Seismic Analysis of Gravity Dam-Layered Foundation System Subjected to Earthquakes with Arbitrary Incident Angles

Seismic performance of gravity dams has been widely concerned due to their importance in hydraulic engineering. In recent years, the influence of the incident angle of seismic waves and the inhomogeneity of complex foundation on the soil-structure interaction (SSI) system has become a focus. However, the foundation is often simplified to homogeneous elastomer when simulating nonuniform excitation seismic wave propagation due to the complex theoretical formulations. Therefore, this paper considers the stratification of foundation and analyzes the dynamic response of a gravity dam under obliquely incident seismic waves. First, the gravity dam-layered foundation interaction system is established in the finite-element software, and the concrete damage plasticity (CDP) model is adopted of the dam. Then, the displacements of the foundation under seismic P or SV waves with arbitrary incident angles are calculated by combining the one-dimensional time-domain method and the free wave field calculation method. Finally, adopting the wave input method based on the substructure of artificial boundaries, the seismic waves are converted to equivalent nodal forces on the viscous-spring boundaries of the layered foundation. Furthermore, the dynamic response of the dam on the homogeneous foundation is also simulated for comparison in this paper. The calculation results confirm that the impact of arbitrary incident angle of earthquakes and the parameters of foundation on the dam response is significant, and both should be considered comprehensively.