基于地脉动H/V谱比卓越周期的场地类别划分  

Site classification based on predominant period of microtremor’s H/V spectral ratio

作　　者：师黎静[1] 刘佳轩 陈盛扬 SHI Lijing;LIU Jiaxuan;CHEN Shengyang(CEA Key Lab of Earthquake Engineering&Engineering Vibration,Institute of Engineering Mechanics,China Earthquake Administration(CEA),Harbin 150080,China;School of Civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]中国地震局工程力学研究所地震工程与工程振动重点实验室,哈尔滨150080 [2]同济大学土木工程学院,上海200092

出　　处：《振动与冲击》2022年第13期34-42,51,共10页Journal of Vibration and Shock

基　　金：国家重点研发计划项目(2018YFC1504601);国家自然科学基金面上项目(51978635)。

摘　　要：基于地脉动卓越周期的场地类别划分方法具有简单经济快捷的特点,包含抗震设计规范(1964)在内的多个历史版本规范与手册都曾给出过相应的划分标准。而现行抗震设计规范(2016)已对覆盖层厚度和等效剪切波速等场地类别划分指标进行了修正,这些对应于历史版本规范的划分标准也已无法继续应用;同时,国内外最新研究也表明,相对于早期划分标准中使用的水平向傅氏谱卓越周期,地脉动H/V谱比的卓越周期能更有效表达场地动力特性。通过对不同类别场地上的地脉动单点三分向观测及H/V谱比分析,研究了地脉动H/V谱比卓越周期与场地类别的对应关系,建议了一套适于现行抗震设计规范场地类别的地脉动卓越周期划分方案。其中,Ⅰ类、Ⅱ类、Ⅲ类和Ⅳ类场地对应的卓越周期范围分别为:T≤0.08 s,0.08 s<T≤0.55 s,0.55 s<T≤0.95 s和T>0.95 s。通过与基于数值模拟、理论计算及震前背景噪声等方法的对比说明了该方案的合理性。结果表明,该方案相比基于傅氏谱法的方案有很大改进,依据现行规范标准判定场地类别的准确率平均达到72%以上,略偏保守。The site classification method based on microtremor predominant period is simple,economical and fast.Many historical codes and manuals including the code for aseismic design(1964)have given corresponding classification standards.In the current code for aseismic design(2016),site classification indexes,such as,overburden thickness and equivalent shear wave velocity have been modified,these classification standards corresponding to those in historical versions of codes can no longer be appliable.Furthermore,the latest studies at home and abroad show that compared with horizontal Fourier spectral predominant periods in early used classification standards,predominant periods of microtremor H/V spectral ratio can more effectively express site dynamic characteristics.Here,based on the single point 3-direction observations and H/V spectral ratio analysis of microtremor on different types of sites,corresponding relations between predominant periods of microtremor H/V spectral ratio and site classification were studied,and a set of classification schemes of microtremor predominant periods suitable for the site classification in the current aseismic design code was proposed.The results showed that with this scheme set,the corresponding predominant period ranges of class I,class II,class III and class IV sites are T≤0.08 s,0.08 s<T≤0.55 s,0.55 s<T≤0.95 s and T>0.95 s,respectively;compared with the methods based on numerical simulation,theoretical calculation and background noise before earthquake,the proposed scheme set is reasonable;it is greatly improved compared with schemes based on Fourier spectrum method;with this scheme set,the average correctness rate of judging site classification according to the current code and standards is more than 72%,and slightly conservative.

关 键 词：地脉动 H/V谱比 场地类别 卓越周期 

分 类 号：TU413.5[建筑科学—岩土工程]