Performance of existing tunnels due to shield under-crossing considering #br#
buoyancy effect
Gan Xiaolu1,2 Yu Jianlin1,2 Gong Xiaonan1,2 Zhu Min3 Cheng Kang1,2 Hou Yongmao4
1. Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China;
2. Engineering Research Center of Urban Underground Development of Zhejiang Province, Hangzhou 310058, China;
3. Shenzhen University, Shenzhen 518060, China; 4. Shanghai Tunnel Engineering Co., Ltd., Shanghai 200082, China
Abstract： The process of shield excavation disturbs existing tunnels and may cause structural damages of the tunnels. Because the weight of the shield segment is much lighter than the weight of the excavated soil, the buoyancy effect induced by the new tunneling may affect existing tunnels. A two-stage analysis method considering the uplift of the new tunnel is adopted to calculate the longitudinal displacement of the existing tunnels due to new tunneling underneath, and its applicability is validated against field measurements. The results show that the calculation results presented in this paper are in good agreement with the measured data. Controlling the tunnel uplift and reducing the new tunnel diameter can effectively reduce the tunnel heave caused by the buoyancy effect. The proposed method can provide a theoretical reference for evaluating the effect of new tunnel construction on the existing tunnel in similar projects.
