Abstract：There are lots of pore spaces，joint planes and cracks，and they are a kind of initial damage in rock mass. It is the initial damage，damage evolution and propagation fracture that result in various failure of jointed rock mass. The influence of crack propagation process and interaction of cracks on rock mass strength is systematically studied according to propagating-fracture mechanism of jointed cracks. A fracture failure strength model for jointed rock mass is established，and applied to guide reinforcement design for a high rock mass slope at Dawan oil depot in Guangdong Province. Some satisfactory computational results are obtained and remarkable economic benefits are achieved from the model.
