The interaction mechanism of dam-reservoir-foundation during impoundment: Case study of the Xiluodu Project, China

Clarifying dam-reservoir-foundation interactions during reservoir impoundment is fundamental to dam safety assessment. However, the internal dynamics and spatiotemporal evolution of these interactions remain elusive due to multifactorial complexities. To investigate the interaction mechanism in the dam-reservoir-foundation system during impoundment, a feedback-driven dynamic double-displacement boundary method is developed based on observed large-scale irreversible translational deformation phenomena in reservoir banks, implemented within a nonlinear finite element framework. Subsequently, real-time dynamic numerical simulations of the Xiluodu Project incorporating actual impoundment schedules and dam construction sequences are conducted. The results show that the simulated and monitored deformation behaviors of the dam-reservoir-foundation system exhibit good agreement. Valley contraction is primarily driven by large-scale mountain translational deformation, while fluctuations in reservoir water level induced characteristic oscillations in the near-dam valley deformation curves. Reservoir water pressure causes foundation settlement, whereas sustained valley contraction induces foundation uplift. Dam crest displacement shows clear water-level dependency, and valley contraction caused abutment compression, which drives upstream-directed displacement of the arch dam. These two effects exhibit linear superposition behavior. This study provides critical insights for the safety assessment of high arch dams.