The Reasonable Layout of Cross Passages for Qianjiang River Tunnel Based on Seismic Analysis

Numerical modeling and Response Displacement Method are applied to assess the effects of the presence of cross passages and geological formations on the seismic responses of the Qianjiang River tunnel, in order to determine the proper locations of cross passages. The numerical analysis shows that the presence of cross passages affects the longitudinal seismic response of the main tunnel significantly within a 25-m distance from the intersections of cross passages with main tunnels. So, the possible local failure of the intersections will be a major concern. This is largely attributed to the complicated geologic formations and irregular ground conditions. The analysis based on the Response Displacement Method indicates that cross passages in flat and uniform ground layers can mitigate the local failure at the intersections. Optimal location for cross passages are proposed based on the detailed analysis of the geologic profiles of Qianjiang River Tunnel.