SHAKING TABLE TEST AND NUMERICAL SIMULATION ON SUBWAY STATION IN GROUND FISSURE AREA

The dynamic effect and the dislocation of hanging-wall and footwall in ground fissure area seriously affect the safety of underground structures. Xi’an Kangfulu station was investigated, which was located in ground fissure area. A shaking table test on subway station in ground fissure area subjected to coupled horizontal-vertical (bidirectional) earthquake excitations was carried out, in which the acceleration response of the model soil, the acceleration response of model station, and the strain distribution characteristics of model station were analyzed. The three-dimensional models of stations in fissured and non-fissured ground were established using Abaqus, respectively. The inter-story drift ratios and seismic damage distribution-rules of subway station under two kinds of area conditions were studied. The results indicated that the dynamic differential response of the hanging-wall and footwall and dislocation between the hanging-wall and footwall in ground fissure area under the coupled horizontal-vertical earthquake excitations were more significant than those under the horizontal earthquake excitations. Compared with the station in the non-fissured ground, inter-story drift ratios of the station in fissured ground increased obviously, and the damage of structural members was more severe. The reason could be that the void area was easy to develop between the soil with ground cracks and the station, resulting in the enhanced vibration response of the station. Meanwhile, the dislocation between the hanging-wall and footwall would produce an additional shear effect on the station, which was mainly caused by the vertical earthquake. Consequently, the pillar was more prone to severe damage, resulting in the overall failure of the station.