Abstract: The rock mass is a king of more jointe medium with initial geometrical damage. Open and undergroung mimimg result in change of stress field, thereby joint lengthening,,damage increasing, strength decreasing. According to Kawarnoto damage tensor concept, equivalent strain principle and fracture mechanics theory, the joint damage evolution of rock mass is simulated of Antaibao coal mine under the condition of the combine mining. The damage tensor distribution was diacovered. The peak of damage degree was 0.590 after open-pit mining, and influence scope was about 30 meters.The rock mass damage of slope surface after undergroung mining wass almost not increased; The rock mass damage degree peak upon mined-out area was 0.5 ~ 0.8.

Key words: rock mass damage, anisotropic, combine mining, joint rock mass