Shaking table tests on seismic response of a subway station structure in ground fissure site

The safety of subway is seriously threatened by the coupling effects of earthquakes and ground fissures. A shaking table test is conducted on a subway station structure in a ground fissure site (structure crossing the ground fissure), and the acceleration response and crack development of model soil with the ground fissure as well as the acceleration response and strain response of the subway station are analyzed. The results demonstrate that the seismic response of the model soil is larger near the ground fissure in a certain range, and the acceleration response of the hanging-wall is larger than that of the footwall with the same distance from the ground fissure. The distribution of the peak acceleration along the height for the subway station in the ground fissure site is related to earthquake intensities. Under small ground motions, the peak acceleration increases with the height of the structures (inverted triangle distribution). Under strong ground motions, the peak acceleration is larger at the top and bottom slabs while smaller at the middle slab ("K"-type distribution). The seismic damage mode of the subway station structure in the ground fissure site is the obvious deformation caused by horizontal shear displacement and the dislocation between the hanging-wall and the footwall. The central column has a serious compression-shear failure, and the connection of the side wall and the roof exhibits tensile damage, resulting in the failure of the underground structures. Because the vertical earthquake increases the dynamic amplification effect and aggravates the dislocation action between the hanging-wall and the footwall in the ground fissure site, the subway station in the ground fissure site is damaged more seriously.