A scaled boundary finite element method is developed for the analysis of hydrodynamic pressures acting on arch dam faces with a reservoir of irregular geometry. Water compressibility and reservoir boundary absorption are considered simultaneously. The reservoir is idealized as composed of finite and infinite subdomains. Governing equations for evaluating hydrodynamic pressures of finite fluid domain have been established and the solution procedures are presented. In addition, the boundary conditions at the interface between finite and infinite subdomains are decided. Numerical examples validate the present method with high accuracy and show that the fairly irregular geometry of a reservoir has an important influence on the hydrodynamic pressures acting on the arch dam face. Frequency response functions of the hydrodynamic pressures in the stream and cross-stream directions are evidently influenced by reservoir geometry, while hydrodynamic pressures in the vertical direction are relatively less influenced. Another feature of the frequency response function of hydrodynamic pressures is that the amplitude of resonant peaks is affected much more by reservoir geometry as compared to the resonant frequency. Besides, peak value of hydrodynamic pressures in the arch direction and cantilever direction is also significantly influenced by reservoir geometry. Based on these facts, it can be concluded that the effect of reservoir geometry on hydrodynamic pressure should be considered for seismic design of arch dams.
