Documents disponibles écrits par cet auteur

Discrete element modeling of contact creep and aging in sand / Yu-Hsing Wang in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°9 (Septembre 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1407–1411 Titre : Discrete element modeling of contact creep and aging in sand Type de document : texte imprimé Auteurs : Yu-Hsing Wang, Auteur ; Dapeng Xu, Auteur ; King-Yuen Tsui, Auteur Année de publication : 2008 Article en page(s) : pp. 1407–1411 Note générale : Geotechnical and gzoenvironmental negineering Langues : Anglais (eng) Mots-clés : Sand  Contact  pressure  Creep  Aging  Stiffness  Dilatancy Résumé : In this study, aging in dry, clean sand induced by contact creep is investigated through numerical simulations using the discrete element method. Simulation results demonstrate that contact creep initiates the redistribution of contact forces. Although contact creep produces a very small decrease in porosity (approximately 1.7%), a significant change in the contact force distribution is produced in the aged sample. The contact forces ultimately become more uniform in both magnitude and spatial distribution. This homogenization of contact forces leads to more stable force chains and therefore produces an increase in the small-strain stiffness, early strength, and dilatancy in the aged sample. Such increases are not found in the sample prepared to the same porosity as the aged sample but without aging. This is because, in generating this sample, the contact creep is not allowed and therefore its associated contact force distribution is less homogenized compared with that in the aged sample. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2814 [...] [article] Discrete element modeling of contact creep and aging in sand [texte imprimé] / Yu-Hsing Wang, Auteur ; Dapeng Xu, Auteur ; King-Yuen Tsui, Auteur . - 2008 . - pp. 1407–1411. Geotechnical and gzoenvironmental negineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1407–1411 Mots-clés : Sand  Contact  pressure  Creep  Aging  Stiffness  Dilatancy Résumé : In this study, aging in dry, clean sand induced by contact creep is investigated through numerical simulations using the discrete element method. Simulation results demonstrate that contact creep initiates the redistribution of contact forces. Although contact creep produces a very small decrease in porosity (approximately 1.7%), a significant change in the contact force distribution is produced in the aged sample. The contact forces ultimately become more uniform in both magnitude and spatial distribution. This homogenization of contact forces leads to more stable force chains and therefore produces an increase in the small-strain stiffness, early strength, and dilatancy in the aged sample. Such increases are not found in the sample prepared to the same porosity as the aged sample but without aging. This is because, in generating this sample, the contact creep is not allowed and therefore its associated contact force distribution is less homogenized compared with that in the aged sample. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2814 [...]

Experimental characterization of dynamic property changes in aged sands / Yu-Hsing Wang in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N°2 (Février 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°2 (Février 2009) . - pp. 259–270 Titre : Experimental characterization of dynamic property changes in aged sands Type de document : texte imprimé Auteurs : Yu-Hsing Wang, Auteur ; King-Yuen Tsui, Auteur Année de publication : 2009 Article en page(s) : pp. 259–270 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Sand  Aging  Shear  modulus  Damping  Creep Résumé : This study investigates the aging effects on the small-strain shear modulus and damping ratio of sands and offers explanations for the measured results based on the concept of contact-force homogenization. Resonant column tests of aged sands under various aging conditions were conducted. The results show that loose sands exhibit greater aging effects than dense sands do at a confining pressure of 35kPa and the effects are completely opposite when the aging pressure is increased to 100kPa . The aging effects can be partially erased by unloading-reloading; the remaining effects can be restored when the applied pressure is the same as the original pressure used during aging and cannot be further erased by additional unloading-reloading cycles. The stress history is also a factor that affects aging behavior: unloading reloading and overconsolidation can reduce the aging rate in terms of the shear-modulus increase. The aging effects, however, can be wiped out by large strain shearing. An addition of fines (dry kaolinite powder) in the sand samples can increase the aging rate because of higher creep made by the kaolinite. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A2%2825 [...] [article] Experimental characterization of dynamic property changes in aged sands [texte imprimé] / Yu-Hsing Wang, Auteur ; King-Yuen Tsui, Auteur . - 2009 . - pp. 259–270. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N°2 (Février 2009) . - pp. 259–270 Mots-clés : Sand  Aging  Shear  modulus  Damping  Creep Résumé : This study investigates the aging effects on the small-strain shear modulus and damping ratio of sands and offers explanations for the measured results based on the concept of contact-force homogenization. Resonant column tests of aged sands under various aging conditions were conducted. The results show that loose sands exhibit greater aging effects than dense sands do at a confining pressure of 35kPa and the effects are completely opposite when the aging pressure is increased to 100kPa . The aging effects can be partially erased by unloading-reloading; the remaining effects can be restored when the applied pressure is the same as the original pressure used during aging and cannot be further erased by additional unloading-reloading cycles. The stress history is also a factor that affects aging behavior: unloading reloading and overconsolidation can reduce the aging rate in terms of the shear-modulus increase. The aging effects, however, can be wiped out by large strain shearing. An addition of fines (dry kaolinite powder) in the sand samples can increase the aging rate because of higher creep made by the kaolinite. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282009%29135%3A2%2825 [...]