Dépouillements

Chemical compatibility of model soil-bentonite backfill containing multiswellable bentonite / Michael A. Malusis in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 189-198 Titre : Chemical compatibility of model soil-bentonite backfill containing multiswellable bentonite Type de document : texte imprimé Auteurs : Michael A. Malusis, Auteur ; Matthew D. McKeehan, Auteur Année de publication : 2013 Article en page(s) : pp. 189-198 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : backfill;  bentonite;  chemical  compatibility;  cutoff  wall;  hydraulic  conductivity;  vertical  barrier Résumé : The objective of this study was to evaluate the chemical compatibility of model soil-bentonite backfills containing multiswellable bentonite (MSB) relative to that of similar backfills containing untreated sodium (Na) bentonite or a commercially available, contaminant-resistant bentonite (SW101). Flexible-wall tests were conducted on consolidated backfill specimens (effective stress=34.5 kPa) containing clean sand and 4.5–5.7% bentonite (by dry weight) using tap water and calcium chloride (CaCl2) solutions (10–1,000 mM) as the permeant liquids. Final values of hydraulic conductivity (k) and intrinsic permeability (K) to the CaCl2 solutions were determined after achieving both short-term termination criteria as defined by ASTM D5084 and long-term termination criteria for chemical equilibrium between the influent and effluent. Specimens containing MSB exhibited the smallest increases in k and K upon permeation with a given CaCl2 solution relative to specimens containing untreated Na bentonite or SW101. However, none of the specimens exhibited more than a fivefold increase in k or K, regardless of CaCl2 concentration or bentonite type. Final k values for specimens permeated with a given CaCl2 solution after permeation with tap water were similar to those for specimens of the same backfill permeated with only the CaCl2 solution, indicating that the order of permeation had no significant effect on k. Also, final k values for all specimens were within a factor of two of the k measured after achieving the ASTM D5084 termination criteria. Thus, use of only the ASTM D5084 criteria would have been sufficient to obtain reasonable estimates of long-term hydraulic conductivity for the specimens in this study. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000729 [article] Chemical compatibility of model soil-bentonite backfill containing multiswellable bentonite [texte imprimé] / Michael A. Malusis, Auteur ; Matthew D. McKeehan, Auteur . - 2013 . - pp. 189-198. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 189-198 Mots-clés : backfill;  bentonite;  chemical  compatibility;  cutoff  wall;  hydraulic  conductivity;  vertical  barrier Résumé : The objective of this study was to evaluate the chemical compatibility of model soil-bentonite backfills containing multiswellable bentonite (MSB) relative to that of similar backfills containing untreated sodium (Na) bentonite or a commercially available, contaminant-resistant bentonite (SW101). Flexible-wall tests were conducted on consolidated backfill specimens (effective stress=34.5 kPa) containing clean sand and 4.5–5.7% bentonite (by dry weight) using tap water and calcium chloride (CaCl2) solutions (10–1,000 mM) as the permeant liquids. Final values of hydraulic conductivity (k) and intrinsic permeability (K) to the CaCl2 solutions were determined after achieving both short-term termination criteria as defined by ASTM D5084 and long-term termination criteria for chemical equilibrium between the influent and effluent. Specimens containing MSB exhibited the smallest increases in k and K upon permeation with a given CaCl2 solution relative to specimens containing untreated Na bentonite or SW101. However, none of the specimens exhibited more than a fivefold increase in k or K, regardless of CaCl2 concentration or bentonite type. Final k values for specimens permeated with a given CaCl2 solution after permeation with tap water were similar to those for specimens of the same backfill permeated with only the CaCl2 solution, indicating that the order of permeation had no significant effect on k. Also, final k values for all specimens were within a factor of two of the k measured after achieving the ASTM D5084 termination criteria. Thus, use of only the ASTM D5084 criteria would have been sufficient to obtain reasonable estimates of long-term hydraulic conductivity for the specimens in this study. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000729

Pile setup in cohesive soil / Kam W. Ng in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 199-209 Titre : Pile setup in cohesive soil : I: experimental investigation Type de document : texte imprimé Auteurs : Kam W. Ng, Auteur ; Matthew Roling, Auteur ; Sherif S. AbdelSalam, Auteur Année de publication : 2013 Article en page(s) : pp. 199-209 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : pile  setup;  load  tests;  cohesive  soil;  coefficient  of  consolidation;  undrained  shear  strength;  standard  penetration  test  (SPT)  N-value Résumé : Pile setup in cohesive soils has been a known phenomenon for several decades. However, a systematic field investigation to provide the needed data to develop analytical procedures and integrate pile setup into the design method rarely exists. This paper summarizes a recently completed field investigation on five fully instrumented steel H-piles embedded in cohesive soils, while a companion paper discusses the development of the pile setup method. During the field investigation, detailed soil characterization, monitoring of soil total lateral stress and pore-water pressure, collection of pile dynamic restrike data as a function of time, and vertical static load tests were completed. Restrike measurements confirm that pile setup occurs at a logarithmic rate following the end of driving, and its development correlates well with the rate of dissipation of the measured pore-water pressure. Based on the field data collected, it was concluded that the skin friction component, not the end bearing, contributes predominantly to the setup, which can be accurately estimated for practical purposes using soil properties, such as coefficient of consolidation, undrained shear strength, and the standard penetration test N-value. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000751 [article] Pile setup in cohesive soil : I: experimental investigation [texte imprimé] / Kam W. Ng, Auteur ; Matthew Roling, Auteur ; Sherif S. AbdelSalam, Auteur . - 2013 . - pp. 199-209. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 199-209 Mots-clés : pile  setup;  load  tests;  cohesive  soil;  coefficient  of  consolidation;  undrained  shear  strength;  standard  penetration  test  (SPT)  N-value Résumé : Pile setup in cohesive soils has been a known phenomenon for several decades. However, a systematic field investigation to provide the needed data to develop analytical procedures and integrate pile setup into the design method rarely exists. This paper summarizes a recently completed field investigation on five fully instrumented steel H-piles embedded in cohesive soils, while a companion paper discusses the development of the pile setup method. During the field investigation, detailed soil characterization, monitoring of soil total lateral stress and pore-water pressure, collection of pile dynamic restrike data as a function of time, and vertical static load tests were completed. Restrike measurements confirm that pile setup occurs at a logarithmic rate following the end of driving, and its development correlates well with the rate of dissipation of the measured pore-water pressure. Based on the field data collected, it was concluded that the skin friction component, not the end bearing, contributes predominantly to the setup, which can be accurately estimated for practical purposes using soil properties, such as coefficient of consolidation, undrained shear strength, and the standard penetration test N-value. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000751

Pile setup in cohesive soil / Kam W. Ng in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 210-222 Titre : Pile setup in cohesive soil : II: analytical quantifications and design recommendations Type de document : texte imprimé Auteurs : Kam W. Ng, Auteur ; Muhannad T. Suleiman, Auteur ; Sritharan, Sri, Auteur Année de publication : 2013 Article en page(s) : pp. 210-222 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : pile  setup;  undrained  shear  strength;  SPT;  coefficient  of  consolidation;  restrikes;  static  load  test Résumé : This paper establishes a methodology to quantify pile setup by using recent field test data that was presented in a companion paper for steel H-piles driven in cohesive soils. Existing methods found in literature for the same purpose either require restrikes of piles onsite or are developed for a specific soil type and seldom use easily quantifiable soil properties, despite their significant influence on pile setup. Following a critical evaluation of the existing methods, a new approach for estimating pile setup was developed using dynamic measurements and analyses in combination with measured soil properties, such as the horizontal coefficient of consolidation, undrained shear strength, and the standard penetration test N value. Using pile setup information available in the literature, the proposed approach has shown that it provides good estimates for the setup of steel H-piles, as well as for other types and sizes of driven piles. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000753 [article] Pile setup in cohesive soil : II: analytical quantifications and design recommendations [texte imprimé] / Kam W. Ng, Auteur ; Muhannad T. Suleiman, Auteur ; Sritharan, Sri, Auteur . - 2013 . - pp. 210-222. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 210-222 Mots-clés : pile  setup;  undrained  shear  strength;  SPT;  coefficient  of  consolidation;  restrikes;  static  load  test Résumé : This paper establishes a methodology to quantify pile setup by using recent field test data that was presented in a companion paper for steel H-piles driven in cohesive soils. Existing methods found in literature for the same purpose either require restrikes of piles onsite or are developed for a specific soil type and seldom use easily quantifiable soil properties, despite their significant influence on pile setup. Following a critical evaluation of the existing methods, a new approach for estimating pile setup was developed using dynamic measurements and analyses in combination with measured soil properties, such as the horizontal coefficient of consolidation, undrained shear strength, and the standard penetration test N value. Using pile setup information available in the literature, the proposed approach has shown that it provides good estimates for the setup of steel H-piles, as well as for other types and sizes of driven piles. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000753

Pile-group response to large soil displacements and liquefaction / Panagiota Tasiopoulou in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 223-233 Titre : Pile-group response to large soil displacements and liquefaction : centrifuge experiments versus a physically simplified analysis Type de document : texte imprimé Auteurs : Panagiota Tasiopoulou, Auteur ; Nikos Gerolymos, Auteur ; Takashi Tazoh, Auteur Année de publication : 2013 Article en page(s) : pp. 223-233 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : lateral  spreading;  pile;  quay  wall;  liquefaction;  sheet-pile  wall;  soil-structure  interaction Résumé : The paper presents a physically simplified method for computing displacements and structural forces on piles under conditions of lateral spreading triggered by the large seaward displacement of a harbor quay wall. The method avoids the empirical selection of stiffness-reduction factors and the associated use of p-y curves that current state-of-the-art methods use. Instead, the three-dimensional (3D) highly nonlinear problem is approximated in two steps, both involving two-dimensional (2D) plane-strain analyses. The first step involves a vertical (representative) slice in which the pile group has been omitted and that, shaken at its base, gives the permanent deformation of the quay wall and of the liquefiable soil. It is an effective stress analysis. In the second step, a horizontal (representative) slice taken from the middle of the liquefiable zone is subjected to an outward quay wall displacement; the goal is to evaluate the reduction of the pile displacement over the free-field one and the ensuing pile group distress. The pile resistance to ground deformation depends heavily on the constraints imposed by the superstructure, as well on the exact stiffness of the soil layers. Thus, the interplay between soil piles-quay wall under soil flow conditions is captured in a physically meaningful way. The predictions compare well with results from two centrifuge tests. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000759 [article] Pile-group response to large soil displacements and liquefaction : centrifuge experiments versus a physically simplified analysis [texte imprimé] / Panagiota Tasiopoulou, Auteur ; Nikos Gerolymos, Auteur ; Takashi Tazoh, Auteur . - 2013 . - pp. 223-233. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 223-233 Mots-clés : lateral  spreading;  pile;  quay  wall;  liquefaction;  sheet-pile  wall;  soil-structure  interaction Résumé : The paper presents a physically simplified method for computing displacements and structural forces on piles under conditions of lateral spreading triggered by the large seaward displacement of a harbor quay wall. The method avoids the empirical selection of stiffness-reduction factors and the associated use of p-y curves that current state-of-the-art methods use. Instead, the three-dimensional (3D) highly nonlinear problem is approximated in two steps, both involving two-dimensional (2D) plane-strain analyses. The first step involves a vertical (representative) slice in which the pile group has been omitted and that, shaken at its base, gives the permanent deformation of the quay wall and of the liquefiable soil. It is an effective stress analysis. In the second step, a horizontal (representative) slice taken from the middle of the liquefiable zone is subjected to an outward quay wall displacement; the goal is to evaluate the reduction of the pile displacement over the free-field one and the ensuing pile group distress. The pile resistance to ground deformation depends heavily on the constraints imposed by the superstructure, as well on the exact stiffness of the soil layers. Thus, the interplay between soil piles-quay wall under soil flow conditions is captured in a physically meaningful way. The predictions compare well with results from two centrifuge tests. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000759

Simple model for nonlinear response of 52 laterally loaded piles / Wei Dong Guo in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 234-252 Titre : Simple model for nonlinear response of 52 laterally loaded piles Type de document : texte imprimé Auteurs : Wei Dong Guo, Auteur Année de publication : 2013 Article en page(s) : pp. 234-252 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : modulus;  parameters;  nonlinear  response;  limiting  force  profiles;  lateral  loading;  piles Résumé : The response of a laterally loaded pile is normally dominated by the limiting force per unit length profile (LFP, pu) mobilized along the pile to the depth of the plastic zone (e.g., maximum slip depth, max xp) and depends on pile-soil relative rigidity (via the subgrade modulus of elasticity k). The values of pu and the shear modulus (G, thus k) were deduced extensively against the measured response of 32 and 20 piles tested in situ in clay and sand, respectively. In this paper, simplified closed-form solutions are presented for the design of laterally loaded piles. The parameters of the pu and the G obtained previously are utilized to examine the impact of loading eccentricity on piles and to assess the validity of existing pu-profiles. Expressions are also explored and provided regarding determinations of the pu-profiles, the modulus of the subgrade reaction k (via G), the ranges of the plastic zone (max xp), and the depth of elastic influence (via the critical pile length Lcr), along with the correlations between the shear modulus of soil G and undrained shear strength (su) and/or the standard penetration test blow count (N). It is noted that the popularly adopted LFPs (such as Matlock’s LFP, Reese’s LFP, and American Petroleum Institute code methods) are not sufficiently accurate for 60–85% of the 52 piles investigated herein, especially for those with a diameter >1.5 m. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000726 [article] Simple model for nonlinear response of 52 laterally loaded piles [texte imprimé] / Wei Dong Guo, Auteur . - 2013 . - pp. 234-252. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 234-252 Mots-clés : modulus;  parameters;  nonlinear  response;  limiting  force  profiles;  lateral  loading;  piles Résumé : The response of a laterally loaded pile is normally dominated by the limiting force per unit length profile (LFP, pu) mobilized along the pile to the depth of the plastic zone (e.g., maximum slip depth, max xp) and depends on pile-soil relative rigidity (via the subgrade modulus of elasticity k). The values of pu and the shear modulus (G, thus k) were deduced extensively against the measured response of 32 and 20 piles tested in situ in clay and sand, respectively. In this paper, simplified closed-form solutions are presented for the design of laterally loaded piles. The parameters of the pu and the G obtained previously are utilized to examine the impact of loading eccentricity on piles and to assess the validity of existing pu-profiles. Expressions are also explored and provided regarding determinations of the pu-profiles, the modulus of the subgrade reaction k (via G), the ranges of the plastic zone (max xp), and the depth of elastic influence (via the critical pile length Lcr), along with the correlations between the shear modulus of soil G and undrained shear strength (su) and/or the standard penetration test blow count (N). It is noted that the popularly adopted LFPs (such as Matlock’s LFP, Reese’s LFP, and American Petroleum Institute code methods) are not sufficiently accurate for 60–85% of the 52 piles investigated herein, especially for those with a diameter >1.5 m. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000726

Shaft capacity of displacement piles in clay using the cone penetration test / Barry M. Lehane in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 253-266 Titre : Shaft capacity of displacement piles in clay using the cone penetration test Type de document : texte imprimé Auteurs : Barry M. Lehane, Auteur ; Yunong Li, Auteur ; Ryan Williams, Auteur Année de publication : 2013 Article en page(s) : pp. 253-266 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : shafts;  friction;  displacement;  piles;  clays Résumé : The prediction of the shaft capacity of displacement piles in clay still relies wholly on empirical or semiempirical approaches. This paper examines the predictive abilities of five well-known methods against an extended version of an existing database of pile tests. It is seen that coefficients of variation (COVs) of the ratio of calculated to measured capacities (Qc/Qm) are significantly higher than expected. The paper then uses the database of shaft capacities to examine potential relationships between local shaft friction and the cone penetration test end resistance (qt). Predictions are subsequently compared with capacities measured in a series of centrifuge tests and with the distributions of peak frictions observed in two well-documented field tests. Widely different formulations adopted by each of the existing empirical methods give broadly similar COV values for Qc/Qm ratios, and it is concluded that the database of high-quality pile tests needs to be expanded significantly if the reliability of estimates of shaft capacity in clay is to be improved. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000749 [article] Shaft capacity of displacement piles in clay using the cone penetration test [texte imprimé] / Barry M. Lehane, Auteur ; Yunong Li, Auteur ; Ryan Williams, Auteur . - 2013 . - pp. 253-266. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 253-266 Mots-clés : shafts;  friction;  displacement;  piles;  clays Résumé : The prediction of the shaft capacity of displacement piles in clay still relies wholly on empirical or semiempirical approaches. This paper examines the predictive abilities of five well-known methods against an extended version of an existing database of pile tests. It is seen that coefficients of variation (COVs) of the ratio of calculated to measured capacities (Qc/Qm) are significantly higher than expected. The paper then uses the database of shaft capacities to examine potential relationships between local shaft friction and the cone penetration test end resistance (qt). Predictions are subsequently compared with capacities measured in a series of centrifuge tests and with the distributions of peak frictions observed in two well-documented field tests. Widely different formulations adopted by each of the existing empirical methods give broadly similar COV values for Qc/Qm ratios, and it is concluded that the database of high-quality pile tests needs to be expanded significantly if the reliability of estimates of shaft capacity in clay is to be improved. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000749

Bayesian approach for probabilistic site characterization using cone penetration tests / Zijun Cao in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 267-276 Titre : Bayesian approach for probabilistic site characterization using cone penetration tests Type de document : texte imprimé Auteurs : Zijun Cao, Auteur ; Yu Wang, Auteur Année de publication : 2013 Article en page(s) : pp. 267-276 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : Bayesian  system  identification;  Bayesian  model  class  selection;  prior  knowledge;  spatial  variability;  statistically  homogenous  layer;  random  field Résumé : This paper develops a Bayesian approach for probabilistic site characterization (i.e., on both stratigraphy and soil properties) using cone penetration tests (CPTs). The available site information prior to the project (e.g., existing geological maps, geotechnical reports, and local experience) is used in the Bayesian approach as prior knowledge, and it is integrated systematically with results of CPTs that are performed deliberately for the project. The inherent spatial variability of soil is modeled explicitly by random field theory. The proposed approach contains two major components: a Bayesian model class selection method to identify the most probable number of statistically homogenous layers of soil and a Bayesian system identification method to estimate the most probable layer thicknesses and soil properties probabilistically. Equations are derived for the Bayesian approach, and the proposed approach is illustrated using a set of real CPT data obtained from a site in Netherlands. It has been shown that the proposed approach correctly identifies the number and thicknesses/boundaries of the statistically homogenous layers of soil and provides proper probabilistic characterization of soil properties. The Bayesian approach provides a means to identify the statistically homogenous layers progressively by gradually zooming into local differences with improved resolution, and it also contains a mechanism to determine when to stop such zooming. In addition, a sensitivity study is performed to explore the effect of prior knowledge. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000765 [article] Bayesian approach for probabilistic site characterization using cone penetration tests [texte imprimé] / Zijun Cao, Auteur ; Yu Wang, Auteur . - 2013 . - pp. 267-276. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 267-276 Mots-clés : Bayesian  system  identification;  Bayesian  model  class  selection;  prior  knowledge;  spatial  variability;  statistically  homogenous  layer;  random  field Résumé : This paper develops a Bayesian approach for probabilistic site characterization (i.e., on both stratigraphy and soil properties) using cone penetration tests (CPTs). The available site information prior to the project (e.g., existing geological maps, geotechnical reports, and local experience) is used in the Bayesian approach as prior knowledge, and it is integrated systematically with results of CPTs that are performed deliberately for the project. The inherent spatial variability of soil is modeled explicitly by random field theory. The proposed approach contains two major components: a Bayesian model class selection method to identify the most probable number of statistically homogenous layers of soil and a Bayesian system identification method to estimate the most probable layer thicknesses and soil properties probabilistically. Equations are derived for the Bayesian approach, and the proposed approach is illustrated using a set of real CPT data obtained from a site in Netherlands. It has been shown that the proposed approach correctly identifies the number and thicknesses/boundaries of the statistically homogenous layers of soil and provides proper probabilistic characterization of soil properties. The Bayesian approach provides a means to identify the statistically homogenous layers progressively by gradually zooming into local differences with improved resolution, and it also contains a mechanism to determine when to stop such zooming. In addition, a sensitivity study is performed to explore the effect of prior knowledge. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000765

Correcting liquefaction resistance of unsaturated soil using wave velocity / Akhter M. Hossain in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 277-287 Titre : Correcting liquefaction resistance of unsaturated soil using wave velocity Type de document : texte imprimé Auteurs : Akhter M. Hossain, Auteur ; Ronald D. Andrus, Auteur ; William M. CampIII, Auteur Année de publication : 2013 Article en page(s) : pp. 277-287 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : compression;  wave  velocity;  soil  liquefaction;  penetration  tests;  shear  waves;  unsaturated  soils Résumé : Explicit empirical relationships for correcting liquefaction resistance of unsaturated soil below the groundwater table using compression wave velocity (VP) and shear wave velocity (VS) are derived and evaluated in this paper. The relationships are derived using published laboratory test data for four different sands and one silt material. The laboratory test data based on VP exhibit less scatter than the test data based on the ratio VP/VS. For this reason, the VP-based relationship is recommended for correcting the liquefaction resistance of unsaturated soil. The influence of loading cycles and relative density on the recommended relationship is investigated. From a review of 40 field case history sites, it is found that in the critical layers at 20% of the sites, average VP is less than 1,400 m/s, indicating unsaturated conditions. Liquefaction resistances computed for eight field case histories with VP<1,200 m/s in the critical layers are corrected and plotted on penetration- and VS-based liquefaction evaluation charts. The results support the use of the correction for unsaturated conditions below the groundwater table. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000770 [article] Correcting liquefaction resistance of unsaturated soil using wave velocity [texte imprimé] / Akhter M. Hossain, Auteur ; Ronald D. Andrus, Auteur ; William M. CampIII, Auteur . - 2013 . - pp. 277-287. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 277-287 Mots-clés : compression;  wave  velocity;  soil  liquefaction;  penetration  tests;  shear  waves;  unsaturated  soils Résumé : Explicit empirical relationships for correcting liquefaction resistance of unsaturated soil below the groundwater table using compression wave velocity (VP) and shear wave velocity (VS) are derived and evaluated in this paper. The relationships are derived using published laboratory test data for four different sands and one silt material. The laboratory test data based on VP exhibit less scatter than the test data based on the ratio VP/VS. For this reason, the VP-based relationship is recommended for correcting the liquefaction resistance of unsaturated soil. The influence of loading cycles and relative density on the recommended relationship is investigated. From a review of 40 field case history sites, it is found that in the critical layers at 20% of the sites, average VP is less than 1,400 m/s, indicating unsaturated conditions. Liquefaction resistances computed for eight field case histories with VP<1,200 m/s in the critical layers are corrected and plotted on penetration- and VS-based liquefaction evaluation charts. The results support the use of the correction for unsaturated conditions below the groundwater table. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000770

Probabilistic seismic hazard analysis for maximum seismic shear stresses in soils using improved ground-motion parameters / Tadahiro Kishida in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 288-297 Titre : Probabilistic seismic hazard analysis for maximum seismic shear stresses in soils using improved ground-motion parameters Type de document : texte imprimé Auteurs : Tadahiro Kishida, Auteur ; Chi-Chin Tsai, Auteur Année de publication : 2013 Article en page(s) : pp. 288-297 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : seismic  design;  shear  stress;  ground  motion;  probability;  hazards;  soil  strength Résumé : Maximum seismic shear stresses (τmax) have been recognized as one of the important parameters in design practice. This study develops ground-motion parameters for τmax and implements these in probabilistic seismic hazard analysis to provide the τmax distribution of deep soil layers for design purposes. The application of improved ground-motion parameters for τmax is demonstrated at the Oakland International Airport, where a thick Young Bay Mud deposit exists under the artificial fill. Model biases in the predictive equations of seismic shear-stress reduction coefficients (rd) are evaluated by comparison with the site response analyses performed with a wide range of input ground motions. Based on these results, we introduce improved ground-motion parameters for τmax (Itau) as a linear combination of spectral accelerations, implemented in probabilistic seismic hazard analysis to calculate seismic hazard curves. Conditional mean spectra are calculated, given Itau at 10% in 50 years to illustrate the variations in frequency contents with depth compared with the uniform hazard spectra. Finally, τmax is calculated with depth by using hazard values of Itau and compared with the peak-ground-acceleration-based and uniform-hazard-spectra-based calculations. Analysis results show that τmax will be underestimated for deep soil layers by peak-ground-acceleration-based calculation if the median value of rd is used in design practice. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000740 [article] Probabilistic seismic hazard analysis for maximum seismic shear stresses in soils using improved ground-motion parameters [texte imprimé] / Tadahiro Kishida, Auteur ; Chi-Chin Tsai, Auteur . - 2013 . - pp. 288-297. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 288-297 Mots-clés : seismic  design;  shear  stress;  ground  motion;  probability;  hazards;  soil  strength Résumé : Maximum seismic shear stresses (τmax) have been recognized as one of the important parameters in design practice. This study develops ground-motion parameters for τmax and implements these in probabilistic seismic hazard analysis to provide the τmax distribution of deep soil layers for design purposes. The application of improved ground-motion parameters for τmax is demonstrated at the Oakland International Airport, where a thick Young Bay Mud deposit exists under the artificial fill. Model biases in the predictive equations of seismic shear-stress reduction coefficients (rd) are evaluated by comparison with the site response analyses performed with a wide range of input ground motions. Based on these results, we introduce improved ground-motion parameters for τmax (Itau) as a linear combination of spectral accelerations, implemented in probabilistic seismic hazard analysis to calculate seismic hazard curves. Conditional mean spectra are calculated, given Itau at 10% in 50 years to illustrate the variations in frequency contents with depth compared with the uniform hazard spectra. Finally, τmax is calculated with depth by using hazard values of Itau and compared with the peak-ground-acceleration-based and uniform-hazard-spectra-based calculations. Analysis results show that τmax will be underestimated for deep soil layers by peak-ground-acceleration-based calculation if the median value of rd is used in design practice. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000740

Nongrouted ratio evaluation of rock bolts by reflection of guided ultrasonic waves / Jung-Doung Yu in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 298-307 Titre : Nongrouted ratio evaluation of rock bolts by reflection of guided ultrasonic waves Type de document : texte imprimé Auteurs : Jung-Doung Yu, Auteur ; Myeong-Ho Bae, Auteur ; In-Mo Lee, Auteur Année de publication : 2013 Article en page(s) : pp. 298-307 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : ultrasonic  methods;  rock  masses;  bolts;  wavelet Résumé : The objective of this study is to develop and apply reflection methods for guided ultrasonic waves used in evaluating the grout condition of rock bolts installed in a rock mass. Three types of rock bolts with different grouting ratios are prepared. First, piezoelectric disk elements are used as the source of guided ultrasonic waves to investigate grouted nonembedded rock bolts. Second, reflection methods with piezo disk elements and hammer impacts are used with rock bolts embedded in concrete columns. Third, a hammer impact with a center punch is applied for investigating rock bolts embedded in a rock mass in the field. The measured guided waves were analyzed using wavelet transforms. The peak magnitudes of the wavelet transform are used for group velocity calculations. Although piezo disk elements are sufficient as sources for nonembedded rock bolts and rock bolts installed in concrete columns, they do not provide sufficient energy in the field. However, a hammer impact with a center punch can generate guided ultrasonic waves with enough energy to evaluate the nongrouted ratio in rock bolts embedded in a rock mass. The group velocities of the guided ultrasonic waves increase with increasing nongrouted ratio. This study demonstrates that the suggested hammer impact method is effective for evaluating the nongrouted ratio of rock bolts in the field. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000767 [article] Nongrouted ratio evaluation of rock bolts by reflection of guided ultrasonic waves [texte imprimé] / Jung-Doung Yu, Auteur ; Myeong-Ho Bae, Auteur ; In-Mo Lee, Auteur . - 2013 . - pp. 298-307. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 298-307 Mots-clés : ultrasonic  methods;  rock  masses;  bolts;  wavelet Résumé : The objective of this study is to develop and apply reflection methods for guided ultrasonic waves used in evaluating the grout condition of rock bolts installed in a rock mass. Three types of rock bolts with different grouting ratios are prepared. First, piezoelectric disk elements are used as the source of guided ultrasonic waves to investigate grouted nonembedded rock bolts. Second, reflection methods with piezo disk elements and hammer impacts are used with rock bolts embedded in concrete columns. Third, a hammer impact with a center punch is applied for investigating rock bolts embedded in a rock mass in the field. The measured guided waves were analyzed using wavelet transforms. The peak magnitudes of the wavelet transform are used for group velocity calculations. Although piezo disk elements are sufficient as sources for nonembedded rock bolts and rock bolts installed in concrete columns, they do not provide sufficient energy in the field. However, a hammer impact with a center punch can generate guided ultrasonic waves with enough energy to evaluate the nongrouted ratio in rock bolts embedded in a rock mass. The group velocities of the guided ultrasonic waves increase with increasing nongrouted ratio. This study demonstrates that the suggested hammer impact method is effective for evaluating the nongrouted ratio of rock bolts in the field. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000767

System reliability of concrete dams with respect to foundation stability / Marie Westberg Wilde in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 308-319 Titre : System reliability of concrete dams with respect to foundation stability : application to a spillway Type de document : texte imprimé Auteurs : Marie Westberg Wilde, Auteur ; Fredrik Johansson, Auteur Année de publication : 2013 Article en page(s) : pp. 308-319 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : system  reliability;  dam  safety;  dam  foundations;  structural  reliability;  sliding;  cohesion;  concrete  structures;  spillways;  concrete  dams;  failure  modes Résumé : Structural reliability analysis is not widely used for the design and assessment of concrete dams. In this paper, the system reliability of a spillway structure consisting of two monoliths is calculated. Limit state functions are defined from the failure modes sliding in the concrete rock contact, sliding in the rock mass, and adjusted overturning. Random variables in the limit state functions are defined by stochastic distributions. These are defined based on site investigations and laboratory tests from samples taken at the dam. Simulations and information from the literature are used for the remaining variables. The safety index is calculated by the first-order reliability method for each failure mode and monolith, and the system reliability is approximated by direct integration of the bivariate normal distribution. The output is the safety index including associated sensitivity values at the single failure mode, monolith, and system levels. The results show that the system safety is governed by a persistent rock joint beneath one monolith. A system reliability analysis is found to be a useful tool in the dam risk management process as it can be used to calculate the probability of failure and to identify important failure modes and variables. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000761 [article] System reliability of concrete dams with respect to foundation stability : application to a spillway [texte imprimé] / Marie Westberg Wilde, Auteur ; Fredrik Johansson, Auteur . - 2013 . - pp. 308-319. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 308-319 Mots-clés : system  reliability;  dam  safety;  dam  foundations;  structural  reliability;  sliding;  cohesion;  concrete  structures;  spillways;  concrete  dams;  failure  modes Résumé : Structural reliability analysis is not widely used for the design and assessment of concrete dams. In this paper, the system reliability of a spillway structure consisting of two monoliths is calculated. Limit state functions are defined from the failure modes sliding in the concrete rock contact, sliding in the rock mass, and adjusted overturning. Random variables in the limit state functions are defined by stochastic distributions. These are defined based on site investigations and laboratory tests from samples taken at the dam. Simulations and information from the literature are used for the remaining variables. The safety index is calculated by the first-order reliability method for each failure mode and monolith, and the system reliability is approximated by direct integration of the bivariate normal distribution. The output is the safety index including associated sensitivity values at the single failure mode, monolith, and system levels. The results show that the system safety is governed by a persistent rock joint beneath one monolith. A system reliability analysis is found to be a useful tool in the dam risk management process as it can be used to calculate the probability of failure and to identify important failure modes and variables. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000761

Probabilistic porous model to simulate the retention curve of soils / Eduardo Rojas in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 320-329 Titre : Probabilistic porous model to simulate the retention curve of soils Type de document : texte imprimé Auteurs : Eduardo Rojas, Auteur ; Jaime Horta, Auteur ; Teresa López-Lara, Auteur Année de publication : 2013 Article en page(s) : pp. 320-329 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : porous  media;  stochastic  models;  soil  suction;  pore  size  distribution;  unsaturated  soils Résumé : A probabilistic porous model is used to simulate the retention curves of different types of soils. The model is based on the same principles of porous networks models; however, it shows important advantages over them. It considers two different elements: the sites and the bonds. It is able to simulate the retention curves of a material when its pore size distribution is known. It can also be used to interpret more realistically the results of mercury intrusion porosimetry tests. In this paper, the model is used to obtain the pore size distribution of different soils using the retention curve as its data source. The comparison between numerical and experimental results for different soils shows that the model approximately reproduces the pore size distribution obtained from mercury intrusion porosimetry tests. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000763 [article] Probabilistic porous model to simulate the retention curve of soils [texte imprimé] / Eduardo Rojas, Auteur ; Jaime Horta, Auteur ; Teresa López-Lara, Auteur . - 2013 . - pp. 320-329. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 320-329 Mots-clés : porous  media;  stochastic  models;  soil  suction;  pore  size  distribution;  unsaturated  soils Résumé : A probabilistic porous model is used to simulate the retention curves of different types of soils. The model is based on the same principles of porous networks models; however, it shows important advantages over them. It considers two different elements: the sites and the bonds. It is able to simulate the retention curves of a material when its pore size distribution is known. It can also be used to interpret more realistically the results of mercury intrusion porosimetry tests. In this paper, the model is used to obtain the pore size distribution of different soils using the retention curve as its data source. The comparison between numerical and experimental results for different soils shows that the model approximately reproduces the pore size distribution obtained from mercury intrusion porosimetry tests. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000763

Improvement of hole erosion test and results on reference soils / Iman Haghighi in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 330-339 Titre : Improvement of hole erosion test and results on reference soils Type de document : texte imprimé Auteurs : Iman Haghighi, Auteur ; Chevalier, Christophe, Auteur ; Myriam Duc, Auteur Année de publication : 2013 Article en page(s) : pp. 330-339 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : soil  erosion;  levees  and  dikes;  laboratory  tests;  shear  stress;  suspended  solids;  holes Résumé : Understanding the factors that control the transport of soil particles detached by water is essential in predicting the contingency of internal and surface erosion of embankments during storms and floods. It is particularly useful to be able to evaluate the sensitivity of the available soils to erosion at an early stage of a project and the risk assessment of an existing earthwork. The presented study is based on laboratory tests with a hole erosion test apparatus and tries to characterize the internal erosion of soils. The test consists of eroding a drilled soil specimen by water flow with a constant pressure drop at the boundaries of the specimen while recording the flow rate and studying the hole enlargement. A new version of the apparatus with improved instruments and an interpretation method is proposed, estimating the erosion rate based on the turbidity of the outflow and independent of hydraulic charge. Several remolded kaolinite-sand mixtures are tested as reference soil textures, and the results are analyzed with the proposed and existing interpretation methods. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000747 [article] Improvement of hole erosion test and results on reference soils [texte imprimé] / Iman Haghighi, Auteur ; Chevalier, Christophe, Auteur ; Myriam Duc, Auteur . - 2013 . - pp. 330-339. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 330-339 Mots-clés : soil  erosion;  levees  and  dikes;  laboratory  tests;  shear  stress;  suspended  solids;  holes Résumé : Understanding the factors that control the transport of soil particles detached by water is essential in predicting the contingency of internal and surface erosion of embankments during storms and floods. It is particularly useful to be able to evaluate the sensitivity of the available soils to erosion at an early stage of a project and the risk assessment of an existing earthwork. The presented study is based on laboratory tests with a hole erosion test apparatus and tries to characterize the internal erosion of soils. The test consists of eroding a drilled soil specimen by water flow with a constant pressure drop at the boundaries of the specimen while recording the flow rate and studying the hole enlargement. A new version of the apparatus with improved instruments and an interpretation method is proposed, estimating the erosion rate based on the turbidity of the outflow and independent of hydraulic charge. Several remolded kaolinite-sand mixtures are tested as reference soil textures, and the results are analyzed with the proposed and existing interpretation methods. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000747

Effects of geocell confinement on strength and deformation behavior of gravel / Ben Leshchinsky in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 340-352 Titre : Effects of geocell confinement on strength and deformation behavior of gravel Type de document : texte imprimé Auteurs : Ben Leshchinsky, Auteur ; Ling, Hoe, Auteur Année de publication : 2013 Article en page(s) : pp. 340-352 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : gravel;  railroad  tracks;  confinement;  deformation;  laboratory  tests;  finite  element  method;  parameters Résumé : In past years, railroad transportation has been of growing interest because of its efficiency and advancement in railway technologies. However, many issues arise because of the variability in subsurface conditions along the sizeable lengths of track that exist. One very important issue is the need for significant upkeep and maintenance for railways passing over areas of poor soil conditions as a result of continuous deformation and a lack of stiffness from the foundation. One general solution for lack of substructure integrity has been confinement, applied through a variety of reinforcement types, including geocell. To investigate the effectiveness of geocell confinement on substructure integrity, a series of embankment model tests with different configurations of geocell placement (one layer and two layers of geocell) were constructed and loaded monotonically and cyclically for comparison with unreinforced, control tests. On the completion of these tests, the model embankments were simulated numerically using finite-element procedures. The results, which matched reasonably well, were then used as validation for a parametric study, observing the effects of less competent geocell material, gravel, and foundation conditions and their implications. The tests and numerical simulations demonstrate that geocell confinement effectively increased stiffness and strength of a gravel embankment while reducing vertical settlement and lateral spreading. Additionally, the parametric study shows that the use of geocell provides a composite mattressing effect that distributes subgrade stress more uniformly than without reinforcement, increasing bearing capacity and reducing settlement, especially on soft foundations. The results suggested that in some site conditions, use of geocell might be an economical alternative to frequent maintenance and/or lower train speeds. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000757 [article] Effects of geocell confinement on strength and deformation behavior of gravel [texte imprimé] / Ben Leshchinsky, Auteur ; Ling, Hoe, Auteur . - 2013 . - pp. 340-352. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 340-352 Mots-clés : gravel;  railroad  tracks;  confinement;  deformation;  laboratory  tests;  finite  element  method;  parameters Résumé : In past years, railroad transportation has been of growing interest because of its efficiency and advancement in railway technologies. However, many issues arise because of the variability in subsurface conditions along the sizeable lengths of track that exist. One very important issue is the need for significant upkeep and maintenance for railways passing over areas of poor soil conditions as a result of continuous deformation and a lack of stiffness from the foundation. One general solution for lack of substructure integrity has been confinement, applied through a variety of reinforcement types, including geocell. To investigate the effectiveness of geocell confinement on substructure integrity, a series of embankment model tests with different configurations of geocell placement (one layer and two layers of geocell) were constructed and loaded monotonically and cyclically for comparison with unreinforced, control tests. On the completion of these tests, the model embankments were simulated numerically using finite-element procedures. The results, which matched reasonably well, were then used as validation for a parametric study, observing the effects of less competent geocell material, gravel, and foundation conditions and their implications. The tests and numerical simulations demonstrate that geocell confinement effectively increased stiffness and strength of a gravel embankment while reducing vertical settlement and lateral spreading. Additionally, the parametric study shows that the use of geocell provides a composite mattressing effect that distributes subgrade stress more uniformly than without reinforcement, increasing bearing capacity and reducing settlement, especially on soft foundations. The results suggested that in some site conditions, use of geocell might be an economical alternative to frequent maintenance and/or lower train speeds. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000757

Role of particle angularity on the mechanical behavior of granular mixtures / H. Shin in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 2 (Février 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 353-355 Titre : Role of particle angularity on the mechanical behavior of granular mixtures Type de document : texte imprimé Auteurs : H. Shin, Auteur ; J. C. Santamarina, Auteur Année de publication : 2013 Article en page(s) : pp. 353-355 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : particles;  shape;  coefficients;  earth  pressure;  shear  waves;  wave  velocity;  granular  media;  mixtures;  mechanical  properties;  compression Résumé : Particle shape affects the mechanical behavior of soils, including packing density, stiffness, volume change during shear, and strength. Laboratory experiments conducted to study the mechanical response of sand mixtures made of round and angular grains show an increase in void ratio, small strain shear modulus Gmax (constant fabric), oedometric compressibility CC (fabric changes), and friction angle but a decrease in lateral stress coefficient k0 as the mass fraction of angular particles increases. These results reflect variations in particle mobility and highlight the relative role of contact stiffness versus fabric changes. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000768 [article] Role of particle angularity on the mechanical behavior of granular mixtures [texte imprimé] / H. Shin, Auteur ; J. C. Santamarina, Auteur . - 2013 . - pp. 353-355. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 2 (Février 2013) . - pp. 353-355 Mots-clés : particles;  shape;  coefficients;  earth  pressure;  shear  waves;  wave  velocity;  granular  media;  mixtures;  mechanical  properties;  compression Résumé : Particle shape affects the mechanical behavior of soils, including packing density, stiffness, volume change during shear, and strength. Laboratory experiments conducted to study the mechanical response of sand mixtures made of round and angular grains show an increase in void ratio, small strain shear modulus Gmax (constant fabric), oedometric compressibility CC (fabric changes), and friction angle but a decrease in lateral stress coefficient k0 as the mass fraction of angular particles increases. These results reflect variations in particle mobility and highlight the relative role of contact stiffness versus fabric changes. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000768

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