Research on dynamic response of orthogonal tunnel lining under earthquake

Relying on the metro line 4 interval tunnel in Chongqing, the dynamic response of orthogonal tunnels at different locations under the influence of horizontal seismic wave sat different time intervals are studied with an earthquake of intensity VIII. By analysis the ANSYS numerical model simulation results and actual monitoring results, the following conclusions can be derive. (1) The lining stress change shows a positive parabolic phenomenon, and the optimal spacing of the upper and lower tunnels can be derived from the stress change as 1.5 times the hole diameter. (2) By studying the displacement values of the monitoring points in the orthogonal tunnel with different spacing between the upper and lower tunnels, it can be seen that the displacement in the horizontal direction of each monitoring point is significantly larger than that in the vertical direction, which leads to the conclusion that the seismic wave in the horizontal direction has a greater effect on the horizontal direction of the tunnel lining. (3) The upper tunnel is most affected by seismic waves at the arch top, followed by the arch waist and the arch foot, and finally the arch bottom. (4) The peak of horizontal displacement in the orthogonal tunnel under the action of horizontal seismic waves is 20 m from the portal of the upper tunnel, rather than the orthogonal part. The research results can provide a helpful manual for the design and construction of orthogonal tunnels in earthquake areas.