Documents disponibles écrits par cet auteur

Analysis of a large database of GCL-geomembrane interface shear strength results / John S. McCartney in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N°2 (Février 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°2 (Février 2009) . - pp. 209–223 Titre : Analysis of a large database of GCL-geomembrane interface shear strength results Type de document : texte imprimé Auteurs : John S. McCartney, Auteur ; Jorge G. Zornberg, Auteur ; Robert H. Swan Jr., Auteur Année de publication : 2009 Article en page(s) : pp. 209–223 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Database  Geomembranes  Shear  strength  Clay  liners Résumé : A database of 534 large-scale direct shear test results was assembled in this study to evaluate the interface shear strength between geosynthetic clay liners (GCLs) and geomembranes (GMs). The tests were conducted between 1992 and 2003 by a single independent laboratory using procedures consistent with current testing standards. The number of results in the database allowed quantification of the impact of GCL type, GM type, normal stress, and procedures for specimen hydration and consolidation on the shear strength of GCL-GM interfaces, as well as identification of sources of shear strength variability. The interface shear strength was found to be sensitive to the type of GCL internal reinforcement, GM polymer, and GM texturing, but not to the GM thickness or manufacturer. On average, the GCL internal shear strength was observed to be higher than the GCL-GM interface shear strength when tested using the same procedures. GCLs sheared internally show similar stress-displacement responses and friction angles to GCL-GM interfaces that incorporate a GCL with the same reinforcement type. Hydration under normal stresses below those used during shearing (followed by a consolidation period) led to higher GCL internal shear strength, but lower GCL-GM interface shear strength, than when hydration was conducted under the shearing normal stress. Such different responses are attributed to bentonite extrusion from the GCL into the interface. Good repeatability of test results was obtained using GCL and GM specimens from the same manufacturing lot, while high variability was obtained using specimens from different lots. GCL-GM interface peak shear strength variability was found to increase linearly with normal stress. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A2%2820 [...] [article] Analysis of a large database of GCL-geomembrane interface shear strength results [texte imprimé] / John S. McCartney, Auteur ; Jorge G. Zornberg, Auteur ; Robert H. Swan Jr., Auteur . - 2009 . - pp. 209–223. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°2 (Février 2009) . - pp. 209–223 Mots-clés : Database  Geomembranes  Shear  strength  Clay  liners Résumé : A database of 534 large-scale direct shear test results was assembled in this study to evaluate the interface shear strength between geosynthetic clay liners (GCLs) and geomembranes (GMs). The tests were conducted between 1992 and 2003 by a single independent laboratory using procedures consistent with current testing standards. The number of results in the database allowed quantification of the impact of GCL type, GM type, normal stress, and procedures for specimen hydration and consolidation on the shear strength of GCL-GM interfaces, as well as identification of sources of shear strength variability. The interface shear strength was found to be sensitive to the type of GCL internal reinforcement, GM polymer, and GM texturing, but not to the GM thickness or manufacturer. On average, the GCL internal shear strength was observed to be higher than the GCL-GM interface shear strength when tested using the same procedures. GCLs sheared internally show similar stress-displacement responses and friction angles to GCL-GM interfaces that incorporate a GCL with the same reinforcement type. Hydration under normal stresses below those used during shearing (followed by a consolidation period) led to higher GCL internal shear strength, but lower GCL-GM interface shear strength, than when hydration was conducted under the shearing normal stress. Such different responses are attributed to bentonite extrusion from the GCL into the interface. Good repeatability of test results was obtained using GCL and GM specimens from the same manufacturing lot, while high variability was obtained using specimens from different lots. GCL-GM interface peak shear strength variability was found to increase linearly with normal stress. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A2%2820 [...]

Analysis of thermo-active foundations with u-tube heat exchangers / Khaled Rouissi in Transactions of the ASME. Journal of solar energy engineering, Vol. 134 N° 2 (Mai 2012) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 134 N° 2 (Mai 2012) . - 08 p. Titre : Analysis of thermo-active foundations with u-tube heat exchangers Type de document : texte imprimé Auteurs : Khaled Rouissi, Auteur ; Moncef Krarti, Auteur ; John S. McCartney, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : solar energy Langues : Anglais (eng) Mots-clés : thermo-active  foundations;  ground  source  heat  pumps  (GSHPs);  U-tube;  finite  difference  method Index. décimale : 621.47 Résumé : This paper presents a heat transfer model for thermo-active drilled-shaft foundations used for heating and cooling buildings. Specifically, this paper presents a numerical approach to evaluate the unsteady temperature distribution within the ground medium surrounding the foundation as well as indoor/outdoor heat fluxes. In particular, a 2D numerical solution was obtained using the finite difference technique with a purely implicit solution scheme. The results of the sensitivity analysis indicate that the efficiency of the thermo-active foundation can be significantly improved with a proper selection of design parameters including heat exchanger fluid flow velocity, foundation depth, and foundation materials. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000134000002 [...] [article] Analysis of thermo-active foundations with u-tube heat exchangers [texte imprimé] / Khaled Rouissi, Auteur ; Moncef Krarti, Auteur ; John S. McCartney, Auteur . - 2012 . - 08 p. solar energy Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 134 N° 2 (Mai 2012) . - 08 p. Mots-clés : thermo-active  foundations;  ground  source  heat  pumps  (GSHPs);  U-tube;  finite  difference  method Index. décimale : 621.47 Résumé : This paper presents a heat transfer model for thermo-active drilled-shaft foundations used for heating and cooling buildings. Specifically, this paper presents a numerical approach to evaluate the unsteady temperature distribution within the ground medium surrounding the foundation as well as indoor/outdoor heat fluxes. In particular, a 2D numerical solution was obtained using the finite difference technique with a purely implicit solution scheme. The results of the sensitivity analysis indicate that the efficiency of the thermo-active foundation can be significantly improved with a proper selection of design parameters including heat exchanger fluid flow velocity, foundation depth, and foundation materials. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000134000002 [...]

Centrifuge permeameter for unsaturated soils. I, Theoretical basis and experimental developments / Jorge G. Zornberg in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 8 (Août 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1051-1063 Titre : Centrifuge permeameter for unsaturated soils. I, Theoretical basis and experimental developments Type de document : texte imprimé Auteurs : Jorge G. Zornberg, Auteur ; John S. McCartney, Auteur Année de publication : 2010 Article en page(s) : pp. 1051-1063 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Unsaturated  soils  Centrifuge  permeameter  Hydraulic  conductivity  function  Soil  water  retention  curve  TDR  Tensiometers Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A new centrifuge permeameter was developed with the specific objective of expediting the measurement of the hydraulic characteristics of unsaturated soils. The development, theoretical basis, and typical results associated with using the centrifuge permeameter for concurrent determination of the soil-water retention curve (SWRC) and hydraulic conductivity function (K function) of unsaturated soils are presented in this paper. Components developed for the centrifuge permeameter are described, including the centrifuge, permeameter, water flow control system, and instrumentation used to concurrently and nondestructively measure the infiltration rate (flow pump and outflow transducer), volumetric water content (time domain reflectometry), and matric suction (tensiometers) in flight during steady-state infiltration. A companion paper focuses on definition of the SWRC and K function for a clay soil using the procedures described in this paper. While conventional geotechnical centrifuges are used to reproduce the response of earth structure prototypes, the centrifuge developed in this study is used to accelerate flow processes. Accordingly, it required a comparatively small radius (0.7 m) but high angular velocity (up to 875 rpm or 600 g’s) to impart a wide range of hydraulic gradients to an unsaturated soil specimen. Analytical solutions to Richards’ equation in the centrifuge indicate that steady-state infiltration allows direct determination of the relationships between suction, volumetric water content, and hydraulic conductivity from the instrumentation results. Typical instrumentation results during a drying stage are presented to illustrate determination of data points on the SWRC and K function at steady state. These results were found to be consistent with analytical flow solutions. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1051_s1?isAuthorized=no [article] Centrifuge permeameter for unsaturated soils. I, Theoretical basis and experimental developments [texte imprimé] / Jorge G. Zornberg, Auteur ; John S. McCartney, Auteur . - 2010 . - pp. 1051-1063. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1051-1063 Mots-clés : Unsaturated  soils  Centrifuge  permeameter  Hydraulic  conductivity  function  Soil  water  retention  curve  TDR  Tensiometers Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A new centrifuge permeameter was developed with the specific objective of expediting the measurement of the hydraulic characteristics of unsaturated soils. The development, theoretical basis, and typical results associated with using the centrifuge permeameter for concurrent determination of the soil-water retention curve (SWRC) and hydraulic conductivity function (K function) of unsaturated soils are presented in this paper. Components developed for the centrifuge permeameter are described, including the centrifuge, permeameter, water flow control system, and instrumentation used to concurrently and nondestructively measure the infiltration rate (flow pump and outflow transducer), volumetric water content (time domain reflectometry), and matric suction (tensiometers) in flight during steady-state infiltration. A companion paper focuses on definition of the SWRC and K function for a clay soil using the procedures described in this paper. While conventional geotechnical centrifuges are used to reproduce the response of earth structure prototypes, the centrifuge developed in this study is used to accelerate flow processes. Accordingly, it required a comparatively small radius (0.7 m) but high angular velocity (up to 875 rpm or 600 g’s) to impart a wide range of hydraulic gradients to an unsaturated soil specimen. Analytical solutions to Richards’ equation in the centrifuge indicate that steady-state infiltration allows direct determination of the relationships between suction, volumetric water content, and hydraulic conductivity from the instrumentation results. Typical instrumentation results during a drying stage are presented to illustrate determination of data points on the SWRC and K function at steady state. These results were found to be consistent with analytical flow solutions. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1051_s1?isAuthorized=no

Centrifuge permeameter for unsaturated soils. II, Measurement of the hydraulic characteristics of an unsaturated clay / John S. McCartney in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 8 (Août 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1064-1076 Titre : Centrifuge permeameter for unsaturated soils. II, Measurement of the hydraulic characteristics of an unsaturated clay Type de document : texte imprimé Auteurs : John S. McCartney, Auteur ; Jorge G. Zornberg, Auteur Année de publication : 2010 Article en page(s) : pp. 1064-1076 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Centrifuge  permeameter  Unsaturated  soils  Hydraulic  conductivity  function  Soil  water  retention  curve Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper presents the hydraulic characteristics of an unsaturated, compacted clay, including its soil-water retention curve (SWRC) and hydraulic conductivity function (K function), determined using a new centrifuge permeameter developed at the University of Texas at Austin. A companion paper describes the apparatus, its instrumentation layout, and data reduction procedures. Three approaches are evaluated in this study to define the SWRC and K function of the compacted clay under both drying and wetting paths, by varying the inflow rate, the g level, or both. For imposed inflow rates ranging from 20 to 0.1 mL/h and g levels ranging from 10 to 100 g, the measured matric suction ranged from 5 to 70 kPa, the average volumetric water content ranged from 23 to 33%, and the hydraulic conductivity ranged from 2×10−7 to 8×10−11 m/s. The SWRCs and K functions obtained using the three different testing approaches were very consistent, and yielded suitable information for direct determination of the hydraulic characteristics. The approaches differed in the time required to complete a testing stage and in the range of measured hydraulic conductivity values. The g level had a negligible effect on the measured hydraulic characteristics of the compacted clay. The SWRCs and K functions defined using the centrifuge permeameter are consistent with those obtained using pressure chamber and column infiltration tests. The K functions defined using the centrifuge permeameter follow the same shape as those obtained from predictive relationships, although the measured and predicted K functions differ by two orders of magnitude at the lower end of the volumetric water content range. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1064_s1?isAuthorized=no [article] Centrifuge permeameter for unsaturated soils. II, Measurement of the hydraulic characteristics of an unsaturated clay [texte imprimé] / John S. McCartney, Auteur ; Jorge G. Zornberg, Auteur . - 2010 . - pp. 1064-1076. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1064-1076 Mots-clés : Centrifuge  permeameter  Unsaturated  soils  Hydraulic  conductivity  function  Soil  water  retention  curve Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This paper presents the hydraulic characteristics of an unsaturated, compacted clay, including its soil-water retention curve (SWRC) and hydraulic conductivity function (K function), determined using a new centrifuge permeameter developed at the University of Texas at Austin. A companion paper describes the apparatus, its instrumentation layout, and data reduction procedures. Three approaches are evaluated in this study to define the SWRC and K function of the compacted clay under both drying and wetting paths, by varying the inflow rate, the g level, or both. For imposed inflow rates ranging from 20 to 0.1 mL/h and g levels ranging from 10 to 100 g, the measured matric suction ranged from 5 to 70 kPa, the average volumetric water content ranged from 23 to 33%, and the hydraulic conductivity ranged from 2×10−7 to 8×10−11 m/s. The SWRCs and K functions obtained using the three different testing approaches were very consistent, and yielded suitable information for direct determination of the hydraulic characteristics. The approaches differed in the time required to complete a testing stage and in the range of measured hydraulic conductivity values. The g level had a negligible effect on the measured hydraulic characteristics of the compacted clay. The SWRCs and K functions defined using the centrifuge permeameter are consistent with those obtained using pressure chamber and column infiltration tests. The K functions defined using the centrifuge permeameter follow the same shape as those obtained from predictive relationships, although the measured and predicted K functions differ by two orders of magnitude at the lower end of the volumetric water content range. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1064_s1?isAuthorized=no

Empirical methodology to estimate seismically induced settlement of partially saturated sand / Majid Ghayoomi in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 3 (Mars 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 3 (Mars 2013) . - pp. 367-376 Titre : Empirical methodology to estimate seismically induced settlement of partially saturated sand Type de document : texte imprimé Auteurs : Majid Ghayoomi, Auteur ; John S. McCartney, Auteur ; Hon-Yim Ko, Auteur Année de publication : 2013 Article en page(s) : pp. 367-376 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : settlement;  earthquake  engineering;  design;  centrifuge  models  saturated  soils;  sand  (soil  type);  seismic  effects Résumé : Settlement of soil layers during and after earthquake shaking is a major cause of damage to buildings and geotechnical structures. The available empirical design methods to consider seismically induced settlement focus on sands in dry or water-saturated conditions, and there is currently a gap in the basic understanding of the mechanisms of seismically induced settlements of partially saturated sands. An effective stress-based empirical methodology is proposed to estimate the seismically induced settlement of a free-field layer of sand in partially saturated conditions. This approach estimates the settlement by separately considering the volumetric strains caused by compression of void space during strong shaking (seismic compression) and dissipation of excess pore water pressures generated during earthquake shaking (postcyclic reconsolidation). A parametric evaluation of the methodology indicates that the small strain shear modulus, the parameters of the modulus reduction curve, the approach to estimate the upper bound on volumetric strain during liquefaction, and the pore water pressure generation parameter can have significant impacts on the predicted settlement. The model predictions were validated using results from a newly developed centrifuge physical modeling system that involved the use of steady-state infiltration to maintain a uniform degree of saturation with depth in the sand layer. Both the model and experimental results show a nonlinear trend in surface settlement with degree of saturation, with a minimum value obtained for sand at a degree of saturation between 0.3 and 0.6. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000774 [article] Empirical methodology to estimate seismically induced settlement of partially saturated sand [texte imprimé] / Majid Ghayoomi, Auteur ; John S. McCartney, Auteur ; Hon-Yim Ko, Auteur . - 2013 . - pp. 367-376. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 3 (Mars 2013) . - pp. 367-376 Mots-clés : settlement;  earthquake  engineering;  design;  centrifuge  models  saturated  soils;  sand  (soil  type);  seismic  effects Résumé : Settlement of soil layers during and after earthquake shaking is a major cause of damage to buildings and geotechnical structures. The available empirical design methods to consider seismically induced settlement focus on sands in dry or water-saturated conditions, and there is currently a gap in the basic understanding of the mechanisms of seismically induced settlements of partially saturated sands. An effective stress-based empirical methodology is proposed to estimate the seismically induced settlement of a free-field layer of sand in partially saturated conditions. This approach estimates the settlement by separately considering the volumetric strains caused by compression of void space during strong shaking (seismic compression) and dissipation of excess pore water pressures generated during earthquake shaking (postcyclic reconsolidation). A parametric evaluation of the methodology indicates that the small strain shear modulus, the parameters of the modulus reduction curve, the approach to estimate the upper bound on volumetric strain during liquefaction, and the pore water pressure generation parameter can have significant impacts on the predicted settlement. The model predictions were validated using results from a newly developed centrifuge physical modeling system that involved the use of steady-state infiltration to maintain a uniform degree of saturation with depth in the sand layer. Both the model and experimental results show a nonlinear trend in surface settlement with degree of saturation, with a minimum value obtained for sand at a degree of saturation between 0.3 and 0.6. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000774

Impact of hydraulic hysteresis on the small-strain shear modulus of low plasticity soils / Ali Khosravi in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 11 (Novembre 2012) 

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