Abstract:The key technical problem for seismic safety analysis of coral islands is to reasonably and efficiently simulate the nonlinear dynamic characteristics of coral sand, the radiation damping of far-field infinite foundation, and the influence of hydrodynamic pressure of sea islands. Based on the characteristics of UPFs, a time-domain calculation model for analyzing the seismic response of island sites with coral sand foundation was established by using the general finite element software ANSYS. A new equivalent linear element of coral sand was created to describe the nonlinear dynamic characteristics of coral island sites, and a viscous artificial boundary element was derived and developed. Based on Westergaard's added mass formula, the hydrodynamic pressure of the channel was simulated with mass21 element, and the FORTRAN interface program was established to realize the free-field response. Furthermore, the rationality and effectiveness of the proposed model were verified by the free-field analysis of a typical coral island site. Finally, an actual coral island site in China was taken as an example, and the nonlinear seismic response of coral island sites was discussed from the aspects of surface peak acceleration and response spectrum. Thus, the dynamic response analysis of various complex island sites can be carried out by using the large-scale solution and analysis ability of ANSYS.
