A Seismic Wave Oblique Incidence Method and the Application in Gravity DAM Seismic Research

The incidence of seismic wave is generally assumed to be vertical in seismic analysis of large-scale hydraulic structures, but during some near-field earthquakes, the direction of seismic waves is at certain angle to the ground. The non-uniform motion produced by oblique incidence can significantly affect the structures. In this paper, based on the theories of wave motion an oblique P-wave and SV-wave incidence method based on viscous-spring boundary was introduced into finite element analysis, which can accurately simulate the incidence at different oblique angles. Then the proposed method was applied in seismic analysis of a gravity dam located in southwest China. The seismic responses under oblique incidence of P-wave and SV-wave at different oblique angles were discussed. The results indicated that the seismic response was obviously influenced by the oblique incidence, and the traditional vertical incidence was unsuitable for some near-field earthquakes. The oblique incidence should be considered in the seismic analysis of high dams as well as other large-scale water-retaining structures located in seismic regions.