三种非线性时变识别方法的对比研究——以2021年日本福岛地震为例  

Comparative study on three identification methods of the nonlinear time-varyin process:a case study of the 2021 Fukushima earthquake in Japan

作　　者：陈长龙 刘启方 CHEN Changlong;LIU Qifang(Suzhou University of Science and Technology,Suzhou 215011,Jiangsu,China)

机构地区：[1]苏州科技大学,江苏苏州215011

出　　处：《地震工程学报》2023年第2期372-381,共10页China Earthquake Engineering Journal

基　　金：国家自然科学基金项目(51978434)。

摘　　要：利用2021年日本福岛地震(M_(JMA)7.3)中6个KiK-net台站的观测记录,分别基于移动窗解卷积法、移动窗谱比法和移动窗自相关函数法对场地非线性时变过程进行研究,分析非线性发生的阈值和程度。研究表明:三种方法识别场地非线性时变特征的稳定性不同。移动窗解卷积法更容易获得较为稳定的土体非线性时变过程,但其反映的是地表至井下平均波速的变化,识别的非线性程度偏低。对于存在强波阻抗比的浅表层土体,移动窗谱比法和移动窗自相关函数法识别的非线性程度更强;对于较低波阻抗比的浅表层土体,则不容易识别出稳定的非线性时变结果。三种方法识别的非线性最强时刻基本一致,皆位于整条记录加速度峰值附近。基于三种方法识别的6个台站的非线性阈值约在40~140 gal,剪切波速下降比在16%~53%之间,场地非线性程度较明显。Based on the records of six KiK-net stations in the 2021 Fukushima earthquake(M_(JMA)7.3),the nonlinear time-varying process of the site was studied using the moving-time-window deconvolution method,moving-time-window spectral ratio method,and moving-time-window autocorrelation function method.Then,the threshold and degree of nonlinearity were analyzed.Results show that the ability of the three methods to identify the nonlinear time-varying characteristics of the site differs.The moving-time-window deconvolution method can easily obtain a more stable nonlinear time-varying response for soil,but the degree of nonlinearity is low.The method reflects the change of average wave velocity from the surface to the underground.For shallow soils with a strong wave impedance ratio,the nonlinear degree of identification results derived from the moving-time-window spectral ratio method and moving-time-window autocorrelation function method are strong.These two methods cannot provide stable nonlinear time-varying results of shallow soils with a low wave impedance ratio.The strongest nonlinear moments identified by the three methods are basically the same and are located near the peak acceleration of the whole record.The nonlinear threshold values of the six stations identified by the three methods are about 40-140 gal,and the shear wave velocity drops between 16%and 53%,indicating that the degree of site nonlinearity is high.

关 键 词：移动窗解卷积 移动窗谱比 自相关函数 场地非线性 时变 

分 类 号：P631[天文地球—地质矿产勘探]