A Constitutive Model for Flow Liquefaction of Clay Sand

Flow liquefaction has ever been a serious concern in the geotechnical engineering practice. This phenomenon has occurred in numerous destructive seismic events, and it has highlighted the necessity of understanding both the fundamentals of soil behavior and associate mechanisms triggering the flow liquefaction instability. Using the equivalent void ratio concept, a sand constitutive model originally formulated within the bounding surface plasticity context and the critical state soil mechanics has been modified to simulate the mechanical behavior of sands containing plastic fines. The modified constitutive model is systematically calibrated and validated versus results of the undrained triaxial tests on the sand specimens containing varying fines contents. The results of this study indicated the efficiency of the modified constitutive model in predicting transition of the behavior from non-flow to flow due to the increase in clay content. This study improves the understanding of clay effect on sand behavior during undrained conditions and flow instability in clay sands.

Keywords:

Bounding surface plasticity , Undrained behavior , Flow instability , Clay sands , Equivalent void ratio