Comparison of impounded water models for nonlinear seismic response analysis of arch dam: A case study

Simulating impounded water is a crucial aspect of the nonlinear earthquake response analysis of arch dams. This study investigates the impact of impounded water models on the nonlinear dynamic response of arch dams. Three models are considered: the Westergaard added mass model, the compressible impounded water model with rigorous dam-water-foundation interaction, and the compressible water with an approximate water-foundation interaction modeled using the absorption coefficient. The nonlinear dynamic response of the 235 m-high GX arch dam under various earthquake scenarios is analyzed as a numerical example. Concrete damage and contraction joint opening are compared across the three impounded water models. Additionally, the effect of bottom sediment is investigated by simulating it as a liquid. Results indicate that the effect of water compressibility varies from record to record. In extremely strong earthquake scenarios, water compressibility causes the dam concrete damage to shift to lower elevations compared to the added mass model. The model using the approximate absorption coefficient does not adequately capture the water-foundation interaction, while bottom sediment can be neglected when modeled as a liquid.