Study on the influence of faults in foundation on the long-term stability evolution of high arch dam

ABSTRACT: Dam foundation failures have a significant impact on the long-term stability of arch dams and threaten the safety of dams. This paper proposes a method to analyze the long-term stability evolution of high arch dams and their foundations. First, the overall stability is evaluated by the energy dissipation rate, and the weak zones could be determined according to the spatial distribution. Secondly, the multi-grid method and the vector sum method are used to calculate the safety factors of the key sliding block and to obtain their sliding stability evolution law. This method is applied to an arch dam project in southwest China, which is still in the design stage. In the absence of monitoring information, this method allows for the search for weak zones in foundations and provides recommendations. The numerical calculation results show that the arch dam and foundation have been stabilized after five years of water storage, but there are still some weak regions with concentrated energy dissipation rate. After 30 years of impoundment, the safety factors of key sliding blocks L and R on the dam abutment are 2.08 and 4.17, respectively. In general, the arch dam is safe and stable, but the weak area is the F1 fault in left abutment, which requires more attention about its deformation development process.