Documents disponibles écrits par cet auteur

Initial shear modulus of remolded sand-clay mixtures / Suguru Yamada in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°7 (Juillet 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°7 (Juillet 2008) . - pp. 960–971 Titre : Initial shear modulus of remolded sand-clay mixtures Type de document : texte imprimé Auteurs : Suguru Yamada, Auteur ; Masayuki Hyodo, Auteur ; Rolando P. Orense, Auteur Année de publication : 2008 Article en page(s) : pp. 960–971 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Shear  modulus  Dynamic  properties  Material  properties  Clays  Mixtures  Cyclic  tests  Soil  dynamics Résumé : This paper presents the dynamic properties of undisturbed and remolded clays and sand-clay mixtures based on the results of undrained hollow cylindrical torsional cyclic simple shear tests. The clays were obtained from different sites having a wide range of plasticity, covering fluvial and marine sediments. The main focus of this investigation is the dynamic properties of sand-clay mixtures whose properties are intermediate between those of clays and sands. The initial shear moduli are examined in terms of fines content, and conventional plasticity index. An equivalent plasticity index has been defined in the present investigation and a better correlation is obtained between the initial shear modulus of sand-clay mixtures and this parameter than with the conventional plasticity index. Further, a simple method has been suggested to determine the equivalent plasticity index based on the conventional consistency limit tests and grain size analysis. An empirical correlation for predicting the initial shear modulus is also proposed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A7%2896 [...] [article] Initial shear modulus of remolded sand-clay mixtures [texte imprimé] / Suguru Yamada, Auteur ; Masayuki Hyodo, Auteur ; Rolando P. Orense, Auteur . - 2008 . - pp. 960–971. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°7 (Juillet 2008) . - pp. 960–971 Mots-clés : Shear  modulus  Dynamic  properties  Material  properties  Clays  Mixtures  Cyclic  tests  Soil  dynamics Résumé : This paper presents the dynamic properties of undisturbed and remolded clays and sand-clay mixtures based on the results of undrained hollow cylindrical torsional cyclic simple shear tests. The clays were obtained from different sites having a wide range of plasticity, covering fluvial and marine sediments. The main focus of this investigation is the dynamic properties of sand-clay mixtures whose properties are intermediate between those of clays and sands. The initial shear moduli are examined in terms of fines content, and conventional plasticity index. An equivalent plasticity index has been defined in the present investigation and a better correlation is obtained between the initial shear modulus of sand-clay mixtures and this parameter than with the conventional plasticity index. Further, a simple method has been suggested to determine the equivalent plasticity index based on the conventional consistency limit tests and grain size analysis. An empirical correlation for predicting the initial shear modulus is also proposed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A7%2896 [...]

Liquefaction resistance of sandy soils under partially drained condition / Yoichi Yamamoto in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 8 (Août 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 8 (Août 2009) . - pp. 1032–1043 Titre : Liquefaction resistance of sandy soils under partially drained condition Type de document : texte imprimé Auteurs : Yoichi Yamamoto, Auteur ; Masayuki Hyodo, Auteur ; Rolando P. Orense, Auteur Année de publication : 2009 Article en page(s) : pp. 1032–1043 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Cyclic  tests  Drainage  Soil  liquefaction  Earthquakes  Sand  Soil  stabilization  Sand Résumé : In order to simulate the effect of drainage on soils adjacent to gravel drains that are installed as countermeasure against liquefaction, several series of cyclic triaxial tests were performed on saturated sands under partially drained conditions. The condition of partial drainage under cyclic loading was simulated in the laboratory using triaxial testing equipment installed with a drainage control valve to precisely regulate the volume of water being drained from test specimens. Effects of both drainage conditions and loading frequencies on cyclic response were incorporated through the coefficient of drainage effect, α∗ . Experimental results showed that for sand exhibiting strain softening, the partially drained response was controlled by the critical effective stress ratio while for sand showing strain hardening behavior, the controlling factor was the phase transformation stress ratio. Moreover, test results indicated that the minimum liquefaction resistance under partially drained conditions can be used as a parameter to describe the liquefaction resistance of sands improved by the gravel drain method. From these results, a simplified procedure for designing gravel drains based on the factor of safety (FL) concept was proposed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000051 [article] Liquefaction resistance of sandy soils under partially drained condition [texte imprimé] / Yoichi Yamamoto, Auteur ; Masayuki Hyodo, Auteur ; Rolando P. Orense, Auteur . - 2009 . - pp. 1032–1043. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 8 (Août 2009) . - pp. 1032–1043 Mots-clés : Cyclic  tests  Drainage  Soil  liquefaction  Earthquakes  Sand  Soil  stabilization  Sand Résumé : In order to simulate the effect of drainage on soils adjacent to gravel drains that are installed as countermeasure against liquefaction, several series of cyclic triaxial tests were performed on saturated sands under partially drained conditions. The condition of partial drainage under cyclic loading was simulated in the laboratory using triaxial testing equipment installed with a drainage control valve to precisely regulate the volume of water being drained from test specimens. Effects of both drainage conditions and loading frequencies on cyclic response were incorporated through the coefficient of drainage effect, α∗ . Experimental results showed that for sand exhibiting strain softening, the partially drained response was controlled by the critical effective stress ratio while for sand showing strain hardening behavior, the controlling factor was the phase transformation stress ratio. Moreover, test results indicated that the minimum liquefaction resistance under partially drained conditions can be used as a parameter to describe the liquefaction resistance of sands improved by the gravel drain method. From these results, a simplified procedure for designing gravel drains based on the factor of safety (FL) concept was proposed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000051

Pile bearing capacity factors and soil crushabiity / Keiji Kuwajima in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 7 (Juillet 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 901–913 Titre : Pile bearing capacity factors and soil crushabiity Type de document : texte imprimé Auteurs : Keiji Kuwajima, Auteur ; Masayuki Hyodo, Auteur ; Adrian F. Hyde, Auteur Année de publication : 2009 Article en page(s) : pp. 901–913 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Piles  Load  bearing  capacity  Friction  Sand  Silica  Calcareous  soils  Soil  compression  Model  tests Résumé : The existence of large magnitude stresses at the tip of a bearing pile is a well known phenomenon leading to crushing of soil grains and thus affecting pile behavior. Classical foundation design calculations which assume that the soil fails in shear and neglect volume change can be safely used where stress levels or particle strengths prevent crushing, however in the case of weak grains or high foundation stresses consideration should be given to the effects of grain crushing and the resulting volumetric compression. Model pile tests have been carried out in two skeletal carbonate sands and a standard silica sand with the aim of examining the variation of skin friction and end bearing capacities with degree of penetration. The mobilization of the strength of crushable soils requires a much higher strain level while at the same time the end bearing pressure on the model piles exceeded 10MPa inducing considerable particle breakage. The peak skin friction for all sands occurred at a settlement normalized by pile diameter, S∕D , of less than 0.1. At this point the carbonate sands generally had lower skin friction values than the silica sand. Further displacement caused a rapid decrease in skin friction for all three materials. At higher lateral stresses the less crushable Toyoura silica sand generated higher skin frictions. Samples of Chiibishi sand were sectioned and photographed. It was observed that a spherical plastic zone was formed at the base of the pile which expanded with increasing S∕D and a degraded layer of broken particles developed around the pile as S∕D increased. Large values of the Marsal particle breakage factor were restricted to a zone extending outwards to one pile radius. An end bearing capacity modification factor has been proposed to adapt the conventional bearing capacity equation for soil crushability. This modification factor is a function of soil compressibility and degree of penetration. The factor was shown to decrease with increasing soil compressibility and increase with normalized penetration S∕D . En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000057 [article] Pile bearing capacity factors and soil crushabiity [texte imprimé] / Keiji Kuwajima, Auteur ; Masayuki Hyodo, Auteur ; Adrian F. Hyde, Auteur . - 2009 . - pp. 901–913. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 7 (Juillet 2009) . - pp. 901–913 Mots-clés : Piles  Load  bearing  capacity  Friction  Sand  Silica  Calcareous  soils  Soil  compression  Model  tests Résumé : The existence of large magnitude stresses at the tip of a bearing pile is a well known phenomenon leading to crushing of soil grains and thus affecting pile behavior. Classical foundation design calculations which assume that the soil fails in shear and neglect volume change can be safely used where stress levels or particle strengths prevent crushing, however in the case of weak grains or high foundation stresses consideration should be given to the effects of grain crushing and the resulting volumetric compression. Model pile tests have been carried out in two skeletal carbonate sands and a standard silica sand with the aim of examining the variation of skin friction and end bearing capacities with degree of penetration. The mobilization of the strength of crushable soils requires a much higher strain level while at the same time the end bearing pressure on the model piles exceeded 10MPa inducing considerable particle breakage. The peak skin friction for all sands occurred at a settlement normalized by pile diameter, S∕D , of less than 0.1. At this point the carbonate sands generally had lower skin friction values than the silica sand. Further displacement caused a rapid decrease in skin friction for all three materials. At higher lateral stresses the less crushable Toyoura silica sand generated higher skin frictions. Samples of Chiibishi sand were sectioned and photographed. It was observed that a spherical plastic zone was formed at the base of the pile which expanded with increasing S∕D and a degraded layer of broken particles developed around the pile as S∕D increased. Large values of the Marsal particle breakage factor were restricted to a zone extending outwards to one pile radius. An end bearing capacity modification factor has been proposed to adapt the conventional bearing capacity equation for soil crushability. This modification factor is a function of soil compressibility and degree of penetration. The factor was shown to decrease with increasing soil compressibility and increase with normalized penetration S∕D . En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000057

Strain-dependent dynamic properties of remolded sand-clay mixtures / Suguru Yamada in Journal of geotechnical and geoenvironmental engineering, Vol. 134 N°7 (Juillet 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°7 (Juillet 2008) . - pp. 972–981 Titre : Strain-dependent dynamic properties of remolded sand-clay mixtures Type de document : texte imprimé Auteurs : Suguru Yamada, Auteur ; Masayuki Hyodo, Auteur ; Rolando P. Orense, Auteur Année de publication : 2008 Article en page(s) : pp. 972–981 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Shear  modulus  Damping  Dynamic  properties  Material  properties  Clays  Mixtures  Cyclic  tests  Soil  dynamics Résumé : A series of undrained cyclic torsional simple shear tests using hollow cylindrical torsional shear apparatus was carried out to investigate the dynamic shear moduli and damping properties of clayey specimens with various sand contents and plasticity indices. The clayey soils used were collected from various sites along the coast of west Japan. Among these clayey soils, a clay sample with intermediate plasticity and another with high plasticity were mixed with silica sand at different proportions in order to examine the dynamic properties of sand-clay mixtures. In addition, experiments were carried out on undisturbed and remolded natural clay specimens with various plasticities. The effects of plasticity, loading frequency and confining pressure on the strain dependent normalized shear modulus and damping ratio were examined. Based on the results, empirical correlations for predicting the normalized shear modulus and damping ratio of remolded sand-clay mixtures at various shear strain levels were proposed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A7%2897 [...] [article] Strain-dependent dynamic properties of remolded sand-clay mixtures [texte imprimé] / Suguru Yamada, Auteur ; Masayuki Hyodo, Auteur ; Rolando P. Orense, Auteur . - 2008 . - pp. 972–981. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 N°7 (Juillet 2008) . - pp. 972–981 Mots-clés : Shear  modulus  Damping  Dynamic  properties  Material  properties  Clays  Mixtures  Cyclic  tests  Soil  dynamics Résumé : A series of undrained cyclic torsional simple shear tests using hollow cylindrical torsional shear apparatus was carried out to investigate the dynamic shear moduli and damping properties of clayey specimens with various sand contents and plasticity indices. The clayey soils used were collected from various sites along the coast of west Japan. Among these clayey soils, a clay sample with intermediate plasticity and another with high plasticity were mixed with silica sand at different proportions in order to examine the dynamic properties of sand-clay mixtures. In addition, experiments were carried out on undisturbed and remolded natural clay specimens with various plasticities. The effects of plasticity, loading frequency and confining pressure on the strain dependent normalized shear modulus and damping ratio were examined. Based on the results, empirical correlations for predicting the normalized shear modulus and damping ratio of remolded sand-clay mixtures at various shear strain levels were proposed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A7%2897 [...]