近场地震动竖向与水平分量统计特性对比  

Comparison between the statistical characteristics of the vertical and horizontal components of near-fault ground motion

作　　者：李明珂 袁万城[1] LI Mingke;YUAN Wancheng(State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]土木工程防灾国家重点实验室(同济大学),上海200092

出　　处：《哈尔滨工程大学学报》2024年第2期230-237,共8页Journal of Harbin Engineering University

基　　金：国家重点研发计划(2019YFE0112300);土木工程防灾国家重点实验室基金项目(SLDRCE19-B-19);国家自然科学基金项目(51778471、51978512);山东省交通运输科技计划(2020B74)。

摘　　要：为研究近场地震动竖向与水平分量特性,本文对PEER数据库中1202组近场强震的地震动进行统计分析,研究了竖向水平加速度峰值比PGAv/PGAh、反应谱之比Sav(T)/Sah(T)、竖向水平峰值到达时间的特性。讨论了PGAv/PGAh与断层距、场地条件、震源机制的关系,并采用对数正态分布拟合不同场地条件、不同震源机制的PGAv/PGAh分布;对比了不同断层距、不同场地条件Sav(T)/Sah(T)的变化规律;研究了近场强震水平竖向分量峰值加速度的大小和到达时间上的相关性,并对结构分析过程中竖向地震动的选择提出建议。结果表明:断层距、场地条件、震源机制都会影响近场地震动的竖向分量,断层距小、走滑断层、场地条件差都易产生较大的竖向地震动;断层距小、场地条件差时,地震动竖向分量高频成分越强,断层距大、场地条件好,竖向地震动低频成分越强;竖向分量峰值加速度的大小与到达时间和两正交水平分量峰值加速度的大小与到达时间的几何平均数有明显的线性关系。To further elucidate the vertical and horizontal component characteristics of near-fault ground motion,1202 sets of ground motion in the PEER database were counted to statistically analyze strong near-fault ground mo-tion in this study.The characteristics of the vertical-to-horizontal peak acceleration ratio(PGAv/PGAh),vertical-to-horizontal response spectrum ratio(Sav(T)/Sah(T)),and arrival time interval between horizontal and vertical acceleration peaks were studied.Furthermore,the relationships between PGAv/PGAh and fault distance,site con-ditions,and focal mechanism were discussed.The lognormal distribution was applied to fit the distribution of PGAv/PGAh under different site conditions and focal mechanisms.Moreover,the change laws of different fault dis-tances and site conditions on Sav(T)/Sah(T)were compared.The correlation between the amplitude of peak accel-eration and the arrival time of vertical and horizontal near-fault ground motion was studied,providing advice on the selection of vertical ground motion in structural analysis.The results reveal that fault distance,site conditions,and focal mechanism influence the vertical component.Vertical ground motion with strong high-frequency content tends to be observed in stations with a smaller fault distance,slower shear wave velocity,and bad site conditions,where-as vertical ground motion with strong low-frequency content tends to be observed in stations with a larger fault dis-tance and good site conditions.An obvious linear relationship exists between the vertical component and the geo-metric mean of two orthogonal horizontal components of ground motion in the amplitude of peak acceleration and the arrival time.

关 键 词：近断层 竖向水平加速度峰值比 加速度峰值比 反应谱比 加速度峰值到达时间 断层距 场地 震源机制 

分 类 号：P315.9[天文地球—地震学]