Finite Element Analysis of Overlying Soil Failure Based on Fault Dip Angle

Abstract

When the strong earthquake occurs, the deformation response and rupture of the overlying soil are very complicated. In this paper, the influence of fault dip angle on the surface deformation and rupture of overlying soil is analyzed by means of finite element numerical simulation. When the vertical dislocation of the fault is about 3∼5% of the thickness of the overlying soil layer, the surface rupture occurs only when the fault dip angle is 45°. When the vertical displacement of the fault increases to 10% of the thickness of the overlying soil layer, surface rupture occurs under three working conditions of 45°, 70° and 90° of fault dip angle. With the increase of the dip angle from 45°, 70° to 90°, the surface equivalent strain is gradually smaller, the deformation of the overlying soil is smaller, and the deformation width of the upper wall will change from about 2 times that of the lower wall to the same as the lower wall. The deformation and rupture of the overlying soil first begin with the fracture of the soil mass at the interface between the fault bedrock and the soil. With the increase of the dislocation quantity, the surface also will appear 1 breakpoint when the fault angle is 45° and 70°, the ground surface will appear 2 breakpoints when the fault angle is 90°, and at last overlying soil is broken through.