Study On The Stability Of Jointed Rock Mass Based On The Numerical Manifold Method

As a major construction object in the geotechnical engineering, jointed rock mass often has a significant influence to the safety and stability of the project. Making a reasonable assessment of the deformation and strength characteristic of jointed rock mass is of great importance for the geotechnical engineering. Meanwhile, in jointed rock mass, it often contains large amount of discontinuities that are of different trend and physical properties, which causes big problems in modeling the issues by computer.The numerical manifold method (NMM) employs two sets of meshes, combining the continuous and discontinuous deformation problems into a uniform frame. As a new method, it has been applied in geotechnical engineering. But the existing NMM is limited in elastic deformation analysis, and it becomes incapable when dealing with some construction simulations, such as the excavation process. That is a main obstacle for NMM's wide spread.Based on the above consideration, a NMM program is developed in this paper first, and several improvements to the existing NMM theory are presented meanwhile. As the NMM program is capable of the nonlinear elasto-plastic analysis and has the ability to simulate the excavation process, it is used as an analytical tool for the stability analysis of the jointed rock mass.The main achievements of this paper include:1. Based on the rectangular mathematical mesh, several improvements are presented to the existing algorithm of automatically forming of cover system; establish the element matrix of 2-order displacement function.2. Present the modeling method of different constraint conditions; deduce the inertia force matrix and velocity matrix based on high order displacement.function; present the distributed contact spring.3. Add a nonlinear elasto-plastic model to NMM, and the strength analysis of jointed rock masses is carried out using the elasto-plastic NMM program.4. An algorithm that can simulate the excavation problem in numerical manifold method is proposed, making it possible for NMM to be used in a wider range.5. Two geotechnical projects that contain typical discontinuous feature are analyzed by the improved NMM, and some instructive results are obtained.