基于观测记录的场地卓越周期与场地基本周期对地震动放大模型的影响研究  

The effect of site predominant period derived from seismic records and site fundamental period on seismic site amplification model

作　　者：侯瑞彬 HOU Ruibin(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031

出　　处：《地震工程与工程振动》2021年第6期202-210,共9页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金项目(51578470)。

摘　　要：在评估场地对地震动的放大作用时,场地周期常被认为是一个合适的场地参数,通常将场地周期区分为场地卓越周期和场地基本周期,场地卓越周期可由地表水平竖向谱比估计确定,而场地基本周期可由地表土层物理力学参数计算得到。为探究2个参数在定量评价地震动场地放大效应时的影响,文中搜集了日本588个KiK-net和K-NET台站的场地卓越周期估计值并根据其钻孔勘察资料计算了场地基本周期值,利用4791条浅地壳与上地幔地震观测记录并结合日本基岩场地的地震动衰减模型计算得到了所选场地的放大比经验值;然后,分别以场地卓越周期和场地基本周期为参数建立场地放大模型,对比分析了2种场地周期参数对场地放大系数的影响。结果表明:二者作为场地参数评估场地放大效应时,均能很好地反映场地放大比共振效应且场地卓越周期的共振效应更显著;在0.06 s至0.9 s谱周期场地卓越周期作为场地参数时场地放大比变异性更小,而在大于0.9 s谱周期场地基本周期模型的变异性更小,其它情况下二者的变异性相近,在0.2 s至0.3 s和在大于2.0 s谱周期场地放大比变异性之间的差别在数理统计意义上显著。因此,对于钻孔资料缺失的地区,可采用场地卓越周期作为场地效应评价参数。Site period is considered as a suitable parameter for evaluation of seismic site amplification effect.The site period is usually differentiated as site predominant period,which could be estimated using the horizontal-to-vertical spectral ratios,and site fundamental period,which could be calculated by the physical and mechanical parameters of surface soil layers.To investigate the difference on evaluation of the site amplification effect between the two site period parameters,the estimated site predominant periods for 588 KiK-net and K-NET sites were collected and the site fundamental site period of the sites were computed using the borehole log data.Empirical site amplification ratios for the selected sites were calculated using 4791 ground motion records from shallow crustal and upper mantle earthquakes in Japan according to a ground motion prediction equation for rock site.Then,two site amplification models were developed using the empirical site amplification ratios with site predominant period and site fundamental period as site parameter,respectively.The effect of site period difference on site amplification ratio was analyzed.The results showed that both the two site period parameters could well capture the site resonant effect and the site resonant effect by predominant period is more significant.At the spectral period range from 0.06 s to 0.9 s,the variability of amplification ratios for the site predominant period model is smaller,and at the spectral periods larger than 0.9 s the variability of amplification ratios for the site fundamental period is smaller.Otherwise,the variabilities are close.However,the difference of the variabilities between the two models is statistically significant at spectral periods from 0.2 s to 0.3 s and larger than 2.0 s.Therefore,the site predominant period is an alternative parameter for site effect evaluation for the regions without borehole log information.

关 键 词：场地卓越周期 场地基本周期 场地放大模型 场地放大比变异性 地震动衰减模型 

分 类 号：P315.9[天文地球—地震学]