Dépouillements

Reliability assessment of basal-heave stability for braced excavations in clay / A. T. C. Goh in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 145–153 Titre : Reliability assessment of basal-heave stability for braced excavations in clay Type de document : texte imprimé Auteurs : A. T. C. Goh, Auteur ; F. H. Kulhawy, Auteur ; K. S. Wong, Auteur Année de publication : 2008 Article en page(s) : pp. 145–153 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Bracing  Excavation  Clays  Safety  Retaining  walls  Structural  reliability Résumé : One potential failure mechanism that needs to be considered for the design of braced excavations in soft clays is basal-heave instability. Many uncertainties are associated with the calculation of the basal-heave factor of safety, including the variabilities of the loadings, geotechnical soil properties, and engineering and geometrical properties of the wall. A risk-based approach to failure is necessary to incorporate systematically the uncertainties associated with the various design parameters. This paper demonstrates the potential for the reliability index–based approach for evaluating the basal-heave stability of braced excavations in clay. By using basic structural reliability concepts that reflect the degree of uncertainty of the underlying random variables in the analyses, engineers will have increased awareness of the uncertainties and their effects on the probability of failure. This study shows that the assumption of a linear limit state (failure) surface can be used to provide reasonable estimates of the reliability index and the probability of failure. Mathematical expressions, tables, and charts have been provided to estimate the probability of basal-heave failure for wide and deep excavations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2814 [...] [article] Reliability assessment of basal-heave stability for braced excavations in clay [texte imprimé] / A. T. C. Goh, Auteur ; F. H. Kulhawy, Auteur ; K. S. Wong, Auteur . - 2008 . - pp. 145–153. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 145–153 Mots-clés : Bracing  Excavation  Clays  Safety  Retaining  walls  Structural  reliability Résumé : One potential failure mechanism that needs to be considered for the design of braced excavations in soft clays is basal-heave instability. Many uncertainties are associated with the calculation of the basal-heave factor of safety, including the variabilities of the loadings, geotechnical soil properties, and engineering and geometrical properties of the wall. A risk-based approach to failure is necessary to incorporate systematically the uncertainties associated with the various design parameters. This paper demonstrates the potential for the reliability index–based approach for evaluating the basal-heave stability of braced excavations in clay. By using basic structural reliability concepts that reflect the degree of uncertainty of the underlying random variables in the analyses, engineers will have increased awareness of the uncertainties and their effects on the probability of failure. This study shows that the assumption of a linear limit state (failure) surface can be used to provide reasonable estimates of the reliability index and the probability of failure. Mathematical expressions, tables, and charts have been provided to estimate the probability of basal-heave failure for wide and deep excavations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2814 [...]

Uplift mechanisms of pipes buried in sand / C. Y. Cheuk in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 154–163 Titre : Uplift mechanisms of pipes buried in sand Type de document : texte imprimé Auteurs : C. Y. Cheuk, Auteur ; D. J. White, Auteur ; M. D. Bolton, Auteur Année de publication : 2008 Article en page(s) : pp. 154–163 Note générale : Geotechnical and geoenvironmental engineeringa Langues : Anglais (eng) Mots-clés : Buried  pipes  Soil  deformation  Sand  Uplift  resistance  Particle  size  Imaging  techniques Résumé : Reliable design against upheaval buckling of offshore pipelines requires the uplift response to be predicted. This paper describes a model-scale investigation into the mechanisms by which uplift resistance is mobilized in silica sand, and illustrates how the observed mechanisms are captured in prediction models. A novel image-based deformation measurement technique has been used. The results show that peak uplift resistance is mobilized through the formation of an inverted trapezoidal block, bounded by a pair of distributed shear zones. The inclination of the shear zone is dependent on the soil density, and therefore dilatancy. After peak resistance, shear bands form and softening behavior is observed. At large pipe displacements, either a combination of a vertical sliding block mechanism and a flow-around mechanism near the pipe or a localized flow-around mechanism without surface heave is observed, depending on the soil density and particle size. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2815 [...] [article] Uplift mechanisms of pipes buried in sand [texte imprimé] / C. Y. Cheuk, Auteur ; D. J. White, Auteur ; M. D. Bolton, Auteur . - 2008 . - pp. 154–163. Geotechnical and geoenvironmental engineeringa Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 154–163 Mots-clés : Buried  pipes  Soil  deformation  Sand  Uplift  resistance  Particle  size  Imaging  techniques Résumé : Reliable design against upheaval buckling of offshore pipelines requires the uplift response to be predicted. This paper describes a model-scale investigation into the mechanisms by which uplift resistance is mobilized in silica sand, and illustrates how the observed mechanisms are captured in prediction models. A novel image-based deformation measurement technique has been used. The results show that peak uplift resistance is mobilized through the formation of an inverted trapezoidal block, bounded by a pair of distributed shear zones. The inclination of the shear zone is dependent on the soil density, and therefore dilatancy. After peak resistance, shear bands form and softening behavior is observed. At large pipe displacements, either a combination of a vertical sliding block mechanism and a flow-around mechanism near the pipe or a localized flow-around mechanism without surface heave is observed, depending on the soil density and particle size. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2815 [...]

Postshaking shear strain localization in a centrifuge model of a saturated sand slope / Erik J. Malvick in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 164–174 Titre : Postshaking shear strain localization in a centrifuge model of a saturated sand slope Type de document : texte imprimé Auteurs : Erik J. Malvick, Auteur ; Kutter, Bruce L., Auteur ; Ross W. Boulanger, Auteur Année de publication : 2008 Article en page(s) : pp. 164–174 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Slopes  Sand  Saturated  soils  Pore  water Résumé : This paper presents analyses of a test conducted on a 9-m-radius centrifuge to study the redistribution of pore water during diffusion of earthquake-induced excess pore pressures in a sand slope with embedded silt layers. The centrifuge model developed large postshaking deformations associated with shear strain localization at the interface between the sand and silt layers. Dense arrays of pore pressure transducers provided detailed measurements of pore pressure variations in time and space within the slope. A new data analysis approach is presented in which measured pore-pressures are used to compute flow rates and volumetric strains as a function of time and position throughout the slope. Hydraulic gradients were calculated by numerical differentiation of measured pore-pressure distributions with respect to position. Flow rates that were based on Darcy’s law were then integrated with respect to time to obtain flow quantities, from which volumetric strains were computed. A second data analysis approach that computes volumetric strains on the basis of soil compressibility and changes in pore pressure provided an independent computation of strains in consolidating zones. Results using these data analysis procedures confirm that a dilating (loosening) zone of significant thickness developed in the sand immediately beneath an embedded silt layer that had impeded the drainage of high pore pressures. These results support the hypothesis that the dilating zone corresponds to regions where the mobilized friction angle exceeds the critical state friction angle and that the dilating zone can be initially relatively thick before its size diminishes to the thickness of a thin shear band after the peak friction angle is mobilized. Quantification of the evolution of the size of the dilating zone is a key to understanding the magnitude of deformations associated with void redistribution. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2816 [...] [article] Postshaking shear strain localization in a centrifuge model of a saturated sand slope [texte imprimé] / Erik J. Malvick, Auteur ; Kutter, Bruce L., Auteur ; Ross W. Boulanger, Auteur . - 2008 . - pp. 164–174. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 164–174 Mots-clés : Slopes  Sand  Saturated  soils  Pore  water Résumé : This paper presents analyses of a test conducted on a 9-m-radius centrifuge to study the redistribution of pore water during diffusion of earthquake-induced excess pore pressures in a sand slope with embedded silt layers. The centrifuge model developed large postshaking deformations associated with shear strain localization at the interface between the sand and silt layers. Dense arrays of pore pressure transducers provided detailed measurements of pore pressure variations in time and space within the slope. A new data analysis approach is presented in which measured pore-pressures are used to compute flow rates and volumetric strains as a function of time and position throughout the slope. Hydraulic gradients were calculated by numerical differentiation of measured pore-pressure distributions with respect to position. Flow rates that were based on Darcy’s law were then integrated with respect to time to obtain flow quantities, from which volumetric strains were computed. A second data analysis approach that computes volumetric strains on the basis of soil compressibility and changes in pore pressure provided an independent computation of strains in consolidating zones. Results using these data analysis procedures confirm that a dilating (loosening) zone of significant thickness developed in the sand immediately beneath an embedded silt layer that had impeded the drainage of high pore pressures. These results support the hypothesis that the dilating zone corresponds to regions where the mobilized friction angle exceeds the critical state friction angle and that the dilating zone can be initially relatively thick before its size diminishes to the thickness of a thin shear band after the peak friction angle is mobilized. Quantification of the evolution of the size of the dilating zone is a key to understanding the magnitude of deformations associated with void redistribution. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2816 [...]

Probability of exceedance estimates for scour depth around bridge piers / Laura C. Bolduc in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 175–184 Titre : Probability of exceedance estimates for scour depth around bridge piers Type de document : texte imprimé Auteurs : Laura C. Bolduc, Auteur ; Gardoni, Paolo, Auteur ; Jean-Louis Briaud, Auteur Année de publication : 2008 Article en page(s) : pp. 175–184 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Bridges  Piers  Scour  Probability  Estimation Résumé : Scour at a bridge pier is the formation of a hole around the pier due to the erosion of soil by flowing water; this hole in the soil reduces the carrying capacity of the foundation and the pier. Excessive scour can cause a bridge pier to fail without warning. Current predictions of the depth of the scour hole around a bridge pier are based on deterministic models. This paper considers two alternative deterministic models to predict scour depth. For each deterministic model, a corresponding probabilistic model is constructed using a Bayesian statistical approach and available field and experimental data. The developed probabilistic models account for the estimated bias in the deterministic models and for the model uncertainty. Parameters from both prediction models are compared to determine their accuracy. The developed probabilistic models are used to estimate the probability of exceedance of scour depth around bridge piers. The method is demonstrated on an example bridge pier. The paper addresses model uncertainties for given hydrologic variables. Hydrologic uncertainties have been presented in a separate paper. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2817 [...] [article] Probability of exceedance estimates for scour depth around bridge piers [texte imprimé] / Laura C. Bolduc, Auteur ; Gardoni, Paolo, Auteur ; Jean-Louis Briaud, Auteur . - 2008 . - pp. 175–184. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 175–184 Mots-clés : Bridges  Piers  Scour  Probability  Estimation Résumé : Scour at a bridge pier is the formation of a hole around the pier due to the erosion of soil by flowing water; this hole in the soil reduces the carrying capacity of the foundation and the pier. Excessive scour can cause a bridge pier to fail without warning. Current predictions of the depth of the scour hole around a bridge pier are based on deterministic models. This paper considers two alternative deterministic models to predict scour depth. For each deterministic model, a corresponding probabilistic model is constructed using a Bayesian statistical approach and available field and experimental data. The developed probabilistic models account for the estimated bias in the deterministic models and for the model uncertainty. Parameters from both prediction models are compared to determine their accuracy. The developed probabilistic models are used to estimate the probability of exceedance of scour depth around bridge piers. The method is demonstrated on an example bridge pier. The paper addresses model uncertainties for given hydrologic variables. Hydrologic uncertainties have been presented in a separate paper. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2817 [...]

Simplified plane-strain modeling of stone-column reinforced ground / S. A. Tan in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 185–194 Titre : Simplified plane-strain modeling of stone-column reinforced ground Type de document : texte imprimé Auteurs : S. A. Tan, Auteur ; S. Tjahyono, Auteur ; K. K. Oo, Auteur Année de publication : 2008 Article en page(s) : pp. 185–194 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Plane  strain  Columns  Stones  Soil  consolidation  Numerical  models  Constitutive  models  Plastic  deformation  Embankments Résumé : The acceleration of consolidation rate by stone columns was mostly analyzed within the framework of a basic unit cell (i.e., a cylindrical soil body around a column). A method of converting the axisymmetric unit cell into the equivalent plane-strain model would be required for two-dimensional numerical modeling of multicolumn field applications. This paper proposes two simplified conversion methods to obtain the equivalent plane-strain model of the unit cell, and investigates their applicability to multicolumn reinforced ground. In the first conversion method, the soil permeability is matched according to an analytical equation, whereas in the second method, the column width is matched based on the equivalence of column area. The validity of these methods is tested by comparison with the numerical results of unit-cell simulations and with the field data from an embankment case history. The results show that for the case of linear-elastic material modeling, both methods produce reasonably accurate long-term consolidation settlements, whereas for the case of elastoplastic material modeling, the second method is preferable as the first one gives erroneously lower long-term settlements. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2818 [...] [article] Simplified plane-strain modeling of stone-column reinforced ground [texte imprimé] / S. A. Tan, Auteur ; S. Tjahyono, Auteur ; K. K. Oo, Auteur . - 2008 . - pp. 185–194. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 185–194 Mots-clés : Plane  strain  Columns  Stones  Soil  consolidation  Numerical  models  Constitutive  models  Plastic  deformation  Embankments Résumé : The acceleration of consolidation rate by stone columns was mostly analyzed within the framework of a basic unit cell (i.e., a cylindrical soil body around a column). A method of converting the axisymmetric unit cell into the equivalent plane-strain model would be required for two-dimensional numerical modeling of multicolumn field applications. This paper proposes two simplified conversion methods to obtain the equivalent plane-strain model of the unit cell, and investigates their applicability to multicolumn reinforced ground. In the first conversion method, the soil permeability is matched according to an analytical equation, whereas in the second method, the column width is matched based on the equivalence of column area. The validity of these methods is tested by comparison with the numerical results of unit-cell simulations and with the field data from an embankment case history. The results show that for the case of linear-elastic material modeling, both methods produce reasonably accurate long-term consolidation settlements, whereas for the case of elastoplastic material modeling, the second method is preferable as the first one gives erroneously lower long-term settlements. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2818 [...]

Mechanistic model for one-dimensional consolidation behavior of nonsegregating oil sands tailings / R. C. Wong in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 195–202 Titre : Mechanistic model for one-dimensional consolidation behavior of nonsegregating oil sands tailings Type de document : texte imprimé Auteurs : R. C. Wong, Auteur ; B. N. Mills, Auteur ; Y. B. Liu, Auteur Année de publication : 2008 Article en page(s) : pp. 195–202 Note générale : Geotechnical a,d geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  consolidation  Permeability  Compression  Mixtures  Tailings Résumé : Thermal-chemical-hydraulic separation process is used to extract bitumen from surface mined oil sands ores. Huge amounts of oil sands fine tailings are produced from the extraction process. The most fundamentally challenging issue facing the geo-environmental community is containment, long-term storage, and volume reduction of oil sands fine tailings. One of the fine tailings disposal techniques is to homogenize fine tailings with coarse tailings forming nonsegregating tailings (NST). NST exhibits enhanced performance in consolidation and strength, and reduction in water retention as compared to fine tailings. This paper examines one-dimensional consolidation behavior of NST with varying fine and coarse tailings compositions. A mechanistic model based on theory of mixture is developed and proposed to predict consolidation behavior of NST. This model is demonstrated to achieve an optimum design of NST for accelerated consolidation rate and water recovery. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2819 [...] [article] Mechanistic model for one-dimensional consolidation behavior of nonsegregating oil sands tailings [texte imprimé] / R. C. Wong, Auteur ; B. N. Mills, Auteur ; Y. B. Liu, Auteur . - 2008 . - pp. 195–202. Geotechnical a,d geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 195–202 Mots-clés : Soil  consolidation  Permeability  Compression  Mixtures  Tailings Résumé : Thermal-chemical-hydraulic separation process is used to extract bitumen from surface mined oil sands ores. Huge amounts of oil sands fine tailings are produced from the extraction process. The most fundamentally challenging issue facing the geo-environmental community is containment, long-term storage, and volume reduction of oil sands fine tailings. One of the fine tailings disposal techniques is to homogenize fine tailings with coarse tailings forming nonsegregating tailings (NST). NST exhibits enhanced performance in consolidation and strength, and reduction in water retention as compared to fine tailings. This paper examines one-dimensional consolidation behavior of NST with varying fine and coarse tailings compositions. A mechanistic model based on theory of mixture is developed and proposed to predict consolidation behavior of NST. This model is demonstrated to achieve an optimum design of NST for accelerated consolidation rate and water recovery. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2819 [...]

Durability of cement stabilized low plasticity soils / Zhongjie Zhang in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 203–213 Titre : Durability of cement stabilized low plasticity soils Type de document : texte imprimé Auteurs : Zhongjie Zhang, Auteur ; Mingjiang Tao, Auteur Année de publication : 2008 Article en page(s) : pp. 203–213 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Cements  Stabilization  Durability  Plasticity  Compressive  strength Résumé : Three testing methods for predicting the durability of cement-stabilized soils—the tube suction (TS), 7-day unconfined compression strength (UCS), and wetting–drying durability tests—were tested and compared for their correlations and influence factors using a problematic low plastic silt clay from subgrade commonly encountered in Louisiana. A series of samples was molded at six different cement dosages (2.5, 4.5, 6.5, 8.5, 10.5, and 12.5% by dry weight of the soil) and four different molding moisture contents (15.5, 18.5, 21.5, and 24.5%). The test results indicate that the water–cement ratio of cement-stabilized soil had the dominant influence on the maximum dielectric value (DV), 7-day UCS, and durability of stabilized samples tested, although the dry unit weight of cement-stabilized soil could cause the variation of the results. This study confirms that TS, 7-day UCS, and wetting-drying durability tests are equivalent in predicting durability, and tentative charts to ensuring the durability of cement-stabilized low plasticity soils are developed using their 7-day UCS or the maximum DV values. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2820 [...] [article] Durability of cement stabilized low plasticity soils [texte imprimé] / Zhongjie Zhang, Auteur ; Mingjiang Tao, Auteur . - 2008 . - pp. 203–213. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 203–213 Mots-clés : Cements  Stabilization  Durability  Plasticity  Compressive  strength Résumé : Three testing methods for predicting the durability of cement-stabilized soils—the tube suction (TS), 7-day unconfined compression strength (UCS), and wetting–drying durability tests—were tested and compared for their correlations and influence factors using a problematic low plastic silt clay from subgrade commonly encountered in Louisiana. A series of samples was molded at six different cement dosages (2.5, 4.5, 6.5, 8.5, 10.5, and 12.5% by dry weight of the soil) and four different molding moisture contents (15.5, 18.5, 21.5, and 24.5%). The test results indicate that the water–cement ratio of cement-stabilized soil had the dominant influence on the maximum dielectric value (DV), 7-day UCS, and durability of stabilized samples tested, although the dry unit weight of cement-stabilized soil could cause the variation of the results. This study confirms that TS, 7-day UCS, and wetting-drying durability tests are equivalent in predicting durability, and tentative charts to ensuring the durability of cement-stabilized low plasticity soils are developed using their 7-day UCS or the maximum DV values. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2820 [...]

Numerical modeling of contaminant transport through soils / A. A. Javadi in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 214–230 Titre : Numerical modeling of contaminant transport through soils : case study Type de document : texte imprimé Auteurs : A. A. Javadi, Auteur ; M. M. Al-Najjar, Auteur ; B. Evans, Auteur Année de publication : 2008 Article en page(s) : pp. 214–230 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Pollutants  Unsaturated  soils  Finite  element  method  Case  reports  Finite  element  method  Advection  Dispersion  Diffusion  Adsorption Résumé : This paper presents the development and validation of a numerical model for simulation of the flow of water and air and contaminant transport through unsaturated soils. The governing differential equations include two mass balance equations for the water phase and air phase together with a balance equation for contaminant transport through the two phases. In the model the nonlinear system of the governing differential equations was solved using a finite-element method in the space domain and a finite difference scheme in the time domain. The governing equation of the miscible contaminant transport including advection, dispersion-diffusion and adsorption effects are presented. The mathematical framework and the numerical implementation of the model are described in detail. The model is validated by application to standard experiments on contaminant transport in unsaturated soils. The application of the model to a case study is then presented and discussed. Finally, the merits and limitations of the model are highlighted. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2821 [...] [article] Numerical modeling of contaminant transport through soils : case study [texte imprimé] / A. A. Javadi, Auteur ; M. M. Al-Najjar, Auteur ; B. Evans, Auteur . - 2008 . - pp. 214–230. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 214–230 Mots-clés : Pollutants  Unsaturated  soils  Finite  element  method  Case  reports  Finite  element  method  Advection  Dispersion  Diffusion  Adsorption Résumé : This paper presents the development and validation of a numerical model for simulation of the flow of water and air and contaminant transport through unsaturated soils. The governing differential equations include two mass balance equations for the water phase and air phase together with a balance equation for contaminant transport through the two phases. In the model the nonlinear system of the governing differential equations was solved using a finite-element method in the space domain and a finite difference scheme in the time domain. The governing equation of the miscible contaminant transport including advection, dispersion-diffusion and adsorption effects are presented. The mathematical framework and the numerical implementation of the model are described in detail. The model is validated by application to standard experiments on contaminant transport in unsaturated soils. The application of the model to a case study is then presented and discussed. Finally, the merits and limitations of the model are highlighted. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2821 [...]

Water drainage in double-porosity soils / Jolanta Lewandowska in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 231–243 Titre : Water drainage in double-porosity soils : experiments and micro–macro modeling Type de document : texte imprimé Auteurs : Jolanta Lewandowska, Auteur ; Tien Dung Tran Ngoc, Auteur ; Michel Vauclin, Auteur Année de publication : 2008 Article en page(s) : pp. 231–243 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Unsaturated  soils  Nonuniform  flow  Drainage  Microstructure  Heterogeneity  Scale  effect  Gamma  rays  Model  verification  Porous  media Résumé : This paper presents the experimental validation of a macroscopic model of unsaturated flow in double-porosity soils, which was developed using the asymptotic homogenization method. The model was implemented into a code which enables micro–macro coupled calculations of macroscopically one-dimensional and microscopically three-dimensional problems. A series of drainage experiments were carried out in a column filled with a double porosity medium. The porous medium is composed of Hostun sand and porous spheres made of sintered clay, periodically distributed in the sand. The characteristic pores sizes of the two media differ by two orders of magnitude. During the experiments the water content evolution inside the column, the capillary pressure, and the flux at the bottom of the column were measured. The numerical simulations results showed a good agreement with the experimental data, confirming the predictive ability of the model. The experimental and numerical evidence of the influence of the microporous inclusions on the flow dynamics (flux retardation, water retention in the microporosity), is clearly shown. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2823 [...] [article] Water drainage in double-porosity soils : experiments and micro–macro modeling [texte imprimé] / Jolanta Lewandowska, Auteur ; Tien Dung Tran Ngoc, Auteur ; Michel Vauclin, Auteur . - 2008 . - pp. 231–243. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 231–243 Mots-clés : Unsaturated  soils  Nonuniform  flow  Drainage  Microstructure  Heterogeneity  Scale  effect  Gamma  rays  Model  verification  Porous  media Résumé : This paper presents the experimental validation of a macroscopic model of unsaturated flow in double-porosity soils, which was developed using the asymptotic homogenization method. The model was implemented into a code which enables micro–macro coupled calculations of macroscopically one-dimensional and microscopically three-dimensional problems. A series of drainage experiments were carried out in a column filled with a double porosity medium. The porous medium is composed of Hostun sand and porous spheres made of sintered clay, periodically distributed in the sand. The characteristic pores sizes of the two media differ by two orders of magnitude. During the experiments the water content evolution inside the column, the capillary pressure, and the flux at the bottom of the column were measured. The numerical simulations results showed a good agreement with the experimental data, confirming the predictive ability of the model. The experimental and numerical evidence of the influence of the microporous inclusions on the flow dynamics (flux retardation, water retention in the microporosity), is clearly shown. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2823 [...]

Determination of the critical slip surface using artificial fish swarms algorithm / Y. M. Cheng in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 244–251 Titre : Determination of the critical slip surface using artificial fish swarms algorithm Type de document : texte imprimé Auteurs : Y. M. Cheng, Auteur ; Liang, L., Auteur ; S. C. Chi, Auteur Année de publication : 2008 Article en page(s) : pp. 244–251 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Slope  stability  Algorithms  Optimization  Finite  element  method  Slip Résumé : The writers have come across a difficult stability analysis problem where there are several “strong” local minima. Several well known heuristic global minimum methods fail to locate the global minimum for this case, and the writers finally adopt the artificial fish swarms algorithm to overcome this difficult problem. This optimization algorithm is demonstrated to be effective and efficient for normal problems. To illustrate the effectiveness of the proposed algorithm, three difficult examples are considered. The sensitivity of the proposed algorithm with respect to the parameters used for the global optimization algorithm will also be investigated in this paper. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2824 [...] [article] Determination of the critical slip surface using artificial fish swarms algorithm [texte imprimé] / Y. M. Cheng, Auteur ; Liang, L., Auteur ; S. C. Chi, Auteur . - 2008 . - pp. 244–251. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 244–251 Mots-clés : Slope  stability  Algorithms  Optimization  Finite  element  method  Slip Résumé : The writers have come across a difficult stability analysis problem where there are several “strong” local minima. Several well known heuristic global minimum methods fail to locate the global minimum for this case, and the writers finally adopt the artificial fish swarms algorithm to overcome this difficult problem. This optimization algorithm is demonstrated to be effective and efficient for normal problems. To illustrate the effectiveness of the proposed algorithm, three difficult examples are considered. The sensitivity of the proposed algorithm with respect to the parameters used for the global optimization algorithm will also be investigated in this paper. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2824 [...]

Search for critical slip surface in slope stability analysis by spline-based GA method / Jianping Sun in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 252–256 Titre : Search for critical slip surface in slope stability analysis by spline-based GA method Type de document : texte imprimé Auteurs : Jianping Sun, Auteur ; Jiachun Li, Auteur ; Qingquan Liu, Auteur Année de publication : 2008 Article en page(s) : pp. 252–256 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Slope  stability  Safety  Algorithms  Limit  equilibrium Résumé : The stability of a soil slope is usually analyzed by limit equilibrium methods, in which the identification of the critical slip surface is of principal importance. In this study the spline curve in conjunction with a genetic algorithm is used to search the critical slip surface, and Spencer’s method is employed to calculate the factor of safety. Three examples are presented to illustrate the reliability and efficiency of the method. Slip surfaces defined by a series of straight lines are compared with those defined by spline curves, and the results indicate that use of spline curves renders better results for a given number of slip surface nodal points comparing with the approximation using straight line segments. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2825 [...] [article] Search for critical slip surface in slope stability analysis by spline-based GA method [texte imprimé] / Jianping Sun, Auteur ; Jiachun Li, Auteur ; Qingquan Liu, Auteur . - 2008 . - pp. 252–256. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 252–256 Mots-clés : Slope  stability  Safety  Algorithms  Limit  equilibrium Résumé : The stability of a soil slope is usually analyzed by limit equilibrium methods, in which the identification of the critical slip surface is of principal importance. In this study the spline curve in conjunction with a genetic algorithm is used to search the critical slip surface, and Spencer’s method is employed to calculate the factor of safety. Three examples are presented to illustrate the reliability and efficiency of the method. Slip surfaces defined by a series of straight lines are compared with those defined by spline curves, and the results indicate that use of spline curves renders better results for a given number of slip surface nodal points comparing with the approximation using straight line segments. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2825 [...]

Reinforced concrete walls with vulnerable foundations / J. Paul Smith-Pardo in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°2 (Fevrier 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 257–261 Titre : Reinforced concrete walls with vulnerable foundations Type de document : texte imprimé Auteurs : J. Paul Smith-Pardo, Auteur Année de publication : 2008 Article en page(s) : pp. 257–261 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  structure  Interactions  Shallow  foundation  Limit  analysis  Concrete  Reinforced  concrete  Walls Résumé : Moment capacities of shallow foundations are compared with those of reinforced concrete walls in order to determine the likelihood of exceeding the bearing capacity of the supporting soil in buildings subjected to strong ground motions. Recommendations are made regarding the appropriate modeling at the base of first-story walls in compliance with the moment-capacity axial load interaction of the supporting foundations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2825 [...] [article] Reinforced concrete walls with vulnerable foundations [texte imprimé] / J. Paul Smith-Pardo, Auteur . - 2008 . - pp. 257–261. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°2 (Fevrier 2008) . - pp. 257–261 Mots-clés : Soil  structure  Interactions  Shallow  foundation  Limit  analysis  Concrete  Reinforced  concrete  Walls Résumé : Moment capacities of shallow foundations are compared with those of reinforced concrete walls in order to determine the likelihood of exceeding the bearing capacity of the supporting soil in buildings subjected to strong ground motions. Recommendations are made regarding the appropriate modeling at the base of first-story walls in compliance with the moment-capacity axial load interaction of the supporting foundations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A2%2825 [...]

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