Abstract: The stability of the left bank slope at Baihetan hydropower station is especially important in the construction and operation periods, due to the influences of the dislocation interfaces with a slightly-inclined angle and NW directional faults. In this study, the quasi-three-dimensional numerical model was established by using the realistic failure process analysis (RFPA3D) software with the arch axis profile as an example. Then the stress distribution field and displacement field of the left bank slope were studied during excavation unloading process, and the rock failure mechanism was revealed. In addition, this study analysed the initiation, propagation, extension and interaction mechanisms of microcracks during the progressive failure process. By combining with the distribution of microseismic events during excavation unloading and stress adjustment on the left bank slope, the potentially dangerous parts of the engineering were delineated, and the possible failure modes of the slope were explored. The results showed that the safety factor of the slope after excavation was 1.33 calculated with the centrifuge loading method. It was found that the most obvious deformation and failure of the slope surface were controlled by the inclined dislocation interfaces. Meanwhile, the wedge-shaped sliding within a small scale played a dominant role in the damaged zone. This study provides references for the later construction of the left bank slope and practical guidance for constructing similar rock slopes.

Key words: rock slope, microseismic monitoring, stability, numerical simulation, Baihetan hydropower station