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Influence of clod-size and structure on wetting-induced volume change of compacted soil / Amy B. Cerato in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 11 (Novembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1620–1628 Titre : Influence of clod-size and structure on wetting-induced volume change of compacted soil Type de document : texte imprimé Auteurs : Amy B. Cerato, Auteur ; Gerald A. Miller, Auteur ; Jumanah A. Hajjat, Auteur Année de publication : 2009 Article en page(s) : pp. 1620–1628 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Volume  changeSoil  structureSoil  compactionSoil  water Résumé : Volume changes due to wetting may occur in naturally deposited soils as well as earthen construction (e.g., compacted fills or embankments). Depending on the stress level, some soils exhibit increase in volume upon wetting (swell) while others may exhibit decrease in volume upon wetting (collapse). The work described in this paper focused on wetting-induced volume changes in compacted soils. Motivation for this work stemmed from observations of earthen structures that exhibit problematic behavior under wetting conditions, even though soils were compacted to engineering specifications (i.e., at or above minimum density and within moisture content ranges). Not only is this problematic behavior a concern but also the laboratory tests used to predict settlement of constructed facilities may not properly model the actual behavior of soil compacted under field conditions. For example, settlements experienced by compacted fills may be different from settlement predictions based on one-dimensional oedometer tests. These differences are partly related to the variations in the soil structure in tested specimens that arise because soil clods compacted in the laboratory are smaller than soil clods compacted in the field. The term “soil structure” includes the combined effects of soil fabric and interparticle forces. “Fabric” generally refers to the geometric arrangement of particles, whereas interparticle forces include physical and physicochemical interactions between particles. The soil structure in this case is associated with specimen preparation methods and is influenced by several factors including soil composition (including pore water chemistry), compaction method, clod sizes, initial moisture condition of clods, dry density or void ratio, and compaction moisture content. A laboratory research study was conducted to investigate the influence of variations in clod-size and structure on one-dimensional volume change, with emphasis on wetting-induced volume change, for nine different fine-grained soils. The results of the study suggest that the influence of structure in one-dimensional oedometer tests depends on soil type and nature of the clods in the compacted soil. Clayey soils appear to be influenced more by differences in structure, whereas silts or clayey sands of low plasticity (PI<10) do not appear to suffer as much from structure effects in one-dimensional oedometer tests. This is attributed to more extensive clod development in clayey soils. Furthermore, the moisture condition of clods appears to have an important influence on volume change behavior. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000146 [article] Influence of clod-size and structure on wetting-induced volume change of compacted soil [texte imprimé] / Amy B. Cerato, Auteur ; Gerald A. Miller, Auteur ; Jumanah A. Hajjat, Auteur . - 2009 . - pp. 1620–1628. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 11 (Novembre 2009) . - pp. 1620–1628 Mots-clés : Volume  changeSoil  structureSoil  compactionSoil  water Résumé : Volume changes due to wetting may occur in naturally deposited soils as well as earthen construction (e.g., compacted fills or embankments). Depending on the stress level, some soils exhibit increase in volume upon wetting (swell) while others may exhibit decrease in volume upon wetting (collapse). The work described in this paper focused on wetting-induced volume changes in compacted soils. Motivation for this work stemmed from observations of earthen structures that exhibit problematic behavior under wetting conditions, even though soils were compacted to engineering specifications (i.e., at or above minimum density and within moisture content ranges). Not only is this problematic behavior a concern but also the laboratory tests used to predict settlement of constructed facilities may not properly model the actual behavior of soil compacted under field conditions. For example, settlements experienced by compacted fills may be different from settlement predictions based on one-dimensional oedometer tests. These differences are partly related to the variations in the soil structure in tested specimens that arise because soil clods compacted in the laboratory are smaller than soil clods compacted in the field. The term “soil structure” includes the combined effects of soil fabric and interparticle forces. “Fabric” generally refers to the geometric arrangement of particles, whereas interparticle forces include physical and physicochemical interactions between particles. The soil structure in this case is associated with specimen preparation methods and is influenced by several factors including soil composition (including pore water chemistry), compaction method, clod sizes, initial moisture condition of clods, dry density or void ratio, and compaction moisture content. A laboratory research study was conducted to investigate the influence of variations in clod-size and structure on one-dimensional volume change, with emphasis on wetting-induced volume change, for nine different fine-grained soils. The results of the study suggest that the influence of structure in one-dimensional oedometer tests depends on soil type and nature of the clods in the compacted soil. Clayey soils appear to be influenced more by differences in structure, whereas silts or clayey sands of low plasticity (PI<10) do not appear to suffer as much from structure effects in one-dimensional oedometer tests. This is attributed to more extensive clod development in clayey soils. Furthermore, the moisture condition of clods appears to have an important influence on volume change behavior. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000146

Shear strength of unsaturated soil interfaces / Tariq B. Hamid in Canadian geotechnical journal, Vol. 46 N° 5 (Mai 2009) 

Public ISBD [article]  in Canadian geotechnical journal > Vol. 46 N° 5 (Mai 2009) . - pp. 595-606 Titre : Shear strength of unsaturated soil interfaces Type de document : texte imprimé Auteurs : Tariq B. Hamid, Auteur ; Gerald A. Miller, Auteur Article en page(s) : pp. 595-606 Note générale : Sciences de la Terre Langues : Anglais (eng) Mots-clés : Soil  Unsaturated  Interface  Shear  strength  Sol  non  saturé  Interface  Résistance  au  cisaillement Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : Unsaturated soil interfaces exist where unsaturated soil is in contact with structures such as foundations, retaining walls, and buried pipes. The unsaturated soil interface can be defined as a layer of unsaturated soil through which stresses are transferred from soil to structure and vice versa. In this paper, the shearing behavior of unsaturated soil interfaces is examined using results of interface direct shear tests conducted on a low-plasticity fine-grained soil. A conventional direct shear test device was modified to conduct direct shear interface tests using matric suction control. Further, the results were used to define failure envelopes for unsaturated soil interfaces having smooth and rough counterfaces. Results of this study indicate that matric suction contributes to the peak shear strength of unsaturated interfaces; however, postpeak shear strength did not appear to vary with changes in matric suction. Variations in net normal stress affected both peak and postpeak shear strength. Failure envelopes developed using the soil-water characteristic curve (SWCC) appeared to capture the nonlinear influence of matric suction on shear strength of soil and interfaces. Les interfaces de sol non saturés existent lorsque le sol non saturé est en contact avec des structures comme les fondations, les murs de soutènement et les tuyaux enfouis. L’interface de sol saturé peut être définie comme une couche de sol non saturé à travers laquelle les contraintes sont transférées du sol à la structure, et vice versa. Dans cet article, le comportement en cisaillement des interfaces de sol non saturé est examiné à partir de résultats d’essais en cisaillement direct sur des interfaces d’un sol fin à faible plasticité. Un appareil conventionnel d’essais de cisaillement direct a été modifié afin d’effectuer des essais de cisaillement direct sur des interfaces en contrôlant la succion matricielle. De plus, les résultats ont été utilisés pour définir l’enveloppe de fracture pour des interfaces de sol non saturé ayant des surfaces correspondantes lisses et rugueuses. Les résultats de cette étude démontrent que la succion matricielle contribue à la résistance au cisaillement de pic des interfaces non saturée; cependant la résistance au cisaillement dépassé le pic ne semblait pas varier selon la succion matricielle. Les variations des contraintes normales nettes affectent autant la résistance au cisaillement de pic et post-pic. Les enveloppes de fractures développées avec les courbes de rétention d’eau capturent l’influence non linéaire de la succion matricielle sur la résistance au cisaillement des sols et des interfaces. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...] [article] Shear strength of unsaturated soil interfaces [texte imprimé] / Tariq B. Hamid, Auteur ; Gerald A. Miller, Auteur . - pp. 595-606. Sciences de la Terre Langues : Anglais (eng) in Canadian geotechnical journal > Vol. 46 N° 5 (Mai 2009) . - pp. 595-606 Mots-clés : Soil  Unsaturated  Interface  Shear  strength  Sol  non  saturé  Interface  Résistance  au  cisaillement Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : Unsaturated soil interfaces exist where unsaturated soil is in contact with structures such as foundations, retaining walls, and buried pipes. The unsaturated soil interface can be defined as a layer of unsaturated soil through which stresses are transferred from soil to structure and vice versa. In this paper, the shearing behavior of unsaturated soil interfaces is examined using results of interface direct shear tests conducted on a low-plasticity fine-grained soil. A conventional direct shear test device was modified to conduct direct shear interface tests using matric suction control. Further, the results were used to define failure envelopes for unsaturated soil interfaces having smooth and rough counterfaces. Results of this study indicate that matric suction contributes to the peak shear strength of unsaturated interfaces; however, postpeak shear strength did not appear to vary with changes in matric suction. Variations in net normal stress affected both peak and postpeak shear strength. Failure envelopes developed using the soil-water characteristic curve (SWCC) appeared to capture the nonlinear influence of matric suction on shear strength of soil and interfaces. Les interfaces de sol non saturés existent lorsque le sol non saturé est en contact avec des structures comme les fondations, les murs de soutènement et les tuyaux enfouis. L’interface de sol saturé peut être définie comme une couche de sol non saturé à travers laquelle les contraintes sont transférées du sol à la structure, et vice versa. Dans cet article, le comportement en cisaillement des interfaces de sol non saturé est examiné à partir de résultats d’essais en cisaillement direct sur des interfaces d’un sol fin à faible plasticité. Un appareil conventionnel d’essais de cisaillement direct a été modifié afin d’effectuer des essais de cisaillement direct sur des interfaces en contrôlant la succion matricielle. De plus, les résultats ont été utilisés pour définir l’enveloppe de fracture pour des interfaces de sol non saturé ayant des surfaces correspondantes lisses et rugueuses. Les résultats de cette étude démontrent que la succion matricielle contribue à la résistance au cisaillement de pic des interfaces non saturée; cependant la résistance au cisaillement dépassé le pic ne semblait pas varier selon la succion matricielle. Les variations des contraintes normales nettes affectent autant la résistance au cisaillement de pic et post-pic. Les enveloppes de fractures développées avec les courbes de rétention d’eau capturent l’influence non linéaire de la succion matricielle sur la résistance au cisaillement des sols et des interfaces. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...]