Abstract: Brittle rock mass generally reserves high strain energy under high ground stress condition. As it is excavated, rock burst will take place as a rapid release of the reserved strain energy. The rock burst is a hackneyed type of power unstable geologic hazard, which immensely threatens the builder and equipment safety. As a major construction of the Jinping II hydropower station on the Yalong River, deep water transfer tunnels face the problems of rock burst in hard rock under high geostress. According to the characteristic of the rock burst in Jinping II hydropower station, the method of preventing the rock burst by rapid releasing stress is put forward; and the scheme of inclined radiation blasting hole is selected through numerical simulation. The numerical simulation results show that the method can make the initial stress of rock mass rapid unloaded and the stress concentration area transferred to the deep place of rock mass. Through the testing and application in water transfer tunnels of Jinping II hydropower station, sonic wave testing has been applied to verify the effect of rapid stress releasing scheme; it turns out that the method of preventing the rock burst by rapid stress releasing is validated. The research results provide theoretical foundation and ways for preventing the rock burst in similar projects.

Key words: Jinping II hydropower station, deep tunnel, rock burst, stress release