层状半空间中洞室群对地震动的时域放大作用

采用间接边界元法和频域变换方法研究了层状半空间中洞室群对地震动的出平面时域放大作用,并以天津地区典型场地为例分析了洞室间距和入射地震动频谱对放大作用的影响。研究表明,洞室群对地震动的放大作用非常大,与自由场相比,地表加速度峰值放大32.1%,地表加速度反应谱峰值放大85.2%,洞室群对地震动的频谱也有明显影响;洞室间距越小,洞室之间的相互影响越大,对地震动的放大作用越大。研究对于地铁沿线设计地震动的估计具有参考价值。

Time-domain amplification of seismic ground motion by group cavities in layered half-space

This paper studies time-domain out-of-plane amplification of seismic ground motion by group cavities in layered elastic half-space using indirect boundary element method and time-frequency domain transform,and discusses the effects of cavity interval and incident seismic wave spectrum on the amplification,taking typical site in Tianjin district as an example.It is shown that,group cavities have significant amplification to seismic ground motion,and compared with the free field,surface acceleration peak and its response spectrum peak can be amplified by 32.1% and 85.2%,respectively,and group cavities also have influence on spectrum of ground motion.The smaller cavity interval will result in larger interaction between cavities,and larger amplification to seismic ground motion.This study is valuable for the evaluation of design seismic ground motion along underground Metro lines.