Numerical Modeling on Deformation of Fractured Reservoir Bank Slopes During Impoundment: Case Study of the Xiluodu Dam

Investigating deformation behavior of fractured reservoir bank slopes during impoundment plays an essential role in safety control of high arch dams. Because of changes in water levels during impoundment, the fractures are subjected to varying water pressure and cyclic wetting-drying conditions. In this numerical study, mechanical, physical, and chemical water-rock interactions in rock fractures are incorporated into discrete element modeling of fractured reservoir bank slopes, and effects of mechanical, physical, and chemical water-rock interactions on deformation of fractured reservoir bank slopes are investigated based on a case study of valley deformation at the Xiluodu Hydropower Station. The mechanical water-rock interaction is considered by the effective stress law, while the physical and chemical water-rock interactions are modeled by some empirical deterioration laws. The results showed that the modeled and monitored deformation behaviors of fractured reservoir bank slopes are in good agreement. The slip of shear zones due to water pressure elevation and mechanical parameter weakening is the main reason of impoundment-induced valley contraction. Discrete element method considering water-rock interactions can serve as a robust and reasonable tool to predict the deformation magnitude of fractured reservoir bank slope. Mechanical, physical and chemical water-rock interactions in rock fractures are incorporated into discrete element modeling of fractured reservoir bank slopes.Four scenarios are designed to understand the role of mechanical, physical and chemical water-rock interactions on deformation of fractured reservoir bank slopes.The slip of shear zones due to water pressure elevation and mechanical parameter weakening is the main reason of impoundment-induced valley contraction.