Micromechanical Analyses of Saturated Granular Soils

Phenomenological (macroscale) models are commonly used in analyses of saturated soil systems. In these models, the momentum exchange between the solid and fluid phases is generally accounted for using Darcy's law. A hydromechanical model is presented herein to study the coupled mesoscale pore water flow and microscale solid matrix deformation of granular soils. The fluid motion is idealized using averaged Navier-Stokes equations, and the discrete element method is employed to model soil particles. Fluid-particle interactions are addressed using established semi-empirical relationships. The proposed approach was validated using published experimental results. Numerical simulations were conducted to investigate the liquefaction of soil deposits subjected to a critical hydraulic gradient. Pore water flow through a liquefied coarse sandy soil was shown to deviate from Darcy's law and eventually become locally nonlaminar: At steady state, the associated permeabilities were found to be comparable to those at subcritical conditions.