The Stability Evaluation Of Surrounding Rock In Underground Engineering Based On 3D Elasto-plastic Structural Analysis Of ANSYS

Great progresses have been achieved on stability research of surrounding rock of underground engineering in the fields of theory studies, engineering applications and so on. However, due to the particularity and complexity of rock mass, safety hazards can't be effectively predicted yet. Therefore, it's necessary to do further research on this subject. This paper discusses the stability evaluation of surrounding rock based on 3D elastic-plastic structural analysis of ANSYS. After comprehensive review of the present advance on stability research for surrounding rock in underground engineering, essential principles of 3D elastic-plastic structural analysis of FEM have been briefly introduced. Additionally, the program structure and elasto-plastic analysis process of ANSYS are presented. Taking the stability evaluation for stopes as an example, a 3D numerical model is developed and analyzed by elasto-plastic FEM with ANSYS,and the laws of stress activities during deep mining are successfully simulated. Based on the results of numerical calculation, the stability of surrounding rock and the reinforced concrete isolation layer is evaluated. The research can contribute to design and construct underground engineering, and can be a reference to evaluate stability of surrounding rock masses in related fields.The main conclusions in this paper are as follows:(1) It's feasible and convenient to simulate the opening process of underground engineering by the large general programme of ANSYS. The powerful functions of ANSYS ensure to build a large and complicated 3D model successfully, realize the automatical partition of finite element model, guarantee the precision of calculation and read results conveniently.(2) According to the results of numerical calculation, the surrounding rock of the stopes is stable when the filling method is adopted. However, there still parts of them become unstable.(3) According to the results of numerical calculation, the boundary conditions of the 3D numerical simulation are appropriate, and the region affected by the mining activities is almost no more than 150m in horizontal.(4) The results of numerical calculation for simulating the ledge opening and stope contemporaneous filling indicate that: the value of stress in reinforced concrete isolation layer increases with the deep mining continues. There is a large-scale plastic zone in reinforced concrete isolation layer when the ledge opening and stope fill reaches the altitude of +200m.(5) The calculation also reveals that the value of stress in surrounding rock increases with the deep mining continues. Because there is a higher stress zone in the northwestward and southeast of ore, it can be predicted that there will be more violent earth stress activities.(6) The exploitation activities under +200m almost don't affect the reinforced concrete isolation layer of +230m, the increase of plastic zone and stress when the filling method is adopted.