Whole failure process analysis for jointed rock masses based on coupling method of DDA and FEM

The elastic-plastic mechanical behaviour is a typical characteristic of rock mass. The load action will bring on the local destruction, large deformation, even whole failure of rock mass with the discontinuous mediums (e.g. joint, crack and fault). It is a coupling process of the continuous deformation and the discontinuous deformation. The discontinuous deformation analysis (DDA) and finite element method (FEM) are combined to build the elastic-plastic mechanical model. The rock block is divided into the finite element meshes. FEM is used to solve the displacement field and the stress field inside the block. The contacts between the deformable blocks are simulated DDA method. The parametric variational principle is derived to analyze the elastic-plastic problem with above coupling model. The theoretical calculating formulae are obtained from the variational principle. The governing equations of mechanical model are established. The proposed method coupling DDA and FEM is used to implement the simulation and analysis for the deformation process of jointed rock masses around one underground cavern. It is easy to simulate the whole process from plastic to elastic yielding failure, and to the large deformation under the condition of plastic flow or instability