Deformation calculation of underlying shield tunnel caused by unloading of foundation pit considering excavation width
WEI Gang1，2，GUO Binglai3，WANG Zhe3，LIU Jiaying1
(1. Key Laboratory of Safe Construction and Intelligent Maintenance for Urban Shield Tunnels of Zhejiang Province，Hangzhou City University，Hangzhou，Zhejiang 310015，China；2. Zhejiang Engineering Research Center of Intelligent Urban Infrastructure，Hangzhou City University，Hangzhou，Zhejiang 310015，China；3. Institute of Geotechnical Engineering，Zhejiang University of Technology，Hangzhou，Zhejiang 310014，China)
Abstract：To calculate the influence of the uplift deformation of the foundation pit bottom on the longitudinal deformation of the underlying tunnel, the calculation model of foundation pit excavation deformation is established. A cooperative tunnel model of rotation and staggered platform deformation is adopted. Based on the virtual image technique，the formulas of longitudinal deformation of the underlying tunnel caused by the excavation of the foundation pit are derived. Three sets of typical cases were selected for calculation and analysis. The B-W and B-P methods are compared to verify the correctness of the calculation method. Moreover，the influence of four factors，namely the maximum uplift of the pit bottom，the excavation width and depth of the pit and the buried depth of the tunnel are analyzed. The results show that there is a positive correlation between the maximum uplift value of the foundation pit bottom and the maximum uplift value of the underlying tunnel. As the excavation width of the foundation pit increases，the uplift value and uplift range of the tunnel increase accordingly. The buried depth and the uplift value of the underlying tunnel show a nonlinear decreasing law. The longitudinal deformation of the underlying tunnel can be effectively controlled by reducing the uplift deformation of the pit bottom and the pit excavation width along the tunnel axis.
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2023, Vol. 42 
