Abstract:A numerical method is developed for simulating failure and propagation of muitiple cracks based on man2 ifold method. For st ructures with large number of joint s , the Mohr2Coulomb law is used as the criterion of failure. The developed method permit s crack not only to propagate along original discontinuities but also penet rate through the mass medium. For propagation of individual crack , the st ress intensity factor can be accurately computed by the combination of the author2developed second2order manifold method with local sub2region BEM. The criterion of crack propagation is made according to the theory of f racture mechanics. A simulation method for crack propaga2 tion f reely through meshes is developed. It is shown f rom computational examples that the reasonable result s can be obtained by the developed method.