SPH-FEM coupled simulation of SSI for conducting seismic analysis on a rectangular underground structure

A reliable simulation of soil-structure interaction (SSI) is the precondition for understanding properly the dynamic response characteristics and earthquake disaster mechanism of underground structures. This paper adopts Smoothed Particle Hydrodynamics-Finite Element Method (SPH-FEM) coupled method to address the SSI issue. The coupled method takes advantage of the convenience of SPH in simulating the particle features of soils. The advantages of the presented method are capable of tracking the location information and motion of soils at any moment, and the deformation process inside the near-structure soils can also be captured during an earthquake. Meanwhile, it can also be made use of the accuracy of FEM in handling boundary issues and solving structural dynamics. Analysis results indicate that not only the racking deformation mode is observed, but also a rocking vibration mode that is non-negligible can be found for a rectangular underground structure under transverse seismic excitation. The rocking vibration mode is shown as the incline of top and bottom slabs, which is caused by the asymmetric seismic action on two opposite side-walls resulting from the different soil-structure contact status. The analysis clearly shows that the seismic earth pressure is a result of the interaction between soil and structure in an earthquake. The distribution and magnitude of seismic earth pressure are influenced by the magnitude of soil deformation and soil-structure contact status.