Numerical Analyses and Elasto-Plastic Behavior Study on Surrounding Rock Mass of the Underground Caverns in a Hydropower Station during Deep Excavations

For the time being in China, aggressive development of the western hydroelectric resources is being performed. Taking the Shuangjiangkou (SJK) Hydropower Station as an engineering background, the elasto-plastic behavior is studied on the surrounding rock mass of the underground caverns, including the main powerhouse, the transformer house, the surge chamber, the busbar chamber, etc. in the whole process of deep excavations. A 3D numerical simulation is performed using FLAC^3D. Four typical yield criteria which are Mohr-Coulomb (MC) criterion, Drucker-Prager model for the outer adjustment (DPO), Drucker-Prager model for the inner adjustment (DPI) and Zienkiewicz-Pande criterion (ZP) are all utilized in the elasto-plastic behavior study on the surrounding rock mass of the underground caverns. Among of the criteria, ZP criterion is written in the VC++7.1 compiling environment and the other three criteria are included in FLAC^3D. The displacement field of the surrounding rock mass are obtained and compared under the four criteria in the process of excavations. The plastic zones are also obtained and compared in this paper. It is concluded that the results obtained through MC and DPI criteria are much greater than those obtained by the other two criteria, and the results obtained though ZP criterion are close to the practical engineering results.