Abstract:This study aims to determine the effect of excavation process and retaining structure as a permanent structure in the seismic design of open excavation metro stations. A finite element model of two-story two-span rectangular frame is established by Plaxis2D based on an open cut subway station with cast-in-place pile as the retaining structure in Zhengzhou City. The constitutive model of hardening soil is adopted to assess earthquake resistance. Results showed that under seismic load, the design value of the upper bending moment of the structure is 31% smaller without considering excavation than that considering excavation. The design of the side wall and floor is conservative, with bending moments larger than 87% and 64%, respectively. If excavation is neglected, then the calculation error of shear force on the lower sidewall increases with the depth from 36% to 122%. However, the influence of stiffness reduction of the diaphragm wall on the internal force is less than 5%. Therefore, in the seismic design of structures on this kind of soft soil, the influence of excavation and the diaphragm wall within the design life should be considered. The bottom of the shear wall and the top and bottom of the middle column should also be emphasized.
