Research on Optimization Method for Underground Cavern Excavation

Base on elasto-plastic finite element method (FEM), the excavation methods for underground caverns are researched and optimized. The plastic dissipated energy of surrounding rock is presented as a general factor to judge the rock stability. The more plastic dissipated energy is produced, the more the surrounding rock is disturbed by the excavation, the worse the stability of the rock will become. Furthermore, the volumes of cracked zone, the plastic zone and the rebound zone of rock are also important criterions to evaluate the advantages and disadvantages of different excavation methods. Afterward, the proposed method of excavation is applied in Changheba Hydropower Project. The results of numerical computation show that the excavation time of the upper part of the surge chamber will influence the whole surrounding rock stability. The proposed method provides an effective way for the optimization analysis of underground cavern excavation.