Seismic Response of Shallow Foundations Resting on Liquefiable Sand

Abstract

In this study, the seismic response of shallow foundations resting on a liquefiable soil layer is modeled using a coupled smoothed particle hydrodynamics (SPH)-discrete element method (DEM) scheme. In this framework, the soil deposit is represented by an assembly of DEM particles, and the fluid domain is lumped into a set of SPH particles carrying local fluid properties. The averaged forms of Navier-Stokes equations dictate the motion of the fluid-particle mixture, and the interphase forces are estimated using well-known semi-empirical equations. A saturated soil-foundation system with an average contact pressure of 50~kPa was created using the coupled scheme. The foundation block was composed of a collection of DEM particles glued together by high-stiffness bonds. No-penetration boundary condition was applied to all sides of the foundation block to allow for fluid-foundation interaction. The model was subjected to a strong base acceleration, and the response was analyzed and compared to the free-field. The obtained results indicate that ground settlement in the soil-foundation system mostly originated from co-seismic deviatoric deformations, while volumetric strains were the main contributing factor at the free-field. In addition, unlike the soil-foundation system, a large part of the free-field settlement occurred post-shaking.