Analysis For Rock Mass Stress And 2D FEM Numerical Simulation For Tunnels Of Shenzhen Subway System

After tunneling, the rock mass stress is formed. It is one of the most important parameters when designing tunnels. Then it is necessary to research the rock mass stress. The principle of finite-element method is used to analyze many kinds of the underground openings. And some numerical simulations were carried out with ANSYS program. The results are compared with that coming from simplified formulas. Some knowledge has been achieved according to the calculated results of some examples. At the same time, it is pointed out that some problems should be considered in practice.In this paper, many basic ways of calculating rock mass stress are introduced and the results are figured out in the light of these ways. In the analysis of the finite-element, the material nonlinearity of rock is considered; isoperimetric element of four-node is used in the course of meshing. Drucker-Prager criterion is applied when plastic deformation is considered. Then Newton-Raphson method is used in solving process. There are lots of examples, which are analyzed in finite-element ways, and then they offer reference values for simplified formulas and judge the range of the basic ways. At the meantime, it is generalized that how the rock mass stress in shallow subway, in deep subway and shallow hill slope distribute. It is also considered that many factors, such as the shape of tunnel, the depth, cohesive strength and friction angle, can influence the stress. In addition, the project, tunnels of Shenzhen subway system, is analyzed and calculated by the way of 2D FEM numerical simulation. Due to the illegal distance of the two lines, the way of finite-element is used to work out precise results. Then it is suggested that this project is feasible and some methods should be adopted to make this project safety.