Abstract：Mining subsidence of mines is a procedure of re-distortion and re-damage of rock mass with all kinds of cracks under the influence of mining stress；and these cracks enlarge and develop with the mining proceeds. If the original cracks in rock mass are regarded as primary damage，the enlargement and development of the cracks may be regarded as damage evolvement. Based on crack tensor in geometrical damage theory and plastic flow format of Mohr-Coulomb constitutive model in FLAC3D，a set of numerical equations of elastoplastic constitutive model of jointed rock mass with primary damage are set up. This model is developed in VC++ programming environment for FLAC3D to call it. It is compared with Mohr-Coulomb model provided by FLAC3D and validated for jointed rock mass by a uniaxial compression numerical test. Evolvement of primary damage considered for dynamic characteristic of mining engineering，a constitutive model of jointed rock mass damage due to mining is set up. This numerical model is applied to simulate underground mining under south slope of Anjialing open pit and to research surface subsidence rules and stability of the slope influenced by underground mining. Simulation results are shown as follows：movement range and distortion degree of bench surface are larger than those of flat surface；underground mining is unfavourable to slope stability for disturbing overlying slope rock mass；and the factors of safety in some slope regions are less than 1 and reach minimal values in tensile benches. Simulation results may bring forward reasonable suggestions for underground mining design and slope stability.
