Documents disponibles écrits par cet auteur

Effect of fine particle migration on the small-strain stiffness of unsaturated soils / Bashar Alramahi in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 4 (Avril 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 4 (Avril 2010) . - pp. 620-628 Titre : Effect of fine particle migration on the small-strain stiffness of unsaturated soils Type de document : texte imprimé Auteurs : Bashar Alramahi, Auteur ; Khalid A. Alshibli, Auteur ; Dante Fratta, Auteur Année de publication : 2010 Article en page(s) : pp. 620-628 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Unsaturated  soils  Wave  propagation  X-ray  microcomputed  tomography  Particle  migration  Shear  modulus  Stiffness Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The paper presents the results of an experimental investigation of fine particle migration from pore body to the pore throat and toward the contact between particles and its effect on skeleton stiffness of granular materials. We hypothesize that the suspended colloids in the pore fluid migrate and deposit on the contact surface between the skeleton-forming particles and change the magnitude of the soil stiffness. Three specimens were prepared using uniform spherical glass particles that were saturated with deionized water and kaolinite or silt-base slurries. The specimens were drained by evaporation which retained the fines in the soil while increasing the matric suction. Changes in soil dynamic stiffness were evaluated using piezoelectric transducers while the migration of fines and the changes of the properties of the pore fluid were monitored using synchrotron X-ray microcomputed tomography (SMCT) on identical specimens. The wave propagation experiments show that the stiffness of the tested specimens increased at different rates during the drying processes. These measurements were complemented with SMCT scanning analysis that shows an increase in mass density of the remaining slurry as the pore fluid concentrated near the particle contacts. The results indicate that the soil stiffness increase due to the alteration of the pore fluid at the particles’ contact and changes caused at the contact behavior itself. These results provide an insight about parameters that influence soil stiffness which may help in better predictions of stiffness changes in compacted soils during moisture changes. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i4/p620_s1?isAuthorized=no [article] Effect of fine particle migration on the small-strain stiffness of unsaturated soils [texte imprimé] / Bashar Alramahi, Auteur ; Khalid A. Alshibli, Auteur ; Dante Fratta, Auteur . - 2010 . - pp. 620-628. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 4 (Avril 2010) . - pp. 620-628 Mots-clés : Unsaturated  soils  Wave  propagation  X-ray  microcomputed  tomography  Particle  migration  Shear  modulus  Stiffness Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The paper presents the results of an experimental investigation of fine particle migration from pore body to the pore throat and toward the contact between particles and its effect on skeleton stiffness of granular materials. We hypothesize that the suspended colloids in the pore fluid migrate and deposit on the contact surface between the skeleton-forming particles and change the magnitude of the soil stiffness. Three specimens were prepared using uniform spherical glass particles that were saturated with deionized water and kaolinite or silt-base slurries. The specimens were drained by evaporation which retained the fines in the soil while increasing the matric suction. Changes in soil dynamic stiffness were evaluated using piezoelectric transducers while the migration of fines and the changes of the properties of the pore fluid were monitored using synchrotron X-ray microcomputed tomography (SMCT) on identical specimens. The wave propagation experiments show that the stiffness of the tested specimens increased at different rates during the drying processes. These measurements were complemented with SMCT scanning analysis that shows an increase in mass density of the remaining slurry as the pore fluid concentrated near the particle contacts. The results indicate that the soil stiffness increase due to the alteration of the pore fluid at the particles’ contact and changes caused at the contact behavior itself. These results provide an insight about parameters that influence soil stiffness which may help in better predictions of stiffness changes in compacted soils during moisture changes. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i4/p620_s1?isAuthorized=no

Strength properties of JSC-1A lunar regolith simulant / Khalid A. Alshibli in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 5 (Mai 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 5 (Mai 2009) . - pp. 673–679 Titre : Strength properties of JSC-1A lunar regolith simulant Type de document : texte imprimé Auteurs : Khalid A. Alshibli, Auteur ; Alsidqi Hasan, Auteur Année de publication : 2009 Article en page(s) : pp. 673–679 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Moon  Soil  strength  Shear  strength  Friction  Dilatancy Résumé : The paper presents a description of physical properties and a characterization of shear strength behavior of JSC-1A lunar regolith simulant. Specific gravity of solids, particle size analysis, and minimum and maximum index densities were measured according to ASTM standards. A series of axisymmetric triaxial experiments were conducted on JSC-1A specimens at two densities and a wide range of confining pressures. The stress-strain and volume change behavior of JSC-1A is presented and discussed. The results show that the peak friction and dilatancy angles are highly influenced by specimen density and confining pressure. Two models were developed to predict the peak friction and dilatancy angle, as a function of relative density and mean effective stress at the critical state. It was found that JSC-1A closely resembles the morphology and specific gravity of solids of some of Apollo regolith samples reported in the literature. Shear strength properties are presented within the framework of Mohr–Coulomb and friction-dilatancy theories. The effect of reduced moon gravity on strength parameters is also presented and discussed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000068 [article] Strength properties of JSC-1A lunar regolith simulant [texte imprimé] / Khalid A. Alshibli, Auteur ; Alsidqi Hasan, Auteur . - 2009 . - pp. 673–679. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 5 (Mai 2009) . - pp. 673–679 Mots-clés : Moon  Soil  strength  Shear  strength  Friction  Dilatancy Résumé : The paper presents a description of physical properties and a characterization of shear strength behavior of JSC-1A lunar regolith simulant. Specific gravity of solids, particle size analysis, and minimum and maximum index densities were measured according to ASTM standards. A series of axisymmetric triaxial experiments were conducted on JSC-1A specimens at two densities and a wide range of confining pressures. The stress-strain and volume change behavior of JSC-1A is presented and discussed. The results show that the peak friction and dilatancy angles are highly influenced by specimen density and confining pressure. Two models were developed to predict the peak friction and dilatancy angle, as a function of relative density and mean effective stress at the critical state. It was found that JSC-1A closely resembles the morphology and specific gravity of solids of some of Apollo regolith samples reported in the literature. Shear strength properties are presented within the framework of Mohr–Coulomb and friction-dilatancy theories. The effect of reduced moon gravity on strength parameters is also presented and discussed. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000068