A DEM Investigation on the Effect of Gradation on the Liquefaction Response and Fabric Evolution of Soils

Abstract Assessment of liquefaction triggering potential is an important aspect in the design of critical infrastructure. This paper uses Discrete Element Modeling (DEM) simulations to explore the effect of gradation on the liquefaction triggering and deformation accumulation in coarse-grained soils. Cyclic direct simple shear (DSS) simulations indicate that the state parameter, as defined as the difference between the current and critical state void ratios at a the same mean effective stress (p’), is a more robust metric for relating the soil state to the liquefaction resistance of sands. At the same state parameter, more broadly graded soils have greater resistance to liquefaction and accumulate smaller post-liquefaction deformations. These trends are explained by the more broadly graded soils having more contacts per particle than the poorly-graded soils and developing greater anisotropy in the strong contact force network during shearing. This analysis sheds light on the effects of gradation on the micro and marco responses in sands, and how they relate to soil liquefaction.