Seismic response analysis of the reef-seawater system under incident SV wave

Abstract

The seismic response analysis of a reef engineering site is the foundation for the seismic design of artificial islands and other upper constructions. This study proposes a two-dimensional seismic analysis model for the reef-seawater system, where the fluid-solid coupling effect is considered and the wave radiation effects of infinite fluid and solid domains are simulated by corresponding artificial boundary conditions. Meanwhile, the seismic wave input method based on the substructure of artificial boundaries is modified to accomplish the process of inputting the seismic waves with arbitrary incident angles into the calculation region. The accuracy of the proposed model is verified by numerical examples. Afterwards, we conduct the parametric studies and the seismic analysis of a series of practical layered reef models. The results indicate that the least favorable slope gradient for the seismic response is generally at approximately 30°, and the feature of wave velocity reduction along the vertical direction significantly magnifies the seismic response on the reef flat. The peak acceleration ratio near the edges of the reef flat distributes between 3 and 4. While in the middle area, it is usually between 1.5 and 2.5, and can reach up to 4 when the width of reef flat decreases.