Analysis of Features and Causation of Rock Burst of Qirehataer Diversion Tunnel

Rock burst will happened when the underground engineering is excavated in the hard and brittle rock mass because of high in situ stress or concentrated stress. The length of Qirehataer diversion tunnel is 15.639km,and the maximum over-depth is 1720m. With excavation of tunnel, lightly to moderate rock burst had taken place in 600m length about of tunnel, and moderate rock burst locally. The mainly lithology of tunnel is gneiss granite and the percent is 64.5%, uniaxial compressive strength of which is 63.5MPa so it should be classified hard rock. The maximum principle stress is 30MPa in the place of rock bust. This paper analysis engineering geology conditions of this area and the characters of rock burst, author concludes that posteriority and continuity for time and Traceability and continuity for place are different from others rock burst examples. The reason is that course of stress adjustment is continually and repetitive.