Study on Slope Stability of Inlet / Outlet of Lower Reservoir of Warang Pumped Storage Power Station in Upper Yellow River

Slope instability is very common in the process of building hydropower projects in alpine canyon areas, which has an important impact on engineering construction. In this paper, the slope of the inlet/outlet of the lower reservoir of the Warang pumped storage power station in the upper reach of the Yellow River is taken as the research object. Based on the methods of adit logging and borehole TV, the rock mass structural plane is counted: Through borehole wave velocity test, unloading zoning of slope rock mass is carried out. Accordingly, the potential failure mode of the slope is qualitatively analyzed. Through UDEC software, a discrete element model of slope based on DFN discrete fracture network is established. Considering three working conditions of natural, rainstorm and earthquake, the numerical simulation of natural slope, unsupported excavation process and supported excavation process are carried out respectively to reveal the main controlling factors of potential deformation of slope. The results show that the deformation and failure of the slope are mainly controlled by two groups of structural planes: unloading fissures and gently inclined fissures along the slope. The potential deformation mode is step-like slip-crack failure. The stability study shows that the anti-sliding stability of the natural slope does not meet the specification requirements under three working conditions. In order to ensure the safety of inlet and outlet, combined with slope deformation mode and engineering experience, the corresponding excavation support scheme is proposed. The research shows that the supporting scheme is effective and feasible, which can effectively improve the slope stability and make the stability coefficient meet the specification requirements under different working conditions.