Research on Stability for the Surrounding Rock of Underground Excavations in Different Yield Criteria

According to the failure characteristics of surrounding rock after excavation, the indexes, such as the influence degree of the shear, tension crack, compression failure, unloading, disturbance and so on, are proposed to evaluate the failure characteristics. These indexes can not only describe reasonably the different failure characteristics of surrounding rock mass of underground opening under excavation, but also effectively reflect the destruction causes of cracking, unloading, stress concentration and disturbance accumulation of surrounding rock. So, a good quantitative basis of the stability evaluation is provided in excavation of underground chambers and tunnels. The excavation process of Laxiwa Underground Powerhouse is analyzed in this paper with three plastic yield criteria : D - P, M - C and Z - P yield criteria. The influences of different yield criteria to the stability of surrounding rock are verified based on the indexes of surrounding rock failure. At last, the rationality of different yield criteria adopted in respect to different lithology is demonstrated according to the comparison of monitoring data in construction and excavation.