Abstract: Based on the theories of coupled interaction in saturated soil and dynamic soil-structure interaction, the response of subway structure in fully saturated liquefiable soil under earthquake excitation is investigated using the effective-stress based finite element program Dyna-Swandyne-II. A generalized plasticity model, Pastor-Zienkiewicz III model, is used to model the cyclic behavior of soil; and finite element procedure based on the u-p form of Biot theory is employed to conduct the coupled analysis. The nonlinearity of the interaction between soil and subway structure is fully considered. The dynamic response of subway structure, including the internal forces, the acceleration, and the vertical and horizontal displacements, are analyzed. The results showed that the subway structure may uplift due to the earthquake induced liquefaction, which shall lead to severe damage in the structure; and that the maximum seismic internal forces occurred at the connections of the structure elements and their reinforcement must be carefully designed.

Key words: underground structure, liquefaction dynamic interaction, dynamic coupled analysis, uplift