Abstract：The mechanical properties of jointed rock masses are dominantly controlled by the joints. The joints may slip or open subjected to seismic load. When there exists a free surface，jointed rock masses will behave highly nonlinear with large deformation. Under ground excavation，the surrounding rock mass may be under stable condition in the environment of in-situ stress，but it may lose its stability when subjected to seismic load. The mechanical behaviors of the inclined jointed rock masses during excavation and under earthquake load are simulated by using discontinuous deformation analysis(DDA). Two improvements for excavation and lining are developed and implemented into the original DDA program，and the process of the tunnel excavation and earthquake response are simulated by using the advanced program. The whole failure process of the surrounding rock mass is simulated，which is of help to understand the mechanism of deformation and failure of underground excavation in jointed rock masses. These results suggest that the advanced DDA can be applied to the process simulation of the tunnel excavation and the failure process of the surrounding rock mass under earthquake load.
