层状场地中透镜体对地震动影响的基本规律

On the effect of a lenticle in a layered site on ground motion

本文采用有限元方法研究层状场地中透镜体对地震动影响的基本规律,分析层状场地与均匀场地的差别、含透镜体场地与不含透镜体场地对地震动影响的差别,以及透镜体埋深、宽度、厚度、刚度和输入波频谱等因素对地震动反应谱的影响。研究表明,层状场地与其等效的均匀场地有着显著的差别;透镜体的存在对地震动有显著的放大作用,该放大作用可达93.5%;由于入射波在透镜体周围的散射,会产生竖向加速度,且竖向加速度的短周期成分相对较多;透镜体埋深、宽度、厚度、刚度以及输入波频谱等因素对地震动反应谱具有重要的影响。

This paper investigates the effect of a lenticle in a layered site on ground motion by using finite element method, and discusses the difference between the layered site and the equivalent homogeneous site, and the difference between the layered site with a lenticle and its free field, and the effects of the lenticle＇ s depth, width, thickness and stiffness and the incident wave spectrum on the ground motion. It is shown that there is significant difference between the layered site and the equivalent homogeneous site, a lenticle can significantly amplify the ground motion and the amplification can be 93.5% larger than the free-field response; due to scattering of the incident waves there exists vertical acceleration with more short-period contents; lentiele＇ s depth, width, thickness and stiffness and the incident wave spectrum have great effects on the ground motion.