Discrete Element Analysis of Earthquake Fault Rupture-Soil-Foundation Interaction

Abstract

Earthquake fault rupture-soil-foundation interaction (FR-SFI) was simulated using the discrete element method (DEM) with irregularly shaped sphere-clusters to capture the three-dimensional nature of sand grains. High-performance computing simulations of free-field fault rupture and FR-SFI compared well with geotechnical centrifuge experiments in terms of shear rupture development, surface deformation, and foundation response. Micromechanical analyses of particle rotations, interparticle contacts, and void ratio distributions provided key insight into the mechanisms of FR-SFI. Particle rotations showed clearly where rupture surfaces developed, and the distributions of void ratios showed which rupture surfaces softened fully. The rupture surfaces for reverse fault displacement deflect systematically toward the hanging wall side of the foundation as its contact pressure increases. The shear rupture produced by normal faulting migrates from one path propagating toward the hanging wall side of the foundation to a second path propagating toward the footwall side of the foundation due to the presence of the foundation. DEM shows promise for evaluating earthquake FR-SFI.