Effects of structure on the mechanical behavior of loess: implications for flowslides in cemented soils
Fangzhou Liu, J. David Frost, Jorge Macedo, Qiang Xu
In the proceedings of: GeoVirtual 2020: 73rd Canadian Geotechnical ConferenceABSTRACT: Loess contains predominately silt-sized quartz grains that are bonded by various cementation agents, that is of significant interest to the understanding of the mechanical properties of lightly cemented soils. Loess is problematic upon wetting as its metastable structure can rapidly transform from a cemented solid body to a fluidized material. The results of series of isotropically consolidated undrained tests (CIU) compare the large-strain behaviors of intact and reconstituted specimens, that show state-dependent flow instability due to the effect of structure. A constitutive understanding is gained using NorSand model by comparing the computed undrained behaviors of intact and reconstituted loess at the same state parameter. The results confirms the strong effect of structure on flow instability. The drained-to-undrained transition in the loading path of loess is simulated, and indicates a rapid reduction in strength under such a transition for loess, thereby the triggering mechanism of loess flowslides.
RÉSUMÉ: Le loess contient principalement des grains de quartz de la taille d'un limon liés par divers agents de cimentation, ce qui présente un intérêt important pour la compréhension des propriétés mécaniques des sols légèrement cimentés. Le loess est problématique lors du mouillage car sa structure métastable peut rapidement se transformer d'un corps solide cimenté en un matériau fluidisé. Les résultats d'une série de tests non drainés (CIU) isotropiquement consolidés comparent les comportements à grande déformation d'échantillons intacts et reconstitués, qui montrent une instabilité de l'écoulement dépendante de l'état en raison de l'effet de la structure. Une compréhension constitutive est acquise à la lumière du modèle NorSand en comparant les comportements non drainés calculés de loess intact et reconstitué au même paramètre d'état. Les résultats confirment le fort effet de la structure sur l'instabilité de l'écoulement. La transition drainée à non drainée dans le chemin de chargement du loess est simulée, ce qui indique une réduction rapide de la résistance sous une telle transition pour le loess, et donc le mécanisme de déclenchement des coulées de flux de loess.
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Liu, Fangzhou, Frost, J. David, Macedo, Jorge, Xu, Qiang (2020) Effects of structure on the mechanical behavior of loess: implications for flowslides in cemented soils in GEO2020. Ottawa, Ontario: Canadian Geotechnical Society.
@article{Liu_GEO2020_508,
author = {Liu, Fangzhou}, {Frost, J. David}, {Macedo, Jorge}, {Xu, Qiang},
title = Effects of structure on the mechanical behavior of loess: implications for flowslides in cemented soils ,
year = 2020
}
title = Effects of structure on the mechanical behavior of loess: implications for flowslides in cemented soils ,
year = 2020
}