The Study On Surface Subsidence And Vibration Induced By Hefei Subway Shield Tunneling Between Shihe Road Station And Qingxi Road Station

Based on the shield construction of Hefei metro line 3 between Shihe road station and Qingxi road station,the key scientific problems of ground subsidence and vibration induced by subway shield construction were studied by means of field measurement and the FEM numerical simulation.The field measurement included the measurement of shield vibration source and the collection and analysis of the ground subsidence monitoring data during the shield construction.The numerical simulation part included the simulation of tunneling process and free field vibration induced by the subway shield construction.Taking the field monitoring data of typical section as reference,according to the actual engineering situation and soil parameters,the 3D FEM simulation of the tunneling process was carried out.The techniques of deactivate and reactivate element was applied to simulate the characteristics of excavated soil during the tunneling process.The distribution law of surface subsidence and the influence of factors such as tunneling speed and grouting pressure were analyzed and verified by the field monitoring data.The effective measures to control the surface subsidence were put forward.By the field measurement,the time history curve of vibration source was obtained.The amplitude and the frequency characteristics were analyzed.Taking the time history curve of vibration source as input,A 2-D FEM model was established to calculate the ground vibration induced by the subway shield construction.The results of the vibration acceleration were analyzed and the Z vibration level was calculated by different frequency weighting curves.The influence of shield induced vibration on surrounding environment was evaluated according to specifications.