliding resistance for tolerably mobile foundations.
- Author
-
Jia, T., Stanier, S., Watson, P., Feng, X., and Gourvenec, S.
- Subjects
SOILS ,SETTLEMENT of structures ,THERMAL expansion ,SILT ,KAOLIN - Abstract
Tolerably mobile subsea foundations are designed to slide on the seabed to accommodate flowline thermal expansion and contraction, and are a potential alternative to conventional (fixed) foundations. During the periodic sliding events that occur during operation, soil berms form at the extremities of the foundation footprint. The size of the berm increases throughout the life-cycle of the foundation, leading to increasing peak sliding resistance. This may hinder mobility of the foundation and overstress the pipeline connections that the foundation is designed to support. Equally, the berms may be relied on to reduce sliding and thus minimize settlement of the foundation, which can also overstress pipeline connections. This paper analyses the mechanism leading to berm accumulation and its mobilisation, also addressing periodic remoulding and reconsolidation of the sediment in the berm. A framework is proposed to predict the accumulation of soil berms and the resulting peak sliding resistance, and is validated by eight centrifuge model tests performed on a kaolin clay and a calcareous silt. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Calibration of the PM4Sand model for hard-rock mine tailings based on laboratory and field testing results.
- Author
-
Contreras, Carlos Andrés, Yniesta, Samuel, Jahanbakhshzadeh, Abtin, and Aubertin, Michel
- Subjects
TAILINGS dams ,CALIBRATION ,TESTING laboratories ,DYNAMIC simulation - Abstract
A comprehensive campaign of laboratory and field tests has been conducted to characterize the behaviour of tailings from a hard-rock mine. Cyclic triaxial, direct simple shear, and triaxial simple shear tests have shown that the contractive tailings are susceptible to liquefaction and that their behaviour is similar to loose sand despite their higher fines' content. To model the behaviour of tailings' impoundments in dynamic simulations, the PM4Sand constitutive model is calibrated based on the dataset presented here. Some of the model parameters are defined based on consolidation and compression tests, while the critical state line (CSL) is defined based on the results of monotonic triaxial and direct simple shear tests. The CSL is lower for tailings than for most natural sands, which is consistent with previous studies. The calibrated model can reproduce reasonably well the monotonic behaviour and provides an excellent fit of the cyclic strength curves measured in the lab at different confining pressures and density index. The results presented in this paper indicate that the PM4Sand model can be used to simulate the cyclic behaviour of low-plasticity, hard-rock tailings. The proposed procedure also provides general guidelines regarding model calibration for other types of tailings. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
40. Predicting geological interfaces using stacking ensemble learning with multi-scale features.
- Author
-
Wang, Ze Zhou, Hu, Yue, Guo, Xiangfeng, He, Xiaogang, Kek, Hardy Yide, Ku, Taeseo, Goh, Siang Huat, and Leung, Chun Fai
- Subjects
MACHINE learning ,INFRASTRUCTURE (Economics) ,MULTISCALE modeling ,FORECASTING ,INFORMATION processing - Abstract
Understanding the variation of geological interfaces plays a crucial role in the analysis and design of infrastructure systems. Generally, there are two classes of techniques for predicting geological interfaces, for example, interpolation/regression-based techniques and machine-learning-based techniques. In this paper, a Multi-scale Meta-learning Model (M
3 ) methodology is proposed. The new methodology improves the current state-of-the-art techniques by fusing two levels of information: (i) generic characteristics of the sampling locations, for example, coordinates, and (ii) location-specific characteristics, for example, local-scale predictions. The implementation starts from using an array of classic interpolation/regression-based techniques as base learners to provide first-level predictions at a local scale. These predictions are then combined with generic characteristics to train a meta-learner following the stacking ensemble learning framework. In this manner, the location-specific information from the base learners can be simultaneously considered with the generic information in the training process. The variation of rockhead elevation is predicted using the M3 methodology and a comprehensive borehole dataset in Singapore. A detailed comparative study involving several existing methods is also carried out to rigorously validate the M3 methodology. The results show that the M3 methodology achieves 20% improvement in the model performance compared to existing methods, indicating its promising potential in geotechnical site characterization. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
41. Assessment of time effects on capacities of large-scale piles driven in dense sands.
- Author
-
Wen, K., Kontoe, S., Jardine, R.J., Liu, T., Cathie, D., Silvano, R., Prearo, C., Wei, S., Schroeder, F.C., and Po, S.
- Subjects
SAND ,DRIVE shafts ,DYNAMIC testing ,WAVE equation ,WAVE analysis ,STEEL pipe ,LATERAL loads - Abstract
This paper considers the axial resistances of open-ended, highly instrumented, 763 mm diameter steel pipe piles driven in sands for the EURIPIDES (EURopean Initiative on PIles in DEnse Sands) project at a well-characterized research site at Eemshaven, in the northern Netherlands. It offers new analyses of previously unreported dynamic tests and considers their relationship with four heavily instrumented static compression tests. Rigorous signal matching employing two distinct pile–soil interaction models is reported, supported by careful sensitivity analyses, to interpret the recorded driving signals. The back-calculated shaft resistance profiles show good agreement between the models as well as calculations performed with a global wave equation analysis approach. The study highlights the need to account for the internal soil column resistance. The combined interpretation of the dynamic and static test data indicates a 50% gain in shaft resistance over the 10 days after driving and threefold shaft capacity growth over a total period of 533 days after driving. The outcomes have important implications for driven pile design and field quality monitoring; the case history contributes an important benchmark in the study of long-term set-up trends. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
42. X-ray-aided characterization of micro-hydro-mechanical behaviour of unsaturated sand using a suction-controlled mini-triaxial system.
- Author
-
Liu, Jianbin, Leung, Anthony Kwan, Zhou, Chao, and Chen, Rui
- Subjects
X-ray imaging ,IMAGE analysis ,SHEAR strain ,SAND ,X-rays ,PORE fluids ,TEST systems - Abstract
Despite the advancement of the knowledge of unsaturated soil behaviour developed over the past decades, the understandings remain largely at the macro or element scale. Existing testing systems allow simultaneous in situ loading and X-ray imaging to facilitate the studies at micro or pore scale, but the soils of concern are normally two-phase (i.e., dry or saturated). This paper develops a new suction-controlled miniature triaxial apparatus for studying the micro-hydro-mechanical behaviour of three-phase unsaturated soils via in situ quantification of the evolutions of soil microstructures, aided by micro-X-ray computer tomography imaging. The apparatus can independently control combinations of net mean stress and matric suction whilst permitting high-resolution full-field imaging of the entire samples through the image analysis via methods of pore network modelling and discrete digital image correction. Results reveal that at equilibrium, suction at the "transition zone" of the soil does not necessarily mean to have both the air and water phases continuous, as otherwise recognized at the element scale. This phenomenon leads to nonuniform distributions of local void ratio and degree of saturation. Post-peak strain localization and shear band development are explained by the movements of pore fluid and the associated influences on local soil void ratio change. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
43. A cyclic p–y elastoplastic model applied to lateral loaded pile in soft clays.
- Author
-
Cheng, Xinglei, El Naggar, M. Hesham, Lu, Dechun, Wang, Piguang, and Tu, Wenbo
- Subjects
BENDING moment ,CYCLIC loads ,LATERAL loads ,SOIL degradation ,STRAINS & stresses (Mechanics) ,CLAY - Abstract
The p–y method as a simplified analysis tool has been widely used to analyze the behavior of laterally loaded piles. This paper develops a novel cyclic p–y elastoplastic model within the framework of the single-surface bounding surface theory. The model can capture the soil stiffness degradation during cyclic loading by incorporating the cumulative plastic displacement to an interpolation function of the elastoplastic resistance coefficient. The model is relatively simple with only four parameters that can be determined from standard soil properties and stress–strain responses measured in direct simple shear tests. The performance of developed model is validated by predicting the cyclic lateral response of piles installed in soft clay during field and centrifuge tests published in the literature. The model can reliably simulate monotonic and cyclic responses of piles under different lateral loading patterns, and capture main characteristics of the pile-head load–displacement curve, such as nonlinearity, hysteresis, displacement accumulation, and stiffness degradation. It can also predict the evolution of the lateral deflection and sectional bending moment along the pile during cyclic loading. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
44. Numerical implementation and application of an internal state variable model to analyze the time-dependent behavior of mining excavations in rock salt.
- Author
-
Aubertin, Jonathan D., Aubertin, Michel, and Jahanbakhshzadeh, Abtin
- Subjects
ROCK salt ,ROCK excavation ,SALT mining ,STRAIN hardening ,ROCK creep - Abstract
The geomechanical behavior of rock salt has been investigated extensively over the years. Experimental studies have identified distinctive features associated with nonlinear inelastic response that shows strong time and loading history dependencies. In this paper, a relatively simple constitutive model is presented and implemented into the numerical code FLAC, and then applied to analyze the time-dependent behavior of excavations in salt mines. The unified creep-plasticity model includes an internal state variable (ISV) with an evolution law that induces progressive strain hardening (SH) until a steady state is reached. Numerical analyses are performed with the proposed ISV–SH model to evaluate material parameters, based on creep test results on natural rock salt, and to simulate the response of a circular opening and of rectangular mining excavations created in sequence. The results are analysed and compared with those obtained with the well-known Norton power law equation, commonly used in salt mine engineering. The time-dependent calculation results illustrate key aspects of rock salt behavior and highlight the major influence of transient inelastic behavior and stress redistribution on the response of underground openings. The proposed modelling approach constitutes an advantageous alternative to analyses based on stationary creep laws, often used in rock salt mining operations. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
45. Influence of a rigid cap on thermo-mechanical behavior of nonsymmetrical thermally loaded energy pile group in clay.
- Author
-
Zhang, Dingxin, Wang, Chenglong, Bouazza, Abdelmalek, Ding, Xuanming, and Kong, Gangqiang
- Subjects
MECHANICAL loads ,AXIAL loads ,LATERAL loads ,THERMOCYCLING ,CLAY ,ENERGY transfer - Abstract
This paper presents the results of a series of cyclic nonsymmetrical thermally loaded model-scale tests conducted on floating pile groups, with and without a rigid cap in saturated clay. The energy pile in each group was subjected to 10 two-way (heating–cooling) thermal cycles with an amplitude of 15 °C to investigate the potential effects of a rigid cap on the thermomechanical behavior of energy pile groups. It was found that the rigid cap restrained the expansion/contraction of the energy pile in response to temperature change and reduced its irreversible settlement, resulting in a lower differential settlement between the energy and nonenergy piles. Consequently, a lower tilting was observed in the pile group with a rigid cap. In addition, the thermally induced axial load was significantly increased (especially in cooling mode) due to the restriction of a rigid cap. The thermomechanical load transfer profile of the energy pile was also affected by it, resulting in the downward transmission of shaft resistance. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
46. Coupled thermo-hydro-mechanical-chemical modeling of fines migration in hydrate-bearing sediments with CFD-DEM.
- Author
-
Liu, Yajing, Wang, Lizhong, Hong, Yi, and Yin, Zhen-Yu
- Subjects
SIZE reduction of materials ,DISCRETE element method ,COMPUTATIONAL fluid dynamics ,MULTIPHASE flow ,SEDIMENTS ,HYDRAULIC conductivity - Abstract
Fines migration associated with the multiphase flow in the exploitation of hydrate-bearing sediments (HBS) usually induces local clogging and sand production around wells, and thus its behavior with multi-field coupling is of vital importance but still poorly discovered. This paper establishes a coupled thermo-hydro-mechanical-chemical (THMC) model incorporating fines migration in HBS from micro- to macro-scale. Two typical hydrate pore habits, i.e., grain coating and pore filling, are simulated with the discrete element method (DEM) under different depressurization modes, water flow is simulated using computational fluid dynamics (CFD), and heat transfer and chemical reactions are also considered in coupled CFD-DEM simulations. Two distinct fines migration modes and their consequence on the mechanical and hydromechanical properties are revealed. For the grain-coating habit, the coarse particle size reduction induced by hydrate dissociation under an intense depressurization decreases the constriction size, increasing the local pore-clogging probability and reducing the growth rate of the hydraulic conductivity. Conversely, the fine particle size reduction in the pore-filling habit facilitates fines migration and thus sand production, with hydromechanical properties of HBS evolving oppositely compared to the clogging case. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
47. Reliability-based formulation of building vulnerability to debris flow impacts.
- Author
-
Luo, H.Y., Zhang, L.M., He, J., and Yin, K.S.
- Subjects
DEBRIS avalanches ,CONCRETE construction ,REINFORCED concrete ,FLOW velocity ,FAILED states ,IMPACT (Mechanics) - Abstract
Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2022
- Full Text
- View/download PDF
48. Investigation of soil setup effects on pile response in clay considering overconsolidation ratio and installation method through physical modeling.
- Author
-
Fakharian, Kazem, Shafiei, Morteza, and Hafezan, Salar
- Subjects
PILES & pile driving ,CLAY soils ,SOILS ,DEAD loads (Mechanics) ,CLAY - Abstract
The main objective of this paper is investigation of clayey soil setup effects on axial "resistance" and "stiffness" of small-scale piles with special attention on "overconsolidation ratio" (OCR) and "installation method". A consolidation chamber is developed and an instrumented model pile is either driven or jacked-in through saturated consolidated Kaolinite clay at different OCRs of 1.2 (normally consolidated, NC) and 4.8 (over consolidated, OC). The pile was static load tested at different time intervals of 1 h through 90 days. Higher pore pressures are induced during pile installation in NC compared to OC clay. The frictional resistance of OC soil is higher than NC at end of drive as well as end of setup in both driven and jacked-in piles. The frictional resistance of jacked-in piles is greater than driven piles at end of drive, but due to higher rate of setup, the long-term frictional resistance of driven piles is shown to be greater, attributed to more disturbance of the soil during installation of driven piles. Attempts are made to differentiate between the contributions of dissipation of excess pore pressure and non-pore pressure components for each consolidation condition and pile installation method. A relation is proposed to quantify the pile stiffness variations over time due to soil setup. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
49. Performance of a 56 m deep circular excavation supported by diaphragm and cut-off double-wall system in Shanghai soft ground.
- Author
-
Wang, Ruisong, Liu, Shujia, Xu, Longhai, Zhao, Chenyang, Ni, Pengpeng, and Zheng, Weifeng
- Subjects
EXCAVATION ,EARTH pressure ,DIAPHRAGM walls ,WATER levels ,PORE water pressure - Abstract
The performance of a 56 m deep circular excavation supported by a double-wall system, consisting of an inner circular diaphragm wall and an outer rectangular cut-off wall, in Shanghai soft ground is studied in this paper. The surveyed data (e.g., lateral wall deflections (δ
h ), horizontal displacement of soil (δs ), ground surface settlement (δv ), soil rebound (δv+ ), earth pressure (P), pore water pressure (Pw ), and soil stress path) are systematically investigated. The results show that the maximum lateral wall deflections are 0.002% ∼ 0.03% of the excavation depth (He ). The maximum ground surface settlement (δvm ) is generally larger than δhm , which is located at 0.4 ∼ 0.6He . Moreover, an innovative formula is proposed to estimate the ground settlement. It is able to distinguish various characteristics of surface settlement in different zones of the settlement profile. The ground surface settlements are mainly induced by surcharge loading and continuous excavation, and they are related to the change in confined water level. The lateral earth and pore water pressures in the active zone are relatively insensitive to the excavation, while the correlation becomes obvious in the passive zone. The findings from this study can be helpful to the design of other similar deep excavations in soft clay. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
50. Calibration of resistance factors for design of shallow foundations against sliding.
- Author
-
He, Pengpeng and Fenton, Gordon A.
- Subjects
SHALLOW foundations ,LOAD factor design ,SLIDING mode control ,BEARING capacity of soils ,MONTE Carlo method ,WIND pressure - Abstract
The design of shallow foundations typically proceeds by using the load and resistance factor design (LRFD) methodology to avoid various limit states with some probability. This paper looks at the sliding limit state of shallow foundations, and the sliding resistance factors required for the LRFD approach are estimated using reliability analyses of surface strip foundations. Cohesive and frictional soils are separately studied under wind loading conditions. Monte Carlo simulations are used to estimate the sliding failure probability of foundation designs on cohesive soils, and an analytical method is developed for frictional soils. The results indicate the existence of a "worst case" correlation length for cohesive soils, and the sliding resistance factor required to achieve target maximum lifetime failure probabilities is around 0.4–0.65 for moderate soil variability. For frictional soils, the required sliding resistance factor is about 0.5–0.85 for ν
ϕ′ = 0.15. Overall, the sliding resistance factors recommended here agree well with the resistance factors of ϕgu = 0.6 for cohesive soils and ϕgu = 0.8 for frictional soils stipulated by geotechnical LRFD code provisions in Canada. The analyses can be used to estimate the reliability of current designs and can also aid the calibration of geotechnical design codes. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
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