Numerical Simulation for Dynamic Response Characteristics of Tunnel near Fault

In order to obtain the dynamic response of the tunnel near ground fault, finite element software MIDAS NX was used to establish the numerical models of the tunnel near ground fault and that were analyzed using the nonlinear time-history method. The effect of fault-tunnel relative distance and earthquake wave excitation peak on the dynamic response of tunnel was studied and the minimum safe distance between the fault and the tunnel was discussed. Research results show that: (1) the change tendency of the vertical displacement of each measuring point is similar, and along with the increase of fault-tunnel relative distance, the vertical displacement of tunnel gradually reduce and finally tends to be stable. (2) Logarithmic function can well fit the relationship between fault-tunnel relative distance and vertical displacement of each measuring point, and the fitting correlation coefficient R-2 is close to 1. (3) Along with the increase of fault-tunnel relative distance, the acceleration response of each measuring point gradually decrease. Along with the increase of excitation peak of earthquake wave, the acceleration response peak of each measuring point increases. (4) When the fault-tunnel relative distance is less than 30m, the plastic zone of surrounding rock of tunnel and the plastic zone of fault have been through, and the plastic zone of surrounding rock of tunnel is mainly distributed in the left arch shoulder, vault and right arch foot, arch waist. (5) The minimum safe distance of the seismic fortification between fault and tunnel is about 90m. The research results can provide useful reference for the seismic design of tunnel.