Study On The Pridiction And Prevention Of Rockburst In The Diversion Tunnel Of Jinping Ⅱ Hydropower

The prediction and prevention of rockburst are the key problems of engineering geology in deep lying tunnel of brittle rockmass and need to be quantizing studied systematically. With the development of engineering construction, these problems are more necessary and important than before.This paper studies the Jinping II Hydropower Station. Reference to the former achievement, using system analysis and being based on geomechanics, mechanism, prediction and treatment are researched.Large number of datum of the uniaxial compressive strength of rock have characteristic of Weibull probability distribution. Based on the parallel poles model of statistic mechanism, the constitutive equation of the brittle rock is deduced and the theoretic curve and test curve fit well. Compared to typical deforming curve of brittle rock, a conclusion is obtained that mechanism of rockburst is a process of damage developing and strain energy releasing, and intensity of rockburst is correspondence to the evolution of damage variable and damage energy release rate.Based on the statistic damage mechanism of rockburst, a probability model which can reflects the principal regularity of tunnel's rockburst is deduced and it can predict the probability of rockburst intensity of all levels under the different crustal stress. The factual rockburst of the exploratory shows that this prediction model is available. By geology comprehensive analysis, probability model and neural network predict the rockburst intensity which probably happens in different segment of Jinping diversion tunnel and the three results are generally accordant. The length of different rockburst intensity of every segment of diversion tunnel is predicted according to the probability model.By finite element method (FEM) research on bolting, rockbolt play the role of preventing crack development and stress transfer to deep-seated rockmass. Reducing the spacing between of bolts has a better effect to prevent rockburst than lengthening bolts. The hole for release of stress is an effective method to prevent heavy rockburst because it make the stress transfer to deep-seated rockmass effectively.