Three-dimensional (3D) dynamic finite element modeling of the effects of a geological fault on the seismic response of underground caverns

Abstract

Faults generally have detrimental effects on the stability of underground caverns. During earthquakes these destructive effects are magnified. In this paper, a fully three-dimensional (3D) dynamic finite element model is developed to assess the effects of a fault on the seismic behaviors of underground caverns. A nonlinear thin-layer element model is developed to describe the complex mechanical properties of the fault. The developed model is first verified by two traditional shear experiments. Then the effects of fault parameters (e.g. the intersection angle, fault thickness, fault shear strength), in situ stress states and the intensity of earthquake on seismic response of underground cavern are analyzed. The predicted results show that when the fault strike is parallel to the longitudinal axis of the cavern and the intersection angle between the fault and the vertical axis in the cavern cross section is approximately 40°, the cavern is in the most unstable state. In addition, the cavern is likely to suffer a collapse when critical peak ground acceleration (PGA) is around 0.3 g under the cases studied in this work.