Analysis of Earthquake Fault Rupture Propagation through Cohesive Soil

Abstract

An improved understanding of earthquake fault rupture propagation through saturated clay would assist engineers in siting and designing facilities to be constructed in regions where cohesive soils overlie potentially active faults. The results from numerical analyses suggest that the finite-element method can be applied to this class of problem provided that the soil's nonlinear stress-strain behavior is adequately modeled. It was found that the height of the shear rupture zone in the overlying saturated clay soil at a specified base rock fault displacement depends primarily on the soil's failure strain. As the clay's failure strain decreases, the shear rupture zone in the clay overlying the bedrock fault propagates further at a specified base displacement. Other material parameters such as soil shear strength and stiffness also affect the fault rupture process, but not to the extent of failure strain. The orientation of the shear rupture zone through the soil depends largely on the orientation of the underlying bedrock fault plane.