Distance effects of the fault on the surrounding rock mass stability of the main powerhouse at the Huanggou pumped-storage power station

Abstract

The distance between the fault and the underground cavern affects the surrounding rock mass stability, which is of great importance to the design and construction of the large-scale underground cavern especially the underground powerhouse. This study focuses on the distance effects of the fault on the rock mass stability of the main powerhouse at the Huanggou pumped-storage power station. Firstly, a microseismic monitoring system was constructed to investigate the distribution and mechanism of distance-dependent damage of the surrounding rock masses of the main powerhouse. Then, the rock failure process analysis and strength reduction method (RFPA-SRM) was adopted to reproduce the failure processes of the surrounding rock masses of the main powerhouse at different distance to the fault f34. Finally, by comparing the numerical simulation results with microseismic monitoring results, the distance effects of the fault f34 on the damage mechanism and failure modes were discussed. It can be concluded that when the distance is low, the damage of the surrounding rock masses subjected to excavation evolved from the spandrel toward the fault, eventually causing a V-shaped collapse if the strength reduction continues. As the distance increases, the effects of the fault on the damage mechanism and failure modes are reduced and the safety factor of the underground cavern is improved. The findings are expected to provide references for evaluating the surrounding rock mass stability of an underground powerhouse under complex geological conditions.