地铁致地表振动局部放大现象实测与机理分析  

In-situ measurement and mechanism analysis for Local amplification phenomena of metro induced ground-borne vibration

作　　者：宗刚[1,2] 张永红[1] 任晓崧[1] 

机构地区：[1]同济大学土木工程学院结构工程与防灾研究所,上海200092 [2]同济大学土木工程防灾国家重点实验室,上海200092

出　　处：《振动与冲击》2017年第9期247-252,共6页Journal of Vibration and Shock

基　　金：上海市自然科学基金基础(13ZR1444800)

摘　　要：地铁运行引发的地表竖向振动并非单调递减,存在局部放大现象。对上海3处典型的埋置地铁行经场地进行了地表振动实测,实测结果表明,各场地地表振动的衰减曲线均存在局部放大区,第一局部放大区(主放大区)最为显著,位于1倍埋深的振中距(地表与振源投影点距离)附近。基于弹性波场理论,辅以有限元数值模拟,分析主放大区的主要影响因素有:(1)近场体波在地表入射与反射的叠加效应;(2)入射波在场地内的行程差导致的衰减率不同;(3)地铁运行引发的场地弹性波场不均匀分布特征。因素(1)和因素(2)主要作用于剪切波分量以影响主放大区的出现位置,因素(3)对纵波和剪切波均有较大影响,入射波场的剪切波分量较纵波分量越占优,主放大区现象就越显著。The surface vertical vibrations induced by metro do not decay monotonously. There is a region called the local amplification region (LAR) with an offset to the epicenter. In-situ vibration measurements were conducted at three representative sites passed by buried metros. The results showed that there are LARs for each vibration attenuation curve of 3 sites; the first LAR defined as the major amplification region (MAR) is the most siginificant and appears with a distance of about one burial depth from the epicenter; base on the theory of elastic wave propagation and numerical simulation of finite element, the major influence factors on the MAR are (1) the superposition effect of incident and reflected waves within the near filed region (2) the different attenuation rates of incidents due to different traveing distances (3) the non-uniform wave field distribution characteristics induced by metro; the factor (1) and (2) act on shear wave components to affect the position of the MAR; the factor (3) acts on both shear and longitudinal waves; the more the shear wave components than the longitudinal ones, the more remarkable the MAR phenomenon. © 2017, Editorial Office of Journal of Vibration and Shock. All right reserved.

关 键 词：地铁 场地振动 振动衰减 局部放大 

分 类 号：U231[交通运输工程—道路与铁道工程]