CHINA MINE ENGINEERING

The deformation of roadways and stopes in the process of mining is the reflection of multiple factors such as crustal stress, tectonics and rock mass strength. Crustal stress is one of the important influencing factors. Studying the measurement results of original rock stress is helpful to comprehensively understand the distribution of crustal stress in the whole project area, and provide a basis for engineering design and mining. The method and principle of in-situ stress measurement by relief method are described. The in-situ stress measurement by relief method for two medium stage which the depth are more than 600m in the certain mine, shows that the stress field in the exploration area is dominated by the horizontal stress, and the maximum horizontal principal stress is 14.25~20.17MPa. The intermediate principal stress values were 8.34~11.35MPa, respectively. The minimum principal stress values are 5.67~8.68MPa respectively, which are vertical stresses. The direction of the maximum principal stress in the measuring area is NNE~NEE. The difference between the maximum principal stress and the minimum principal stress in each test section is large gap, and the ratio is about 2.54 on average, which will result in relatively large shear stress. R_c/σ_max is used to calculate the stability of roadway surrounding rock. For medium stage -258m, dacite porphyry and diorite rocks are of low stress and no rock burst. The deformation grade of sericite phyllite is slight. For medium stage -378m, the surrounding rock of dacite porphyry is highly stressed and prone to rock burst; Diorite belongs to low stress, without rock burst; Quartz porphyry is of high stress and medium grade of large deformation; The large deformation grade of sericite phyllite surrounding rock is slight.