The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
David E. Elrick - One of the best experts on this subject based on the ideXlab platform.
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Water movement in a finite layer : influence of gravity for Constant Water Content at the surface
Journal of Hydrology, 1994Co-Authors: J.-y. Parlange, U. Hornung, W. L. Hogarth, L. D. Connell, R. Peters, Carlos Fuentes, Randel Haverkamp, David E. ElrickAbstract:Abstract The flow of Water in a finite soil layer is analyzed with gravity, extending an earlier non-gravitational theory. Analytical approximations are obtained to predict the outflow at the lower surface when the potentials at the upper and lower surfaces are fixed. The accuracy of the predictions is checked by comparison with numerical simulations. The solution should be of importance to infer soil properties from outflow measurements in laboratory experiments. The time when outflow first begins and the steady state flow rate are especially useful for that purpose.
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An analysis of solute accumulation during steady-state evaporation in an initially contaminated soil
Journal of Hydrology, 1994Co-Authors: David E. Elrick, André Mermoud, Thierry MonnierAbstract:Abstract The convective dispersion equation is often used as a functional description of solute transport in soils. In this paper the problem of salt or chemical accumulation near the soil surface under the conditions of an upward evaporative flux is solved analytically for both a Constant Water Content and a depth-dependent Water Content that is invariant with time. The depth-dependent Water Content profile is obtained by use of the Gardner solution for steady-state evaporation from a shallow Water table. It is shown that under the conditions encountered in the Valais Canton, Switzerland, the concentration profile that develops with time under steady-state evaporative conditions from a shallow Water table can be obtained with sufficient accuracy for field conditions using a Constant Water Content. The concentration profile which develops with time depends upon both the upward evaporative flux of Water, which concentrates solutes at the surface, and the diffusive-dispersive flux, which tends to move solutes downward against the upward flux of Water. Examples illustrate the influence of velocity and dispersion effects on the solute profiles.
Sai K. Vanapalli - One of the best experts on this subject based on the ideXlab platform.
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Modelling virgin compression line of compacted unsaturated soils
Acta Geotechnica, 2019Co-Authors: Zhong Han, Sai K. Vanapalli, Wei-lie Zou, Xie-qun Wang, Jun-feng ZhangAbstract:In this paper, the volumetric collapse of an unsaturated soil, upon soaking to saturation under a certain stress level, is referred to as soaking collapse. The soaking collapse for a soil under virgin condition is assumed equal to the difference between the soil’s virgin compression line (VCL) and its normal consolidation line (NCL) at saturated condition based on results of oedometric Constant Water Content compression and soaking tests performed on a compacted Nanyang expansive clay. A one-parameter model is proposed to describe the variation of the soaking collapse with the pre-soaking degree of saturation under virgin condition once (1) a soil’s yielding point can be clearly defined and (2) the degree of saturation during virgin compression is known. This model can be used to predict the VCL from the NCL. Data of the Nanyang expansive clay, along with published data of nine soils that were derived from Constant Water Content or Constant suction compression tests (including oedometric and triaxial compression), were used to calibrate and validate the model. It is shown that the model, when combined with a degree of saturation-volume model and the information of yielding and NCL, can predict reasonable VCLs for all examined soils and suitably capture several characteristics of the VCL including the nonlinearity and pressurised saturation. A Constant model parameter of 1.5 is found suitable for all examined soils. The model is also used to predict the VCLs of two compacted soils from the Constant degree of saturation compression, which is a recently developed testing technique to evaluate the compression behaviour of unsaturated soils, with reasonable agreement achieved.
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Predicting volumetric behavior of compacted clays during compression
Applied Clay Science, 2018Co-Authors: Wei-lie Zou, Sai K. Vanapalli, Zhong Han, Jun-feng Zhang, Gui-tao ZhaoAbstract:Abstract Compacted clays are one of the most frequently used materials in the construction of geotechnical infrastructure. Clays, after compaction, typically stay in an unsaturated condition. Their volumetric behavior is the key information for the geotechnical design but is quite complicated to describe or predict due to the coupled hydro-mechanical interplay among the solid, Water and air phases. This paper proposes a model for predicting the volumetric behavior of compacted unsaturated clays during compression (compression line), which consists of the pre-yielding elastic deformation (recompression line) as well as the post-yielding elastoplastic deformation (normal compression line). The model is convenient to use as it only requires limited soil information to calibrate, including the conventional saturated compression line and one unsaturated compression line. Experimental investigation was conducted to determine the volumetric behavior of a compacted expansive clay collected from Nanyang, China during Constant Water Content compression. The performance of the proposed model is reasonably validated against the testing data of the expansive clay, as well as literature data of several clays obtained from Constant Water Content or Constant suction compression. It is demonstrated that the model predictions are capable of capturing the non-linear characteristics of the unsaturated compression lines and allow smooth transitions (i) from elastic deformation to elastoplastic deformation at yielding (gradual yielding) and (ii) from unsaturated condition to saturated condition at high stress level (pressurized saturation).
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Mechanical Behaviour of a Compacted Residual Soil of Gneiss from Brazil under Constant Water Content Condition
Indian Geotechnical Journal, 2016Co-Authors: Orlando Martini De Oliveira, Fernando A. M. Marinho, Sai K. VanapalliAbstract:Compacted fine-grained soils are widely used in the construction of geotechnical infrastructures such as the embankments, retaining walls and pavements. These infrastructures are typically constructed at a relatively fast rate such that the pore-Water phase is not allowed to drain, or under Constant Water Content (CW) condition. The mechanical behaviour of compacted fine-grained soils under CW condition should be well understood in addition to various other loading conditions for rational design of geotechnical infrastructures. In this study, compacted soil specimens of a residual gneiss from Brazil were tested using a conventional triaxial testing equipment under CW condition. A high capacity tensiometer was used to measure the matric suction in the compacted soil specimens. Three groups of soil specimens compacted at different initial Water Contents representing dry of optimum, optimum and wet of optimum conditions were tested to study the influence of soil structure on the matric suction development in the soil specimens during testing. The test results suggest that the matric suction changes in the soil under CW condition depend mainly on the volume change behavior, which is influenced by the level of confining pressure, the degree of saturation and the soil structure. The simple conventional triaxial testing equipment has been found to be useful for determining the mechanical behavior of compacted fine-grained soils under CW condition with the aid of a high capacity tensiometer.
John S. Mccartney - One of the best experts on this subject based on the ideXlab platform.
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Application of Hysteretic Trends in the Preconsolidation Stress of Unsaturated Soils
Geotechnical and Geological Engineering, 2017Co-Authors: Woongju Mun, C. J. R. Coccia, John S. MccartneyAbstract:This paper involves an evaluation of a relationship describing the evolution in yield stress of unsaturated soils during hydraulic hysteresis, and an application of this relationship in an elasto-plastic framework to predict the compression curves of unsaturated soils under drained (free outflow of air and Water with Constant suction) or undrained (Constant Water Content with no outflow of Water and varying suction) conditions. The yield stress was quantified as the apparent mean effective preconsolidation stress obtained from compression tests reported in the literature on specimens that had experienced different hydraulic paths. It was observed that the preconsolidation stress does not follow a hysteretic path when plotted as a function of matric suction, but does when plotted as a function of the degree of saturation. Accordingly, an existing logarithmic relationship between the preconsolidation stress and matric suction normalized by the air entry suction was found to match the experimental preconsolidation stress results. This same relationship was also able to satisfactorily predict the trends in preconsolidation stress with degree of saturation by substituting the hysteretic soil–Water retention curve (SWRC) into the place of the matric suction. The relationship between preconsolidation stress and suction was combined with an elasto-plastic framework to predict the compression curves of soils during drained compression, while the wetting-path relationship between preconsolidation stress and degree of saturation was combined with the framework to predict the compression curves of soils during undrained (Constant Water Content) compression. A good match was obtained with experimental data from the literature, indicating the relevance of considering the hysteretic SWRC and preconsolidation relationships when simulating the behavior of unsaturated soils following different hydro-mechanical paths.
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Impact of Strain Rate on the Shear Strength and Pore Water Pressure Generation of Saturated and Unsaturated Compacted Clay
Geo-Congress 2014 Technical Papers, 2014Co-Authors: Jenna S. Svoboda, John S. MccartneyAbstract:A series of consolidated-undrained (Constant Water Content) triaxial compression tests were performed on compacted low plasticity clay under saturated and unsaturated conditions. The purpose of the test series was to evaluate the impact of strain rate and initial suction on the undrained shear strength of the clay. Consistent with trends in the literature, the shear strength of saturated clay increased at approximately 13% per log cycle of decreasing time to 15% axial strain. The excess pore Water pressure at failure measured at the bottom boundary of the specimen was found to decrease with increasing strain rates for saturated specimens but increase for unsaturated specimens. The rate of increase in the shear strength of unsaturated clays having suction values up to 140 kPa (degrees of saturation greater than 85%) was found to be greater than that of the clay under saturated conditions.
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Nonisothermal Shear Strength of Compacted Silt under High Suction Magnitudes
Unsaturated Soils: Research and Applications, 2012Co-Authors: Nahed A. Alsherif, John S. MccartneyAbstract:This study focuses on a preliminary evaluation of the peak shear strength of compacted silt under high suction magnitudes and temperatures, which are relevant conditions encountered when using heat exchangers to improve the mechanical response of compacted soil layers. Specifically, a series of Constant Water Content triaxial tests were performed on specimens which had reached equilibrium with saturated salt solutions in insulated desiccators having controlled temperatures ranging from 24 to 65 °C. Results from these tests indicate that increased temperature leads to a slight increase in the peak shear strength of soils having a given initial total suction. The total suction has a greater impact on the peak shear strength of soils than temperature, which indicates that heat exchangers may be a suitable tool to increase the strength of compacted soils.
Jun-feng Zhang - One of the best experts on this subject based on the ideXlab platform.
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Modelling virgin compression line of compacted unsaturated soils
Acta Geotechnica, 2019Co-Authors: Zhong Han, Sai K. Vanapalli, Wei-lie Zou, Xie-qun Wang, Jun-feng ZhangAbstract:In this paper, the volumetric collapse of an unsaturated soil, upon soaking to saturation under a certain stress level, is referred to as soaking collapse. The soaking collapse for a soil under virgin condition is assumed equal to the difference between the soil’s virgin compression line (VCL) and its normal consolidation line (NCL) at saturated condition based on results of oedometric Constant Water Content compression and soaking tests performed on a compacted Nanyang expansive clay. A one-parameter model is proposed to describe the variation of the soaking collapse with the pre-soaking degree of saturation under virgin condition once (1) a soil’s yielding point can be clearly defined and (2) the degree of saturation during virgin compression is known. This model can be used to predict the VCL from the NCL. Data of the Nanyang expansive clay, along with published data of nine soils that were derived from Constant Water Content or Constant suction compression tests (including oedometric and triaxial compression), were used to calibrate and validate the model. It is shown that the model, when combined with a degree of saturation-volume model and the information of yielding and NCL, can predict reasonable VCLs for all examined soils and suitably capture several characteristics of the VCL including the nonlinearity and pressurised saturation. A Constant model parameter of 1.5 is found suitable for all examined soils. The model is also used to predict the VCLs of two compacted soils from the Constant degree of saturation compression, which is a recently developed testing technique to evaluate the compression behaviour of unsaturated soils, with reasonable agreement achieved.
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Predicting volumetric behavior of compacted clays during compression
Applied Clay Science, 2018Co-Authors: Wei-lie Zou, Sai K. Vanapalli, Zhong Han, Jun-feng Zhang, Gui-tao ZhaoAbstract:Abstract Compacted clays are one of the most frequently used materials in the construction of geotechnical infrastructure. Clays, after compaction, typically stay in an unsaturated condition. Their volumetric behavior is the key information for the geotechnical design but is quite complicated to describe or predict due to the coupled hydro-mechanical interplay among the solid, Water and air phases. This paper proposes a model for predicting the volumetric behavior of compacted unsaturated clays during compression (compression line), which consists of the pre-yielding elastic deformation (recompression line) as well as the post-yielding elastoplastic deformation (normal compression line). The model is convenient to use as it only requires limited soil information to calibrate, including the conventional saturated compression line and one unsaturated compression line. Experimental investigation was conducted to determine the volumetric behavior of a compacted expansive clay collected from Nanyang, China during Constant Water Content compression. The performance of the proposed model is reasonably validated against the testing data of the expansive clay, as well as literature data of several clays obtained from Constant Water Content or Constant suction compression. It is demonstrated that the model predictions are capable of capturing the non-linear characteristics of the unsaturated compression lines and allow smooth transitions (i) from elastic deformation to elastoplastic deformation at yielding (gradual yielding) and (ii) from unsaturated condition to saturated condition at high stress level (pressurized saturation).
Wei-lie Zou - One of the best experts on this subject based on the ideXlab platform.
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Modelling virgin compression line of compacted unsaturated soils
Acta Geotechnica, 2019Co-Authors: Zhong Han, Sai K. Vanapalli, Wei-lie Zou, Xie-qun Wang, Jun-feng ZhangAbstract:In this paper, the volumetric collapse of an unsaturated soil, upon soaking to saturation under a certain stress level, is referred to as soaking collapse. The soaking collapse for a soil under virgin condition is assumed equal to the difference between the soil’s virgin compression line (VCL) and its normal consolidation line (NCL) at saturated condition based on results of oedometric Constant Water Content compression and soaking tests performed on a compacted Nanyang expansive clay. A one-parameter model is proposed to describe the variation of the soaking collapse with the pre-soaking degree of saturation under virgin condition once (1) a soil’s yielding point can be clearly defined and (2) the degree of saturation during virgin compression is known. This model can be used to predict the VCL from the NCL. Data of the Nanyang expansive clay, along with published data of nine soils that were derived from Constant Water Content or Constant suction compression tests (including oedometric and triaxial compression), were used to calibrate and validate the model. It is shown that the model, when combined with a degree of saturation-volume model and the information of yielding and NCL, can predict reasonable VCLs for all examined soils and suitably capture several characteristics of the VCL including the nonlinearity and pressurised saturation. A Constant model parameter of 1.5 is found suitable for all examined soils. The model is also used to predict the VCLs of two compacted soils from the Constant degree of saturation compression, which is a recently developed testing technique to evaluate the compression behaviour of unsaturated soils, with reasonable agreement achieved.
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Predicting volumetric behavior of compacted clays during compression
Applied Clay Science, 2018Co-Authors: Wei-lie Zou, Sai K. Vanapalli, Zhong Han, Jun-feng Zhang, Gui-tao ZhaoAbstract:Abstract Compacted clays are one of the most frequently used materials in the construction of geotechnical infrastructure. Clays, after compaction, typically stay in an unsaturated condition. Their volumetric behavior is the key information for the geotechnical design but is quite complicated to describe or predict due to the coupled hydro-mechanical interplay among the solid, Water and air phases. This paper proposes a model for predicting the volumetric behavior of compacted unsaturated clays during compression (compression line), which consists of the pre-yielding elastic deformation (recompression line) as well as the post-yielding elastoplastic deformation (normal compression line). The model is convenient to use as it only requires limited soil information to calibrate, including the conventional saturated compression line and one unsaturated compression line. Experimental investigation was conducted to determine the volumetric behavior of a compacted expansive clay collected from Nanyang, China during Constant Water Content compression. The performance of the proposed model is reasonably validated against the testing data of the expansive clay, as well as literature data of several clays obtained from Constant Water Content or Constant suction compression. It is demonstrated that the model predictions are capable of capturing the non-linear characteristics of the unsaturated compression lines and allow smooth transitions (i) from elastic deformation to elastoplastic deformation at yielding (gradual yielding) and (ii) from unsaturated condition to saturated condition at high stress level (pressurized saturation).