Of Epb Shield Tunneling-induced Surface Subsidence Analysis And Numerical Simulation

Forecasting and controlling the ground settlement induced by excavation is very important in constructing city subway tunnel with shield driven method. Combing with shield tunneling practice of Nanjing subway, on the basis of field measuring and testing, theoretical analysis and numerical simulation, this thesis makes a study on the behavior of ground settlement induced by tunneling. The main research results are as followings:1. The mechanism of ground settlement is discussed based on analysis of the geometrical effects and mechanical effects of EPB shield construction.2. On the basis of monitoring data, and considering tunnel depth, geological condition, opening parameters and other influential factors, the characteristics of soil deformation induced by EPB shield tunneling in the interval tunnels from Xuanwumen to Xufuxiang and from Xufuxiang to Nanjing railway station in Nanjing No.1 Subway are analyzed in this thesis. Then the development process and distribution of the ground settlement are obtained.3. Using the monitoring data, it studies into the main influential factors on the ground settlement, such as earth pressure in the cutter chamber, routing parameter and slag tapping control. It also discusses several construction faults caused by setting inappropriate construction parameters and achieved many useful conclusions.4. Using 3D Fast Lagrangian Analysis of Continua, FLAC3D with Drucker-Prager yield criterion, a 3-D numerical simulation of the wholly shield excavation process of the interval tunnel from Xufuxiang to Nanjing railway station is carried out, during which the factors of tunnel depth, groundwater level, shield machine, ground loss, earth pressure in the cutter chamber and grouting pressure have been considered.