Jinping Underground Powerhouse Surrounding Rock Stability Analysis And Evaluation

The Second Hydro-electrical Power Station of Jin Ping, which is 4800MW-installed capacity, is planned to adopt the form of the underground factory building, which is formed by two large cavities. The major axis directions of the cavities are fixed up N35°E now. the cavities lie in the forth,fifth and sixth sects of Yen Tang stratum of the Triassic Period which is composed of carbonates. As a whole the rock quality of the hill is well. But because of the tectonic movements and epigene-action, joints and faults, which reduce the hardness of the rock body, have incised the rock body. Moreover, the cavities have excavated in big span and in groups, which resulted in the biggish adjust of the rock body stress and displacement, and this adjust maybe lead to destroy in rock mass. Thereby, the project can't go on or the cavities can't work normally.This paper adopt the systemic geology engineering technique that start with the factor analysis of mechanics effect of rock body, find out the regional geological structure environment, develop the rock mass type research and crack statistic detailedly, the rock mass which decide the stability of the rock body contains of rocks and discontinuities. After obtaining above-mentioned materials, According to the corresponding hierarchical methods, we can achieve the individual rock mass quality at different levels determinately or probably. Based on the simplified geology structure, Stability of potential blocks at different constructional position surrounding rock mass is calculated and sensitivity to influencing factors of the blocks in surrounding rock mass is analyzed using software SASW, and influence of blocks on regional stability analysis and assessment of surrounding rock mass of underground seepage tunnels is synthetically evaluated. At the same time, we use the three-dimensional finite element numerical modeling technique to simulate the course of excavation, which can analyze systematically the features of stress filed, displacement and plastic zone in the surrounding rock mass of the underground cavities. The main results can be taken as the basic data and the theoretical proofs to evaluate cavities stability and guide the correct excavation.