Abstract:The scale of the Hutong Phase II Baoshan Tunnel Project is a single-tunnel double-track tunnel. The length of shield section is about 2 km. The construction is carried out by using the slurry balance shield tunneling method. The outer diameter of the shield segments is 13.1 m. According to the route planning scheme, the tunnel runs parallel to the Tongji Expressway Elevated Bridge throughout the entire process. The distance to Tongji Expressway starts from the nearest 3 m and gradually decreases. To analyze the impact of short-distance tunnel passage on the existing bridge pile foundations, MIDAS GTS finite element software is used to establish the finite element models for two typical cross-sections with different net distances between pile foundations and tunnel edges in order to simulate the construction process of tunnel side crossing elevated bridges. Based on the degree of impact on pile foundations, the corresponding protective measures with different stiffness isolation piles are proposed. The results indicate that as the increase of clear distance between the elevated bridge pile foundation and the tunnel edge, the stiffness of the isolation pile needs to be gradually improved in order to effectively reduce the impact of shield tunneling construction on the elevated bridge.
