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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 [...]

Behavior of geogrid-sand interface in direct shear mode / Chia-Nan Liu in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 12 (Décembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1863–1871 Titre : Behavior of geogrid-sand interface in direct shear mode Type de document : texte imprimé Auteurs : Chia-Nan Liu, Auteur ; Jorge G. Zornberg, Auteur ; Tsong-Chia Chen, Auteur Année de publication : 2010 Article en page(s) : pp. 1863–1871 Note générale : Geotechnicql and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Shear  testsGeogridsGeosyntheticsInterfacesSandSoil  type Résumé : The contribution of transverse ribs to the soil-geogrids interaction under pullout mode has been well documented. However, the contribution of transverse ribs to the soil-geogrid interaction under direct shear mode is, at best, unclear. Consequently, this paper presents the results of a comprehensive direct shear testing program aimed at evaluating the contribution of transverse ribs to the interface shear. The direct shear tests involved Ottawa sand and several polyester geogrids with a variety of material tensile strength, percent open area, and aperture pattern. The test results show that the shear strength of sand-geogrid interfaces under direct shear mode is significantly higher than that of sand-geotextile interfaces. Analysis of shear displacement-strength response of the interfaces indicates that, in addition to interface shear components due to sand-rib friction and sand-sand shear at the location of the openings, the transverse ribs provide additional contribution to the overall sand-geogrid interface resistance. Specifically, analysis of the results reveals that the transverse ribs of the geogrid used in this study provide approximately 10% of interface shear resistance. This contribution is positively correlated with the tensile strength and the stiffness of geogrid ribs, but is negatively correlated with the percent open area of the geogrid. A simple model is proposed to quantify the contribution of transverse ribs to the interface shear strength under direct shear mode. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000150 [article] Behavior of geogrid-sand interface in direct shear mode [texte imprimé] / Chia-Nan Liu, Auteur ; Jorge G. Zornberg, Auteur ; Tsong-Chia Chen, Auteur . - 2010 . - pp. 1863–1871. Geotechnicql and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1863–1871 Mots-clés : Shear  testsGeogridsGeosyntheticsInterfacesSandSoil  type Résumé : The contribution of transverse ribs to the soil-geogrids interaction under pullout mode has been well documented. However, the contribution of transverse ribs to the soil-geogrid interaction under direct shear mode is, at best, unclear. Consequently, this paper presents the results of a comprehensive direct shear testing program aimed at evaluating the contribution of transverse ribs to the interface shear. The direct shear tests involved Ottawa sand and several polyester geogrids with a variety of material tensile strength, percent open area, and aperture pattern. The test results show that the shear strength of sand-geogrid interfaces under direct shear mode is significantly higher than that of sand-geotextile interfaces. Analysis of shear displacement-strength response of the interfaces indicates that, in addition to interface shear components due to sand-rib friction and sand-sand shear at the location of the openings, the transverse ribs provide additional contribution to the overall sand-geogrid interface resistance. Specifically, analysis of the results reveals that the transverse ribs of the geogrid used in this study provide approximately 10% of interface shear resistance. This contribution is positively correlated with the tensile strength and the stiffness of geogrid ribs, but is negatively correlated with the percent open area of the geogrid. A simple model is proposed to quantify the contribution of transverse ribs to the interface shear strength under direct shear mode. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000150

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

Failure mechanisms in sand over a deep active trapdoor / Yuri D. Costa in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 11 (Novembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1741–1753 Titre : Failure mechanisms in sand over a deep active trapdoor Type de document : texte imprimé Auteurs : Yuri D. Costa, Auteur ; Jorge G. Zornberg, Auteur ; Benedito S. Bueno, Auteur Année de publication : 2009 Article en page(s) : pp. 1741–1753 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : FailuresArchesBuried  pipesModel  testsSandSoil  type Résumé : An experimental testing program was undertaken to investigate failure mechanisms induced by the active movement of a deep rectangular trapdoor underlying a granular soil. Reduced-scale models were tested under normal gravity as well as under an increased gravitational field using a centrifuge facility. Some models were used to evaluate the performance of both flexible and rigid pipes undergoing a localized loss of support. Failure mechanisms in the longitudinal direction of the models were characterized by a single, well-defined failure surface that developed within the limits of the trapdoor. However, failure mechanisms in the transverse direction of the models were characterized by multiple failure surfaces extending outside the limits of the trapdoor. Significant dilation of the soil located immediately above the trapdoor was identified in the failure of the models. The pattern of the failure mechanisms was found to be affected by the stress level and backfill density. Higher stress levels were found to lead to well-developed failure zones. The influence of backfill density was found to be more relevant in models involving flexible pipes. Pipes embedded within loose backfill were severely damaged after loss of support, while pipes embedded in dense backfill experienced negligible deformations. These results indicate that damage to pipelines caused by ground loss of support can be significantly minimized by controlling the compaction of the fill. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000134 [article] Failure mechanisms in sand over a deep active trapdoor [texte imprimé] / Yuri D. Costa, Auteur ; Jorge G. Zornberg, Auteur ; Benedito S. Bueno, Auteur . - 2009 . - pp. 1741–1753. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1741–1753 Mots-clés : FailuresArchesBuried  pipesModel  testsSandSoil  type Résumé : An experimental testing program was undertaken to investigate failure mechanisms induced by the active movement of a deep rectangular trapdoor underlying a granular soil. Reduced-scale models were tested under normal gravity as well as under an increased gravitational field using a centrifuge facility. Some models were used to evaluate the performance of both flexible and rigid pipes undergoing a localized loss of support. Failure mechanisms in the longitudinal direction of the models were characterized by a single, well-defined failure surface that developed within the limits of the trapdoor. However, failure mechanisms in the transverse direction of the models were characterized by multiple failure surfaces extending outside the limits of the trapdoor. Significant dilation of the soil located immediately above the trapdoor was identified in the failure of the models. The pattern of the failure mechanisms was found to be affected by the stress level and backfill density. Higher stress levels were found to lead to well-developed failure zones. The influence of backfill density was found to be more relevant in models involving flexible pipes. Pipes embedded within loose backfill were severely damaged after loss of support, while pipes embedded in dense backfill experienced negligible deformations. These results indicate that damage to pipelines caused by ground loss of support can be significantly minimized by controlling the compaction of the fill. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000134

Mobilization of reinforcement forces in fiber-reinforced soil / Chunling Li in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 1 (Janvier 2013) 

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Reliability-based design for external stability of narrow mechanically stabilized earth walls / Kuo-Hsin Yang in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 3 (Mars 2011) 

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