Dépouillements

Shear strength of municipal solid waste / Bray, Jonathan D. in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 709–722 Titre : Shear strength of municipal solid waste Type de document : texte imprimé Auteurs : Bray, Jonathan D., Auteur ; Dimitrios Zekkos, Auteur ; Edward Jr Kavazanjian, Auteur Année de publication : 2009 Article en page(s) : pp. 709–722 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Dynamic  properties  Municipal  wastes  Solid  wastes  Landfills  Shear  strength  Stress  strain  relations  Laboratory  tests Résumé : A comprehensive large-scale laboratory testing program using direct shear (DS), triaxial (TX), and simple shear tests was performed on municipal solid waste (MSW) retrieved from a landfill in the San Francisco Bay area to develop insights about and a framework for interpretation of the shear strength of MSW. Stability analyses of MSW landfills require characterization of the shear strength of MSW. Although MSW is variable and a difficult material to test, its shear strength can be evaluated rationally to develop reasonable estimates. The effects of waste composition, fibrous particle orientation, confining stress, rate of loading, stress path, stress-strain compatibility, and unit weight on the shear strength of MSW were evaluated in the testing program described herein. The results of this testing program indicate that the DS test is appropriate to evaluate the shear strength of MSW along its weakest orientation (i.e., on a plane parallel to the preferred orientation of the larger fibrous particles within MSW). These laboratory results and the results of more than 100 large-scale laboratory tests from other studies indicate that the DS static shear strength of MSW is best characterized by a cohesion of 15kPa and a friction angle of 36° at normal stress of 1atm with the friction angle decreasing by 5° for every log cycle increase in normal stress. Other shearing modes that engage the fibrous materials within MSW (e.g., TX) produce higher friction angles. The dynamic shear strength of MSW can be estimated conservatively to be 20% greater than its static strength. These recommendations are based on tests of MSW with a moisture content below its field capacity; therefore, cyclic degradation due to pore pressure generation has not been considered in its development. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000063 [article] Shear strength of municipal solid waste [texte imprimé] / Bray, Jonathan D., Auteur ; Dimitrios Zekkos, Auteur ; Edward Jr Kavazanjian, Auteur . - 2009 . - pp. 709–722. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 709–722 Mots-clés : Dynamic  properties  Municipal  wastes  Solid  wastes  Landfills  Shear  strength  Stress  strain  relations  Laboratory  tests Résumé : A comprehensive large-scale laboratory testing program using direct shear (DS), triaxial (TX), and simple shear tests was performed on municipal solid waste (MSW) retrieved from a landfill in the San Francisco Bay area to develop insights about and a framework for interpretation of the shear strength of MSW. Stability analyses of MSW landfills require characterization of the shear strength of MSW. Although MSW is variable and a difficult material to test, its shear strength can be evaluated rationally to develop reasonable estimates. The effects of waste composition, fibrous particle orientation, confining stress, rate of loading, stress path, stress-strain compatibility, and unit weight on the shear strength of MSW were evaluated in the testing program described herein. The results of this testing program indicate that the DS test is appropriate to evaluate the shear strength of MSW along its weakest orientation (i.e., on a plane parallel to the preferred orientation of the larger fibrous particles within MSW). These laboratory results and the results of more than 100 large-scale laboratory tests from other studies indicate that the DS static shear strength of MSW is best characterized by a cohesion of 15kPa and a friction angle of 36° at normal stress of 1atm with the friction angle decreasing by 5° for every log cycle increase in normal stress. Other shearing modes that engage the fibrous materials within MSW (e.g., TX) produce higher friction angles. The dynamic shear strength of MSW can be estimated conservatively to be 20% greater than its static strength. These recommendations are based on tests of MSW with a moisture content below its field capacity; therefore, cyclic degradation due to pore pressure generation has not been considered in its development. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000063

Blast densification / Guillermo A. Narsilio in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 723–734 Titre : Blast densification : multi-instrumented case history Type de document : texte imprimé Auteurs : Guillermo A. Narsilio, Auteur ; J. Carlos Santamarina, Auteur ; Tamara Hebeler, Auteur Année de publication : 2009 Article en page(s) : pp. 723–734 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Blasting  Soil  stabilization  Settlement  Measurement  Soil  liquefaction  South  Carolina Résumé : A comprehensive blast densification field study was conducted at a test site in South Carolina to densify a loose soil layer at a depth between z=8–13m . The study included extensive laboratory and field characterizations and four carefully monitored blast events. Results revealed that densification is not an instantaneous phenomenon; underlying time-dependent processes involve resedimentation, drainage of excess pore pressure as the granular skeleton deforms and the effective stress recovers, and secondary settlement effects, which do not involve excess pore pressure dissipation. The degree of densification decreased in successive blasting events, and the soil gradually evolved toward an asymptotical terminal density associated with blast densification. The blasting sequence and detonation delays appeared to have a minor effect on shear-induced movements. The increase in penetration resistance manifested 2years after four blasting-drainage events. Instead, surface settlement using standard surveying techniques, subsurface deformation assessment, and subsurface pore fluid pressure monitoring provided valuable, real-time indicators of the soil response to the blasting events. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000023 [article] Blast densification : multi-instrumented case history [texte imprimé] / Guillermo A. Narsilio, Auteur ; J. Carlos Santamarina, Auteur ; Tamara Hebeler, Auteur . - 2009 . - pp. 723–734. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 723–734 Mots-clés : Blasting  Soil  stabilization  Settlement  Measurement  Soil  liquefaction  South  Carolina Résumé : A comprehensive blast densification field study was conducted at a test site in South Carolina to densify a loose soil layer at a depth between z=8–13m . The study included extensive laboratory and field characterizations and four carefully monitored blast events. Results revealed that densification is not an instantaneous phenomenon; underlying time-dependent processes involve resedimentation, drainage of excess pore pressure as the granular skeleton deforms and the effective stress recovers, and secondary settlement effects, which do not involve excess pore pressure dissipation. The degree of densification decreased in successive blasting events, and the soil gradually evolved toward an asymptotical terminal density associated with blast densification. The blasting sequence and detonation delays appeared to have a minor effect on shear-induced movements. The increase in penetration resistance manifested 2years after four blasting-drainage events. Instead, surface settlement using standard surveying techniques, subsurface deformation assessment, and subsurface pore fluid pressure monitoring provided valuable, real-time indicators of the soil response to the blasting events. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000023

Correcting liquefaction resistance for aged sands using measured to estimated velocity ratio / Ronald D. Andrus in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 735–744 Titre : Correcting liquefaction resistance for aged sands using measured to estimated velocity ratio Type de document : texte imprimé Auteurs : Ronald D. Andrus, Auteur ; Hossein Hayati, Auteur ; Nisha P. Mohanan, Auteur Année de publication : 2009 Article en page(s) : pp. 735–744 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Aging  Sand  Cone  penetration  tests  Earthquakes  In  situ  tests  Soil  liquefaction  Wave  velocity  Penetration  tests Résumé : Factors for correcting liquefaction resistance for aged sands using ratios of measured to estimated shear-wave velocity (MEVR) are derived in this paper. Estimated values of shear-wave velocity (VS) are computed for 91 penetration resistance- VS data pairs using previously published relationships. Linear regression is performed on values of MEVR and corresponding average age. Age of the sand layer is taken as the time between VS measurements and initial deposition or last critical disturbance. It is found that MEVR increases by a factor of about 0.08 per log cycle of time, and time equals about 6years on average when MEVR equals 1 for the recommended penetration resistance- VS relationships. The resulting regression equation is combined with the strength gain equation reported by Hayati et al. 2008 in “Proc., Geotechnical Earthquake Engineering and Soil Dynamics IV,” to produce a MEVR versus deposit resistance correction relationship. This new corrective relationship is applied to create liquefaction resistance curves based on VS , standard penetration test blow count, and cone tip resistance for sands of various ages (or MEVRs). Because age of natural soil deposits is usually difficult to accurately determine, MEVR appears to be a promising alternative. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000025 [article] Correcting liquefaction resistance for aged sands using measured to estimated velocity ratio [texte imprimé] / Ronald D. Andrus, Auteur ; Hossein Hayati, Auteur ; Nisha P. Mohanan, Auteur . - 2009 . - pp. 735–744. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 735–744 Mots-clés : Aging  Sand  Cone  penetration  tests  Earthquakes  In  situ  tests  Soil  liquefaction  Wave  velocity  Penetration  tests Résumé : Factors for correcting liquefaction resistance for aged sands using ratios of measured to estimated shear-wave velocity (MEVR) are derived in this paper. Estimated values of shear-wave velocity (VS) are computed for 91 penetration resistance- VS data pairs using previously published relationships. Linear regression is performed on values of MEVR and corresponding average age. Age of the sand layer is taken as the time between VS measurements and initial deposition or last critical disturbance. It is found that MEVR increases by a factor of about 0.08 per log cycle of time, and time equals about 6years on average when MEVR equals 1 for the recommended penetration resistance- VS relationships. The resulting regression equation is combined with the strength gain equation reported by Hayati et al. 2008 in “Proc., Geotechnical Earthquake Engineering and Soil Dynamics IV,” to produce a MEVR versus deposit resistance correction relationship. This new corrective relationship is applied to create liquefaction resistance curves based on VS , standard penetration test blow count, and cone tip resistance for sands of various ages (or MEVRs). Because age of natural soil deposits is usually difficult to accurately determine, MEVR appears to be a promising alternative. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000025

Learning of dnamic soil behavior from downhole arrays / Chi-Chin Tsai in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 745–757 Titre : Learning of dnamic soil behavior from downhole arrays Type de document : texte imprimé Auteurs : Chi-Chin Tsai, Auteur ; Youssef M. Hashash, Auteur Année de publication : 2009 Article en page(s) : pp. 745–757 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Dynamic  properties  Neural  networks  Shear  modulus  Shear  strain Résumé : An increasing number of downhole arrays are deployed to measure motions at the ground surface and within the soil profile. Measurements from these arrays provide an opportunity to improve site response models and to better understand underlying dynamic soil behavior. Parametric inverse analysis approaches have been used to identify constitutive model parameters to achieve a better match with field observations. However, they are limited by the selected material model. Nonparametric inverse analysis approaches identify averaged soil behavior between measurement locations. A novel inverse analysis framework, self-learning simulations (SelfSim), is employed to reproduce the measured downhole array response while extracting the underlying soil behavior of individual soil layers unconstrained by prior assumptions of soil behavior. SelfSim is successfully applied to recordings from Lotung and La Cienega. The extracted soil behavior from few events can be used to reliably predict the measured response for other events. The field extracted soil behavior shows dependencies of shear modulus and damping on cyclic shear strain level, number of loading cycles, and strain rate that are similar qualitatively to those reported from laboratory studies but differ quantitatively. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000050 [article] Learning of dnamic soil behavior from downhole arrays [texte imprimé] / Chi-Chin Tsai, Auteur ; Youssef M. Hashash, Auteur . - 2009 . - pp. 745–757. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 745–757 Mots-clés : Dynamic  properties  Neural  networks  Shear  modulus  Shear  strain Résumé : An increasing number of downhole arrays are deployed to measure motions at the ground surface and within the soil profile. Measurements from these arrays provide an opportunity to improve site response models and to better understand underlying dynamic soil behavior. Parametric inverse analysis approaches have been used to identify constitutive model parameters to achieve a better match with field observations. However, they are limited by the selected material model. Nonparametric inverse analysis approaches identify averaged soil behavior between measurement locations. A novel inverse analysis framework, self-learning simulations (SelfSim), is employed to reproduce the measured downhole array response while extracting the underlying soil behavior of individual soil layers unconstrained by prior assumptions of soil behavior. SelfSim is successfully applied to recordings from Lotung and La Cienega. The extracted soil behavior from few events can be used to reliably predict the measured response for other events. The field extracted soil behavior shows dependencies of shear modulus and damping on cyclic shear strain level, number of loading cycles, and strain rate that are similar qualitatively to those reported from laboratory studies but differ quantitatively. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000050

Centrifuge modeling of slope ionstability / Ling, Hoe I. in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 758–767 Titre : Centrifuge modeling of slope ionstability Type de document : texte imprimé Auteurs : Ling, Hoe I., Auteur ; Min-Hao Wu, Auteur ; Leshchinsky, Dov, Auteur Année de publication : 2009 Article en page(s) : pp. 758–767 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Slope  stability  Centrifuge  models  Limit  equilibrium  Rainfall  intensity  Clays  Sand  Mixtures Résumé : This paper demonstrates the use of a centrifuge modeling technique in studying slope instability. The slope models were prepared from sand, and sand mixed with 15 and 30% fines by weight, compacted at optimum water content. The validity of the modeling technique was confirmed using slope models of different heights, inclinations, and soil types. The soil behavior was studied under triaxial and plane strain conditions, and the extended Mohr-Coulomb failure criterion was found relevant for expressing the strength of unsaturated compacted soil based on the angle of internal friction and apparent cohesion. The Bishop’s circular mechanism, together with the extended Mohr-Coulomb failure criterion, was able to simulate the slope failure reasonably well. The rainfall of different intensities was then induced on the 60° stable slopes of sand with 15% fines. It was found that the failure of slope under rainfall may be interpreted as a reduction in apparent cohesion. The centrifuge tests also allowed the rainfall intensity-duration threshold curve (local curve) to be generated for the test slopes, and the accumulated rainfall corresponded well to some of the reported field observations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000024 [article] Centrifuge modeling of slope ionstability [texte imprimé] / Ling, Hoe I., Auteur ; Min-Hao Wu, Auteur ; Leshchinsky, Dov, Auteur . - 2009 . - pp. 758–767. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 758–767 Mots-clés : Slope  stability  Centrifuge  models  Limit  equilibrium  Rainfall  intensity  Clays  Sand  Mixtures Résumé : This paper demonstrates the use of a centrifuge modeling technique in studying slope instability. The slope models were prepared from sand, and sand mixed with 15 and 30% fines by weight, compacted at optimum water content. The validity of the modeling technique was confirmed using slope models of different heights, inclinations, and soil types. The soil behavior was studied under triaxial and plane strain conditions, and the extended Mohr-Coulomb failure criterion was found relevant for expressing the strength of unsaturated compacted soil based on the angle of internal friction and apparent cohesion. The Bishop’s circular mechanism, together with the extended Mohr-Coulomb failure criterion, was able to simulate the slope failure reasonably well. The rainfall of different intensities was then induced on the 60° stable slopes of sand with 15% fines. It was found that the failure of slope under rainfall may be interpreted as a reduction in apparent cohesion. The centrifuge tests also allowed the rainfall intensity-duration threshold curve (local curve) to be generated for the test slopes, and the accumulated rainfall corresponded well to some of the reported field observations. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000024

Efficient evaluation of reliability for slopes with circular slip surfaces using importance sampling / Jianye Ching in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 768–777 Titre : Efficient evaluation of reliability for slopes with circular slip surfaces using importance sampling Type de document : texte imprimé Auteurs : Jianye Ching, Auteur ; Phoon, Kok-Kwang, Auteur ; Yu-Gang Hu, Auteur Année de publication : 2009 Article en page(s) : pp. 768–777 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Slope  stability  Monte  Carlo  method  System  reliability  Sampling Résumé : Evaluating the reliability of a slope is a challenging task because the possible slip surface is not known beforehand. Approximate methods via the first-order reliability method provide efficient ways of evaluating failure probability of the “most probable” failure surface. The tradeoff is that the failure probability estimates may be biased towards the unconservative side. The Monte Carlo simulation (MCS) is a viable unbiased way of estimating the failure probability of a slope, but MCS is inefficient for problems with small failure probabilities. This study proposes a novel way based on the importance sampling technique of estimating slope reliability that is unbiased and yet is much more efficient than MCS. In particular, the critical issue of the specification of the importance sampling probability density function will be addressed in detail. Three examples of slope reliability will be used to demonstrate the performance of the new method. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000035 [article] Efficient evaluation of reliability for slopes with circular slip surfaces using importance sampling [texte imprimé] / Jianye Ching, Auteur ; Phoon, Kok-Kwang, Auteur ; Yu-Gang Hu, Auteur . - 2009 . - pp. 768–777. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 768–777 Mots-clés : Slope  stability  Monte  Carlo  method  System  reliability  Sampling Résumé : Evaluating the reliability of a slope is a challenging task because the possible slip surface is not known beforehand. Approximate methods via the first-order reliability method provide efficient ways of evaluating failure probability of the “most probable” failure surface. The tradeoff is that the failure probability estimates may be biased towards the unconservative side. The Monte Carlo simulation (MCS) is a viable unbiased way of estimating the failure probability of a slope, but MCS is inefficient for problems with small failure probabilities. This study proposes a novel way based on the importance sampling technique of estimating slope reliability that is unbiased and yet is much more efficient than MCS. In particular, the critical issue of the specification of the importance sampling probability density function will be addressed in detail. Three examples of slope reliability will be used to demonstrate the performance of the new method. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000035

Analytical method for load-transfer characteristics of rock-socketed drilled shafts / Hoonil Seol in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 778–789 Titre : Analytical method for load-transfer characteristics of rock-socketed drilled shafts Type de document : texte imprimé Auteurs : Hoonil Seol, Auteur ; Sangseom Jeong, Auteur ; Sunghan Cho, Auteur Année de publication : 2009 Article en page(s) : pp. 778–789 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Drilled  shafts  Load  transfer  Stiffness  Roughness  Load  distribution  Rocks  Deformation Résumé : The load-settlement behavior of rock-socketed drilled shafts under axial loading is investigated by a load-transfer approach. Special attention is given to the shear load-transfer function and an analytical method for estimating load-transfer characteristics of rock-socketed drilled shafts. A nonlinear triple curve is employed to determine the shear load-transfer function of rock-socketed drilled shafts based on the constant normal stiffness direct shear tests and the Hoek-Brown failure criterion. An analytical method that takes into account the soil coupling effect was developed using a modified Mindlin’s point load solution. Through comparisons with field case studies, it is found that the proposed methodology in the present study is in good agreement with the general trend observed by in situ measurements and, thus, represents a significant improvement in the prediction of drilled shaft shear behavior. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A6%2877 [...] [article] Analytical method for load-transfer characteristics of rock-socketed drilled shafts [texte imprimé] / Hoonil Seol, Auteur ; Sangseom Jeong, Auteur ; Sunghan Cho, Auteur . - 2009 . - pp. 778–789. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 778–789 Mots-clés : Drilled  shafts  Load  transfer  Stiffness  Roughness  Load  distribution  Rocks  Deformation Résumé : The load-settlement behavior of rock-socketed drilled shafts under axial loading is investigated by a load-transfer approach. Special attention is given to the shear load-transfer function and an analytical method for estimating load-transfer characteristics of rock-socketed drilled shafts. A nonlinear triple curve is employed to determine the shear load-transfer function of rock-socketed drilled shafts based on the constant normal stiffness direct shear tests and the Hoek-Brown failure criterion. An analytical method that takes into account the soil coupling effect was developed using a modified Mindlin’s point load solution. Through comparisons with field case studies, it is found that the proposed methodology in the present study is in good agreement with the general trend observed by in situ measurements and, thus, represents a significant improvement in the prediction of drilled shaft shear behavior. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A6%2877 [...]

Shaft capacity of continuous flight auger piles in sand / K. G. Gavin in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 790–798 Titre : Shaft capacity of continuous flight auger piles in sand Type de document : texte imprimé Auteurs : K. G. Gavin, Auteur ; D. Cadogan, Auteur ; P. Casey, Auteur Année de publication : 2009 Article en page(s) : pp. 790–798 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Piles  Displacement  Shafts  Sand  Field  tests Résumé : This paper presents the results of a series of field experiments performed to study the development of shaft resistance on continuous flight auger piles installed in sand. The test piles were instrumented in order to separate the shaft and base resistance, and to allow the determination of the distribution of shaft resistance along the pile shaft. The tests highlighted the importance of accurate calculation of the shaft resistance for nondisplacement piles. At a typical maximum allowable pile head settlement of 25mm , more than 71% of the pile resistance was provided by shaft friction. Conventional methods of estimating shaft resistance were assessed. It was found that methods which incorporated parameters directly interpreted from in situ test results provided the most consistent estimates. In the final section, differences between the shaft resistances mobilized on displacement and nondisplacement piles are considered. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000073 [article] Shaft capacity of continuous flight auger piles in sand [texte imprimé] / K. G. Gavin, Auteur ; D. Cadogan, Auteur ; P. Casey, Auteur . - 2009 . - pp. 790–798. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 790–798 Mots-clés : Piles  Displacement  Shafts  Sand  Field  tests Résumé : This paper presents the results of a series of field experiments performed to study the development of shaft resistance on continuous flight auger piles installed in sand. The test piles were instrumented in order to separate the shaft and base resistance, and to allow the determination of the distribution of shaft resistance along the pile shaft. The tests highlighted the importance of accurate calculation of the shaft resistance for nondisplacement piles. At a typical maximum allowable pile head settlement of 25mm , more than 71% of the pile resistance was provided by shaft friction. Conventional methods of estimating shaft resistance were assessed. It was found that methods which incorporated parameters directly interpreted from in situ test results provided the most consistent estimates. In the final section, differences between the shaft resistances mobilized on displacement and nondisplacement piles are considered. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000073

Experimental response of piles in sand under compound motion / Jeramy C. Ashlock in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 799–808 Titre : Experimental response of piles in sand under compound motion Type de document : texte imprimé Auteurs : Jeramy C. Ashlock, Auteur ; Ronald Y. S. Pak, Auteur Année de publication : 2009 Article en page(s) : pp. 799–808 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Piles  Vibration  Soil-structure  interaction  Centrifuge  models  Dynamic  tests  Soil  dynamics Résumé : This paper describes a fundamental experimental study on the vertical, horizontal, and rocking dynamic behavior of single pile foundations in granular soils. Aimed at generating an extensive experimental database with sufficient parametric variations to clarify a number of issues, multiple series of canonical small-strain forced-vibration centrifuge tests were performed on two model piles using the technique of random vibration and impact loading. Correlated well with vertical- and horizontal-centric dynamic tests within the experimental program, a novel hybrid-mode test method by means of eccentric excitation is validated and employed for the characterization of the foundation responses in general planar motion. A large set of experimental data for different length scales were generated and synthesized in the frequency domain in the form of directional force-response transfer functions. By virtue of the physical measurements, the validity and limitations of two fundamental elastodynamic pile solutions pertaining to the physical dynamic soil-foundation problem are also evaluated. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000038 [article] Experimental response of piles in sand under compound motion [texte imprimé] / Jeramy C. Ashlock, Auteur ; Ronald Y. S. Pak, Auteur . - 2009 . - pp. 799–808. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 799–808 Mots-clés : Piles  Vibration  Soil-structure  interaction  Centrifuge  models  Dynamic  tests  Soil  dynamics Résumé : This paper describes a fundamental experimental study on the vertical, horizontal, and rocking dynamic behavior of single pile foundations in granular soils. Aimed at generating an extensive experimental database with sufficient parametric variations to clarify a number of issues, multiple series of canonical small-strain forced-vibration centrifuge tests were performed on two model piles using the technique of random vibration and impact loading. Correlated well with vertical- and horizontal-centric dynamic tests within the experimental program, a novel hybrid-mode test method by means of eccentric excitation is validated and employed for the characterization of the foundation responses in general planar motion. A large set of experimental data for different length scales were generated and synthesized in the frequency domain in the form of directional force-response transfer functions. By virtue of the physical measurements, the validity and limitations of two fundamental elastodynamic pile solutions pertaining to the physical dynamic soil-foundation problem are also evaluated. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000038

Design guidelines for polyethylene pipe interface shear resistance / Ömer Bilgin in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 809–818 Titre : Design guidelines for polyethylene pipe interface shear resistance Type de document : texte imprimé Auteurs : Ömer Bilgin, Auteur ; Harry E. Stewart, Auteur Année de publication : 2009 Article en page(s) : pp. 809–818 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Pipeline  design  Plastic  pipes  Interfaces  Pullout  resistance  Temperature  effects  Cyclic  strength  Cyclic  tests Résumé : Polyethylene pipes are commonly used in pipeline systems. Current methods used to determine the pipe pullout capacity do not consider the effects of diameter changes and cyclic movements that the pipelines may experience. Laboratory tests were performed to study the interface shearing resistance of polyethylene pipes under varying conditions. The tests were performed in a temperature-controlled room, where properties were investigated for thermal variations expected in the field. Two types of tests were performed: pull/push tests and cyclic tests. Test results indicated that reductions in pipe diameter affect the interface shear resistance that develops between the pipe and soil. As the pipe diameter gets smaller, the normal contact stresses at the interface decreases, causing a reduction in the interface shearing resistance directly proportional to the normal stress changes. Cyclic pipe movements also cause significant reduction in pipe pullout resistance. The test results indicated that the polyethylene pipe interface shear resistance can be significantly lower than the one determined using the current methods. This paper presents the test results, findings, and design recommendations for the pullout resistance of buried polyethylene pipes. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000030 [article] Design guidelines for polyethylene pipe interface shear resistance [texte imprimé] / Ömer Bilgin, Auteur ; Harry E. Stewart, Auteur . - 2009 . - pp. 809–818. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 809–818 Mots-clés : Pipeline  design  Plastic  pipes  Interfaces  Pullout  resistance  Temperature  effects  Cyclic  strength  Cyclic  tests Résumé : Polyethylene pipes are commonly used in pipeline systems. Current methods used to determine the pipe pullout capacity do not consider the effects of diameter changes and cyclic movements that the pipelines may experience. Laboratory tests were performed to study the interface shearing resistance of polyethylene pipes under varying conditions. The tests were performed in a temperature-controlled room, where properties were investigated for thermal variations expected in the field. Two types of tests were performed: pull/push tests and cyclic tests. Test results indicated that reductions in pipe diameter affect the interface shear resistance that develops between the pipe and soil. As the pipe diameter gets smaller, the normal contact stresses at the interface decreases, causing a reduction in the interface shearing resistance directly proportional to the normal stress changes. Cyclic pipe movements also cause significant reduction in pipe pullout resistance. The test results indicated that the polyethylene pipe interface shear resistance can be significantly lower than the one determined using the current methods. This paper presents the test results, findings, and design recommendations for the pullout resistance of buried polyethylene pipes. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000030

Effect of surface heave on response of partially embedded pipelines on clay / R. S. Merifield in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 819–829 Titre : Effect of surface heave on response of partially embedded pipelines on clay Type de document : texte imprimé Auteurs : R. S. Merifield, Auteur ; D. J. White, Auteur ; M. F. Randolph, Auteur Année de publication : 2009 Article en page(s) : pp. 819–829 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Pipelines  Clays  Plasticity  Offshore  structures  Finite  element  method  Soil  mechanics  Collapse  loads  Cohesive  soils  Embedment Résumé : The as-laid embedment of an on-bottom pipeline strongly influences the resulting thermal insulation, and the resistance to subsequent axial and lateral movement of the pipeline. Reliable assessment of these parameters is essential for the design of offshore pipelines. Static vertical penetration of a pipe into a soft clay seabed—which can be modeled as an undrained process—causes heave of soil on each side of the pipeline. The heaved soil contributes to the vertical penetration resistance and the horizontal capacity. This paper describes a series of large deformation finite-element analyses of pipe penetration, supported by a simple analytical assessment of the heave process. The conventional bearing capacity approach to the analysis of pipe penetration is reviewed, and modifications for the effects of soil weight and heave are presented. It is shown that in soft soil conditions—which are typical for deep water—the soil self-weight contributes a significant portion of the vertical penetration resistance and horizontal capacity. If heave is neglected, the soil weight leads to a vertical force due to buoyancy, based on Archimedes’ principle. When heave is considered, the soil weight contributes an additional component of vertical load, exceeding simple buoyancy, due to the distorted geometry of the soil surface. Archimedes’ principle does not apply. The finite-element analyses, benchmarked against rigorous plasticity solutions, are used to calibrate simple expressions for predicting static vertical pipe penetration, and the resulting horizontal capacity. These simple solutions allow the conventional bearing capacity approach to be used in a manner which correctly accounts for the effects of soil self-weight and heave. An approximate solution for predicting the “local” pipe embedment—relative to the raised soil level immediately adjacent to the pipe—is derived. The local embedment significantly exceeds the nominal embedment relative to the original soil surface. This effect counteracts the tendency for heave to reduce the embedment by raising the penetration resistance. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000070 [article] Effect of surface heave on response of partially embedded pipelines on clay [texte imprimé] / R. S. Merifield, Auteur ; D. J. White, Auteur ; M. F. Randolph, Auteur . - 2009 . - pp. 819–829. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 819–829 Mots-clés : Pipelines  Clays  Plasticity  Offshore  structures  Finite  element  method  Soil  mechanics  Collapse  loads  Cohesive  soils  Embedment Résumé : The as-laid embedment of an on-bottom pipeline strongly influences the resulting thermal insulation, and the resistance to subsequent axial and lateral movement of the pipeline. Reliable assessment of these parameters is essential for the design of offshore pipelines. Static vertical penetration of a pipe into a soft clay seabed—which can be modeled as an undrained process—causes heave of soil on each side of the pipeline. The heaved soil contributes to the vertical penetration resistance and the horizontal capacity. This paper describes a series of large deformation finite-element analyses of pipe penetration, supported by a simple analytical assessment of the heave process. The conventional bearing capacity approach to the analysis of pipe penetration is reviewed, and modifications for the effects of soil weight and heave are presented. It is shown that in soft soil conditions—which are typical for deep water—the soil self-weight contributes a significant portion of the vertical penetration resistance and horizontal capacity. If heave is neglected, the soil weight leads to a vertical force due to buoyancy, based on Archimedes’ principle. When heave is considered, the soil weight contributes an additional component of vertical load, exceeding simple buoyancy, due to the distorted geometry of the soil surface. Archimedes’ principle does not apply. The finite-element analyses, benchmarked against rigorous plasticity solutions, are used to calibrate simple expressions for predicting static vertical pipe penetration, and the resulting horizontal capacity. These simple solutions allow the conventional bearing capacity approach to be used in a manner which correctly accounts for the effects of soil self-weight and heave. An approximate solution for predicting the “local” pipe embedment—relative to the raised soil level immediately adjacent to the pipe—is derived. The local embedment significantly exceeds the nominal embedment relative to the original soil surface. This effect counteracts the tendency for heave to reduce the embedment by raising the penetration resistance. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000070

Use of SPT blow counts to estimate shear strength properties of soils / Hiroshan Hettiarachchi in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 830–834 Titre : Use of SPT blow counts to estimate shear strength properties of soils : energy balance approach Type de document : texte imprimé Auteurs : Hiroshan Hettiarachchi, Auteur ; Timothy Brown, Auteur Année de publication : 2009 Article en page(s) : pp. 830–834 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Penetration  tests  Shear  strength  Friction  Energy  Foundation  design Résumé : In foundation designs, standard penetration test (SPT) blow counts are typically used to estimate shear strength properties of soils. Few correlations are widely in use to make such estimations. However, the selection of these correlation equations are not often justified or explained. This manuscript describes a new approach to estimate the shear strength properties based on the SPT blow counts. The proposed method treats SPT analogous to driving a miniature open-ended pipe pile. During SPT, part of the energy is transferred into the soil. This energy is dissipated at the soil-sampler interface to overcome skin and point resistance to penetrate a sampler into the soil. Energy balance was used to correlate the SPT blow count to the shear strength properties of the soil at the depth of testing. Two separate equations were derived: one to estimate the friction angle (ϕ′) of sand and the other to estimate the undrained shear strength (cu) of clay. SPT results from two sites were used to calibrate the proposed equations, and then two other sets of data were used to verify them. With a low average standard deviation in the calibration process, the proposed N60−ϕ′ equation demonstrated a strong correlation. The proposed N60−cu equation did not provide as strong a correlation as the N60−ϕ′ equation. However, a statistical analysis revealed that for the data used in this research, both equations could estimate shear strength properties better than the commonly used, other existing correlations. The proposed equations may not work in very stiff clay or very dense sand and should not be used to analyze SPT results with poor recovery. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000016 [article] Use of SPT blow counts to estimate shear strength properties of soils : energy balance approach [texte imprimé] / Hiroshan Hettiarachchi, Auteur ; Timothy Brown, Auteur . - 2009 . - pp. 830–834. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 830–834 Mots-clés : Penetration  tests  Shear  strength  Friction  Energy  Foundation  design Résumé : In foundation designs, standard penetration test (SPT) blow counts are typically used to estimate shear strength properties of soils. Few correlations are widely in use to make such estimations. However, the selection of these correlation equations are not often justified or explained. This manuscript describes a new approach to estimate the shear strength properties based on the SPT blow counts. The proposed method treats SPT analogous to driving a miniature open-ended pipe pile. During SPT, part of the energy is transferred into the soil. This energy is dissipated at the soil-sampler interface to overcome skin and point resistance to penetrate a sampler into the soil. Energy balance was used to correlate the SPT blow count to the shear strength properties of the soil at the depth of testing. Two separate equations were derived: one to estimate the friction angle (ϕ′) of sand and the other to estimate the undrained shear strength (cu) of clay. SPT results from two sites were used to calibrate the proposed equations, and then two other sets of data were used to verify them. With a low average standard deviation in the calibration process, the proposed N60−ϕ′ equation demonstrated a strong correlation. The proposed N60−cu equation did not provide as strong a correlation as the N60−ϕ′ equation. However, a statistical analysis revealed that for the data used in this research, both equations could estimate shear strength properties better than the commonly used, other existing correlations. The proposed equations may not work in very stiff clay or very dense sand and should not be used to analyze SPT results with poor recovery. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000016

Experimental investigation on effectiveness of a vertical drain under cyclic loads / Buddhima Indraratna in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 835–839 Titre : Experimental investigation on effectiveness of a vertical drain under cyclic loads Type de document : texte imprimé Auteurs : Buddhima Indraratna, Auteur ; Anass Attya, Auteur ; Cholachat Rujikiatkamjorn, Auteur Année de publication : 2009 Article en page(s) : pp. 835–839 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Clays  Soil  consolidation  Drainage  Laboratory  tests  Repeated  loads  Cyclic  loads Résumé : This study examines the effectiveness of a prefabricated vertical drain (PVD) installed in reconstituted soft clay, where a large cyclic triaxial device was used to simulate repeated loading representing a rail track environment. The experimental data demonstrate that PVD successfully prevents excessive buildup of pore water pressure during cyclic loading, and that dissipation continues to occur after the load is removed. The findings of this study have direct relevance to rail track environments, e.g., in coastal Australia, where PVD installation beneath rail tracks constructed on low-lying estuarine soils has been recently introduced. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000006 [article] Experimental investigation on effectiveness of a vertical drain under cyclic loads [texte imprimé] / Buddhima Indraratna, Auteur ; Anass Attya, Auteur ; Cholachat Rujikiatkamjorn, Auteur . - 2009 . - pp. 835–839. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 835–839 Mots-clés : Clays  Soil  consolidation  Drainage  Laboratory  tests  Repeated  loads  Cyclic  loads Résumé : This study examines the effectiveness of a prefabricated vertical drain (PVD) installed in reconstituted soft clay, where a large cyclic triaxial device was used to simulate repeated loading representing a rail track environment. The experimental data demonstrate that PVD successfully prevents excessive buildup of pore water pressure during cyclic loading, and that dissipation continues to occur after the load is removed. The findings of this study have direct relevance to rail track environments, e.g., in coastal Australia, where PVD installation beneath rail tracks constructed on low-lying estuarine soils has been recently introduced. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000006

Oedometer behavior of an artificial cemented highly collapsible soil / G. M. Medero in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 6 (Juin 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 840–843 Titre : Oedometer behavior of an artificial cemented highly collapsible soil Type de document : texte imprimé Auteurs : G. M. Medero, Auteur ; F. Schnaid, Auteur ; W. Y. Gehling, Auteur Année de publication : 2009 Article en page(s) : pp. 840–843 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Collapsible  soils  Cements  Unsaturated  soils  Laboratory  tests Résumé : This study aims at investigating the mechanical behavior and the changes in fabric at various stages of loading and wetting of an artificial cemented highly collapsible geomaterial. The required metastable structure of a collapsible soil was produced by adding particles of expanded polystyrene to a soil-cement mixture. This technique is shown to reproduce main features inherently attributed to collapsible soils under idealized conditions where the effects of void ratio and degree of cementation can be properly isolated and accounted for. Collapse potential was evaluated on samples with and without cementation. From the observed behavior it was possible to identify the initial void ratio, cementation level, initial suction, and stress path as factors controlling the collapse potential of soils. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A6%2884 [...] [article] Oedometer behavior of an artificial cemented highly collapsible soil [texte imprimé] / G. M. Medero, Auteur ; F. Schnaid, Auteur ; W. Y. Gehling, Auteur . - 2009 . - pp. 840–843. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 6 (Juin 2009) . - pp. 840–843 Mots-clés : Collapsible  soils  Cements  Unsaturated  soils  Laboratory  tests Résumé : This study aims at investigating the mechanical behavior and the changes in fabric at various stages of loading and wetting of an artificial cemented highly collapsible geomaterial. The required metastable structure of a collapsible soil was produced by adding particles of expanded polystyrene to a soil-cement mixture. This technique is shown to reproduce main features inherently attributed to collapsible soils under idealized conditions where the effects of void ratio and degree of cementation can be properly isolated and accounted for. Collapse potential was evaluated on samples with and without cementation. From the observed behavior it was possible to identify the initial void ratio, cementation level, initial suction, and stress path as factors controlling the collapse potential of soils. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A6%2884 [...]

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