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Abstract The problems including support design，construction control and overall stability of surrounding rock are very serious in the underground caverns of Jinping I hydropower station. The unloading deformation and failure characteristics of surrounding rock under the conditions of high stress and low strength stress ratio have been clearly shown during the excavation. According to the mechanical characteristics of layered rock，the initial stress field and mechanical parameters of layered rock are obtained by inversion analysis considering the unloading mechanical evolution of layered rock and its numerical simulation method. Based on these，the three- dimensional numerical simulation for the underground caverns of Jinping I hydropower station is carried out；and some opinions of surrounding rock stability and support safety under high stress are obtained. The right engineering control suggestions including stress release control，capacity control of damaged zones and deformation cracking control，and so on，are put forward. The results show that the rationality of raised opinions and proposed control measures are confirmed by in-situ monitoring results of underground caverns and stability status of surrounding rock. It is shown that the proposed layered rock constitutive model and its numerical simulation method can reflect favorably the working behaviors of layered rock mass in the construction of large underground caverns in condition of high stress.
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Received: 09 March 2011
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2011, Vol. 30 
