Documents disponibles écrits par cet auteur

Effect of progressive failure on measured shear strength of geomembrane/GCL interface / Fox, Patrick J. in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°4 (Avril 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°4 (Avril 2008) . - pp. 459–469 Titre : Effect of progressive failure on measured shear strength of geomembrane/GCL interface Type de document : texte imprimé Auteurs : Fox, Patrick J., Auteur ; Robert H. Kim, Auteur Année de publication : 2008 Article en page(s) : pp. 459–469 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Shear  strength  Geosynthetics  Progressive  failure  Numerical  analysis Résumé : This paper presents experimental data and numerical modeling results that illustrate the effects of progressive failure on the measured shear strength of a textured geomembrane/geosynthetic clay liner (GMX/GCL) interface. Large direct shear tests were conducted using different specimen gripping/clamping systems to isolate the effects of progressive failure. These tests indicate that progressive failure causes a reduction in measured peak shear strength, an increase in the displacement at peak, an increase in large displacement shear strength, and significant distortion of the shear stress–displacement relationship. A numerical model was developed to simulate progressive failure of a GMX/GCL interface. Measured and simulated shear stress–displacement relationships are in good-to-excellent agreement at four normal stress levels. The model was then used to investigate mechanisms of progressive interface failure and factors that control its significance. The results indicate that accurate measurements of shear stress–displacement behavior and strength are obtained when gripping surfaces prevent slippage of the test specimen and the intended failure surface has the lowest shear resistance of all possible sliding surfaces. The use of proper gripping surfaces is expected to reduce difficulties in test data interpretation and to increase the accuracy and reproducibility of test results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A4%2845 [...] [article] Effect of progressive failure on measured shear strength of geomembrane/GCL interface [texte imprimé] / Fox, Patrick J., Auteur ; Robert H. Kim, Auteur . - 2008 . - pp. 459–469. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°4 (Avril 2008) . - pp. 459–469 Mots-clés : Shear  strength  Geosynthetics  Progressive  failure  Numerical  analysis Résumé : This paper presents experimental data and numerical modeling results that illustrate the effects of progressive failure on the measured shear strength of a textured geomembrane/geosynthetic clay liner (GMX/GCL) interface. Large direct shear tests were conducted using different specimen gripping/clamping systems to isolate the effects of progressive failure. These tests indicate that progressive failure causes a reduction in measured peak shear strength, an increase in the displacement at peak, an increase in large displacement shear strength, and significant distortion of the shear stress–displacement relationship. A numerical model was developed to simulate progressive failure of a GMX/GCL interface. Measured and simulated shear stress–displacement relationships are in good-to-excellent agreement at four normal stress levels. The model was then used to investigate mechanisms of progressive interface failure and factors that control its significance. The results indicate that accurate measurements of shear stress–displacement behavior and strength are obtained when gripping surfaces prevent slippage of the test specimen and the intended failure surface has the lowest shear resistance of all possible sliding surfaces. The use of proper gripping surfaces is expected to reduce difficulties in test data interpretation and to increase the accuracy and reproducibility of test results. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A4%2845 [...]

Effective soil density for propagation of small strain shear waves in saturated soil / Tong Qiu in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°12 (Décembre 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°12 (Décembre 2008) . - pp. 1815–1819 Titre : Effective soil density for propagation of small strain shear waves in saturated soil Type de document : texte imprimé Auteurs : Tong Qiu, Auteur ; Fox, Patrick J., Auteur Année de publication : 2009 Article en page(s) : pp. 1815–1819 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  properties  Density  Saturated  soils  Shear  modulus  Wave  velocity  Hydraulic  conductivity  Wave  propagation Résumé : This technical note defines an “effective soil density” that controls the velocity of small strain shear waves in saturated soil. Biot theory indicates that the ratio of effective density to saturated density will generally range from 0.75 to 1.0 and is a function of specific gravity of solids, porosity, hydraulic conductivity, and shear wave frequency. For many geotechnical applications, effective density will be equal to saturated density for low hydraulic conductivity soils (clays and silts) and may be less than saturated density for high hydraulic conductivity soils (clean sands and gravels). The findings are relevant to applications involving the propagation of small strain shear waves through saturated soil, and in particular for laboratory and field tests in which shear modulus is back-calculated from measured shear-wave velocity. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A12%281 [...] [article] Effective soil density for propagation of small strain shear waves in saturated soil [texte imprimé] / Tong Qiu, Auteur ; Fox, Patrick J., Auteur . - 2009 . - pp. 1815–1819. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°12 (Décembre 2008) . - pp. 1815–1819 Mots-clés : Soil  properties  Density  Saturated  soils  Shear  modulus  Wave  velocity  Hydraulic  conductivity  Wave  propagation Résumé : This technical note defines an “effective soil density” that controls the velocity of small strain shear waves in saturated soil. Biot theory indicates that the ratio of effective density to saturated density will generally range from 0.75 to 1.0 and is a function of specific gravity of solids, porosity, hydraulic conductivity, and shear wave frequency. For many geotechnical applications, effective density will be equal to saturated density for low hydraulic conductivity soils (clays and silts) and may be less than saturated density for high hydraulic conductivity soils (clean sands and gravels). The findings are relevant to applications involving the propagation of small strain shear waves through saturated soil, and in particular for laboratory and field tests in which shear modulus is back-calculated from measured shear-wave velocity. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A12%281 [...]

Hydraulic Damping of Saturated Poroelestic Soils During Steady-State-State Vibration / Tong Qiu in Journal of engineering mechanics, V ol. 132 N°8 (Août 2006) 

Public ISBD [article]  in Journal of engineering mechanics > V ol. 132 N°8 (Août 2006) . - 859-870 p. Titre : Hydraulic Damping of Saturated Poroelestic Soils During Steady-State-State Vibration Titre original : Atténuation Hydraulique des Sols saturés de Poro-elesticue Pendant la Vibration d'Etat d'Equilibre Type de document : texte imprimé Auteurs : Tong Qiu, Auteur ; Abousleiman, Younane, Editeur scientifique ; Fox, Patrick J., Auteur Article en page(s) : 859-870 p. Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Porous  media  Saturated  soils  Damping  Coupling  Soil  dynamics  Vibration  Poro-elasticity  Médias  poreux  Sols  saturés  Atténuation  Accouplement  Dynamique  de  sol  Poro-élasticité Index. décimale : 621.3 Ingénierie électrique Résumé : A theoretical study of the steady-state response of a saturated poroelastic soil column during compressional and rotational harmonic vibrations is presented. Hydraulic damping due to Biot flow is evaluated for top-drained and double-drained boundary conditions and for compressional and rotational motions using the theory of a damped single-degree-of-freedom system. For compressional motions, the dynamic response of gravels and sands is highly influenced by the compressibility of the pore fluid. More hydraulic damping occurs as soil hydraulic conductivity increases and as the column boundary conditions change from top drained to double drained. On the other hand, hydraulic damping for rotational motions is significantly less than that for compressional motions and is dependent on a dimensionless hydraulic conductivity parameter Ks. For Ks within the range of 10-3-100, hydraulic damping may have an important contribution to total soil damping, especially at small strain levels. Une étude théorique de la réponse d'état d'équilibre d'une colonne poroelastic saturée de sol pendant des vibrations harmoniques de compression et de rotation est présentée. L'atténuation hydraulique due à l'écoulement de Biot est évaluée pour des états vidangés vidangés et doubles de dessus de frontière et pour des mouvements de compression et de rotation en utilisant la théorie d'un seul degré atténué de système de liberté. Pour des mouvements de compression, la réponse dynamique des graviers et des sables est fortement influencée par la compressibilité du fluide de pore. Une atténuation plus hydraulique se produit pendant que des augmentations hydrauliques de conductivité de sol et pendant que les conditions de frontière de colonne changent du dessus vidangé en le double vidangé. D'autre part, l'atténuation hydraulique pour des mouvements de rotation est de manière significative moins que cela pour des mouvements de compression et dépend d'un paramètre hydraulique sans dimensions K?s de conductivité ?. Pour K?s ? dans la marge de 10?-3?-100, l'atténuation hydraulique peut avoir une contribution importante pour se monter au sol atténuant, particulièrement à la petite contrainte nivelle. En ligne : qiutong@ucla.edu, fox.407@osu.edu [article] Hydraulic Damping of Saturated Poroelestic Soils During Steady-State-State Vibration = Atténuation Hydraulique des Sols saturés de Poro-elesticue Pendant la Vibration d'Etat d'Equilibre [texte imprimé] / Tong Qiu, Auteur ; Abousleiman, Younane, Editeur scientifique ; Fox, Patrick J., Auteur . - 859-870 p. Génie Mécanique Langues : Anglais (eng) in Journal of engineering mechanics > V ol. 132 N°8 (Août 2006) . - 859-870 p. Mots-clés : Porous  media  Saturated  soils  Damping  Coupling  Soil  dynamics  Vibration  Poro-elasticity  Médias  poreux  Sols  saturés  Atténuation  Accouplement  Dynamique  de  sol  Poro-élasticité Index. décimale : 621.3 Ingénierie électrique Résumé : A theoretical study of the steady-state response of a saturated poroelastic soil column during compressional and rotational harmonic vibrations is presented. Hydraulic damping due to Biot flow is evaluated for top-drained and double-drained boundary conditions and for compressional and rotational motions using the theory of a damped single-degree-of-freedom system. For compressional motions, the dynamic response of gravels and sands is highly influenced by the compressibility of the pore fluid. More hydraulic damping occurs as soil hydraulic conductivity increases and as the column boundary conditions change from top drained to double drained. On the other hand, hydraulic damping for rotational motions is significantly less than that for compressional motions and is dependent on a dimensionless hydraulic conductivity parameter Ks. For Ks within the range of 10-3-100, hydraulic damping may have an important contribution to total soil damping, especially at small strain levels. Une étude théorique de la réponse d'état d'équilibre d'une colonne poroelastic saturée de sol pendant des vibrations harmoniques de compression et de rotation est présentée. L'atténuation hydraulique due à l'écoulement de Biot est évaluée pour des états vidangés vidangés et doubles de dessus de frontière et pour des mouvements de compression et de rotation en utilisant la théorie d'un seul degré atténué de système de liberté. Pour des mouvements de compression, la réponse dynamique des graviers et des sables est fortement influencée par la compressibilité du fluide de pore. Une atténuation plus hydraulique se produit pendant que des augmentations hydrauliques de conductivité de sol et pendant que les conditions de frontière de colonne changent du dessus vidangé en le double vidangé. D'autre part, l'atténuation hydraulique pour des mouvements de rotation est de manière significative moins que cela pour des mouvements de compression et dépend d'un paramètre hydraulique sans dimensions K?s de conductivité ?. Pour K?s ? dans la marge de 10?-3?-100, l'atténuation hydraulique peut avoir une contribution importante pour se monter au sol atténuant, particulièrement à la petite contrainte nivelle. En ligne : qiutong@ucla.edu, fox.407@osu.edu

Investigation of consolidation-induced solute transport. I: effect of consolidation on transport parameters / Jangguen Lee in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 9 (Septembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 9 (Septembre 2009) . - pp. 1228–1238 Titre : Investigation of consolidation-induced solute transport. I: effect of consolidation on transport parameters Type de document : texte imprimé Auteurs : Jangguen Lee, Auteur ; Fox, Patrick J., Auteur ; John J. Lenhart, Auteur Année de publication : 2009 Article en page(s) : pp. 1228–1238 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  consolidationParametersSolutesSorptionInorganic  chemicals Résumé : This paper presents an experimental investigation of the effect of clay consolidation on parameters that govern the advective-dispersive transport of an inorganic solute. Batch, diffusion, dispersion, and solute transport tests were conducted using kaolinite clay and dilute solutions of potassium bromide (KBr). Batch tests produced the highest levels of K+ sorption and indicated that equilibrium sorption was achieved in approximately 10–30 min. The increase in sorption observed in the batch tests, as compared to the dispersion or solute transport tests, reflects the significantly lower solids-to-solution ratio and more efficient mixing process. By comparison, kaolinite consolidation had little effect on sorption due to the relatively small change in porosity. Values of hydrodynamic dispersion coefficient (Dh) , effective diffusion coefficient (D∗) , and apparent tortuosity factor decreased with decreasing porosity. Values of D∗ obtained for Br− were generally larger than for K+ , whereas Dh values for Br− were significantly smaller than for K+ . Values of longitudinal dispersivity (α) were larger for K+ than Br− and showed no clear trend with decreasing void ratio. In general, the experimental results suggest that changes in D∗ and Dh should be taken into account during clay consolidation whereas the sorption isotherm and α may be considered as unchanged during the consolidation process. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000047 [article] Investigation of consolidation-induced solute transport. I: effect of consolidation on transport parameters [texte imprimé] / Jangguen Lee, Auteur ; Fox, Patrick J., Auteur ; John J. Lenhart, Auteur . - 2009 . - pp. 1228–1238. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 9 (Septembre 2009) . - pp. 1228–1238 Mots-clés : Soil  consolidationParametersSolutesSorptionInorganic  chemicals Résumé : This paper presents an experimental investigation of the effect of clay consolidation on parameters that govern the advective-dispersive transport of an inorganic solute. Batch, diffusion, dispersion, and solute transport tests were conducted using kaolinite clay and dilute solutions of potassium bromide (KBr). Batch tests produced the highest levels of K+ sorption and indicated that equilibrium sorption was achieved in approximately 10–30 min. The increase in sorption observed in the batch tests, as compared to the dispersion or solute transport tests, reflects the significantly lower solids-to-solution ratio and more efficient mixing process. By comparison, kaolinite consolidation had little effect on sorption due to the relatively small change in porosity. Values of hydrodynamic dispersion coefficient (Dh) , effective diffusion coefficient (D∗) , and apparent tortuosity factor decreased with decreasing porosity. Values of D∗ obtained for Br− were generally larger than for K+ , whereas Dh values for Br− were significantly smaller than for K+ . Values of longitudinal dispersivity (α) were larger for K+ than Br− and showed no clear trend with decreasing void ratio. In general, the experimental results suggest that changes in D∗ and Dh should be taken into account during clay consolidation whereas the sorption isotherm and α may be considered as unchanged during the consolidation process. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000047

Investigation of Consolidation-Induced Solute Transport. II: Experimental and Numerical Results / Jangguen Lee in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 9 (Septembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 9 (Septembre 2009) . - pp. 1239–1253 Titre : Investigation of Consolidation-Induced Solute Transport. II: Experimental and Numerical Results Type de document : texte imprimé Auteurs : Jangguen Lee, Auteur ; Fox, Patrick J., Auteur Année de publication : 2009 Article en page(s) : pp. 1239–1253 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Soil  consolidationSolutesDispersionSorptionNumerical  modelsClays Résumé : This paper presents an experimental and numerical investigation of consolidation-induced solute transport. Diffusion and large strain consolidation tests were performed on composite specimens of kaolinite clay consisting of an upper uncontaminated layer and a lower layer contaminated with potassium bromide. Experimental measurements of effluent concentration, solute mass outflow, and final concentration profiles were obtained for a variety of initial, boundary, and loading conditions, including unload/reload. Numerical simulations were conducted using a computational model in which solute transport occurs by advection, dispersion, and sorption and is consistent with temporal and spatial variations of porosity and seepage velocity in the consolidating layer. Large strains were taken into account as well as variation of effective diffusion coefficient with porosity and nonlinear nonequilibrium sorption effects. The numerical simulations are in good to excellent agreement with the experimental measurements. Results indicate that, depending on conditions, diffusion and consolidation-induced advection can make important contributions to solute transport and mass outflow. Thus, both mechanisms should be considered for transport analyses involving soft contaminated clays undergoing large volume change. Results also indicate that nonequilibrium sorption effects were not significant for the materials and test conditions used in this study. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000048 [article] Investigation of Consolidation-Induced Solute Transport. II: Experimental and Numerical Results [texte imprimé] / Jangguen Lee, Auteur ; Fox, Patrick J., Auteur . - 2009 . - pp. 1239–1253. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 9 (Septembre 2009) . - pp. 1239–1253 Mots-clés : Soil  consolidationSolutesDispersionSorptionNumerical  modelsClays Résumé : This paper presents an experimental and numerical investigation of consolidation-induced solute transport. Diffusion and large strain consolidation tests were performed on composite specimens of kaolinite clay consisting of an upper uncontaminated layer and a lower layer contaminated with potassium bromide. Experimental measurements of effluent concentration, solute mass outflow, and final concentration profiles were obtained for a variety of initial, boundary, and loading conditions, including unload/reload. Numerical simulations were conducted using a computational model in which solute transport occurs by advection, dispersion, and sorption and is consistent with temporal and spatial variations of porosity and seepage velocity in the consolidating layer. Large strains were taken into account as well as variation of effective diffusion coefficient with porosity and nonlinear nonequilibrium sorption effects. The numerical simulations are in good to excellent agreement with the experimental measurements. Results indicate that, depending on conditions, diffusion and consolidation-induced advection can make important contributions to solute transport and mass outflow. Thus, both mechanisms should be considered for transport analyses involving soft contaminated clays undergoing large volume change. Results also indicate that nonequilibrium sorption effects were not significant for the materials and test conditions used in this study. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000048

Relationship between NP GCL internal and HDPE GMX/NP GCL interface shear strengths / Fox, Patrick J. in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 8 (Août 2011) 

Permalink