Abstract

With the increasing in the number and expanding the scale of underground engineering in China, increasingly prominent on rock burst disaster. Rock burst is one of the most serious geologic hazards, adversely affecting the safety, economy and productivity of underground engineering construction. High ground stress and its induced frequent rock bursts are major influences of tunnel instability during the survey and design and construction stages. As a major construction of the Jinping II Hydro-power Station on the Yalongjiang River, the deep-buried water transfer tunnels face the problems of rock bursts in hard rock under high geostress. According to the characteristic of the rock bursts in Jinping II Hydro-power Station, the method of preventing the rock burst by rapid stress releasing was put forward. Furthermore, the slit local stress relieving method on the key parts of the wall rock of excavation unloading zone is adopted, the two-dimensional stress state on rock wall can be determined provided gouging of more than 3 narrow slots of different directions on the measured site and measuring the deformation caused by the gouge. The test result shows that the wall rock of underground cavern under various influence factors of blasting load and stress field adjustment of rock mass after blasting, dynamic unloading effect of rock mass is significant. Through the testing and application in water transfer tunnels of Jinping II Hydro-power Station, the rapid stress release method by blasting has proven to be an effective method for preventing and treating rock burst.

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