考虑不同影响因素的珊瑚岛礁场地地震响应分析

Seismic response analysis of coral island reef site considering different influencing factors

珊瑚岛礁场地在强地震条件下的稳定性是开展基础设施建设的首要挑战,而由于珊瑚岛礁海洋工程地质以及钙质砂动力特殊性,系统而深入地研究强震条件下珊瑚岛礁动力响应是进行场地地震稳定性评价的关键。文中基于UPFs在ANSYS软件中嵌入了模拟远场辐射阻尼和珊瑚砂非线性动力特性的用户子程序,建立了珊瑚岛礁场地地震响应分析时域计算模型,进而分别考虑地震动、相对密实度和有效围压3种因素,从加速度放大特性、加速度反应谱、加速度峰值变化以及相对位移等方面探究不同因素对珊瑚岛礁场地地震响应的影响规律。计算结果表明:珊瑚岛礁场地对长周期频谱有滤波作用,相对密实度和有效围压对岛礁场地的地震响应有一定影响,所建立模型表现出良好的适用性。

The stability of coral island reef sites under strong earthquakes is the primary challenge for infrastructure construction.Due to the marine engineering geology of coral islands and reefs and the dynamic characteristics of calcareous sands,systematic and in-depth study of the dynamic response of coral islands under strong earthquakes is the key to the evaluation of site seismic stability.A time-domain model for seismic response analysis of coral island reef sites is established using the user subroutine embedded in ANSYS software based on UPFs for simulating far-field radiation damping and nonlinear dynamic characteristics of calcareous sand.Furthermore,considering three factors of ground motion,relative density and effective confining pressure,the influences of different factors on the seismic response of coral island reef sites are explored from acceleration amplification characteristics,acceleration response spectrum,acceleration peak changes and relative displacements.The calculation results show that the coral island reef site has a filtering effect on the long-period spectrum,and the relative density and effective confining pressure have a certain impact on the seismic response of the island reef site.In addition,the established model shows good applicability.