汶川地震竖向地震动衰减关系  

Vertical ground motion attenuation relationship of Wenchuan earthquake

作　　者：刘平[1] 罗奇峰[2] 陈兴周[1] LIU Ping;LUO Qifeng;CHEN Xingzhou(School of Architecture and Civil Engineering,Xi’an University of Science and Technology,Xi’an 710054,China;Shanghai Institute of Disaster Prevention and Relief,Tongji University,Shanghai 200092,China)

机构地区：[1]西安科技大学建筑与土木工程学院,西安710054 [2]同济大学上海防灾救灾研究所,上海200092

出　　处：《哈尔滨工业大学学报》2020年第2期119-128,共10页Journal of Harbin Institute of Technology

基　　金：国家自然科学基金(51808444)

摘　　要：为系统研究汶川地震的竖向地震动特征,回归出了汶川地震的竖向地震动衰减关系.在此基础上,分析场地效应和上/下盘效应对竖向地震动的影响;分析竖向加速度反应谱(a PS,阻尼比0.05)的特征,并提出一个简单的竖向设计反应谱;利用竖向和水平向地震动衰减关系直接得到地震动竖向与水平向比(V/H)的关系,分析不同距离不同周期V/H的特征.结果表明:竖向地震动受场地效应和上/下盘效应的影响;竖向反应谱和水平向反应谱在卓越周期、特征周期、峰值的震荡周期跨度及下降段的衰减速率都存在较大的差异;V/H离散性较大,且在不同周期不同距离表现出完全不同的特征,而V/H的场地效应和上/下盘效应是由竖向和水平向地震动的场地效应和上/下盘效应的强弱不同造成的;加速度反应谱的V/H呈现出两个极值的“马鞍型”,但在不同距离具有不同的特征,近场最大极值出现在高频段(t<0.1 s),而远场最大极值出现在低频段(t>1 s).中国未来一段时间竖向地震动的研究到应用的过程一方面可以不断完善竖向设计反应谱,另一方面可以考虑利用V/H的关系求关键点的强度.To study the vertical ground motion characteristics of Wenchuan earthquake,a vertical ground motion attenuation relationship was fitted.First,the site effect and hanging/foot wall effect on the vertical ground motion were investigated,and the characteristics of vertical pseudo-spectral acceleration(a PS,damping ratio 0.05)were analyzed.Then,a simple vertical design response spectrum was proposed.The vertical-to-horizontal ratios(V/H)relationship was obtained by using vertical and horizontal ground motion attenuation formulas,and the characteristics of V/H were analyzed at different distances in different periods.Results showed that the vertical ground motion was affected by the site conditions and the hanging/foot wall.There were many differences between the vertical and the horizontal response spectra,including the excellent period,the characteristic period,the period span of oscillation of peak response spectrum,and the attenuation rate of the falling phase.V/H had great discreteness,which showed completely different characteristics with the variation of distances in different periods,whereas the site effect and the hanging/foot wall effect on V/H were caused by the difference between those on vertical and horizontal ground motions.The V/H of acceleration response spectrum exhibited a“saddle type”,while it had different characteristics at different distances that the maximum value appeared in high frequency band(t<0.1 s)for near field and in low frequency band(t>1 s)for far field.Considering the process from research to application,the investigation of vertical ground motion in China in the future,on one hand,shall continuously improve the vertical design response spectrum,and on the other hand,shall consider estimating the key value of response spectrum by using the relationship of V/H.

关 键 词：汶川地震 竖向地震动 衰减关系 反应谱 地震动竖向与水平向比 

分 类 号：P315.9[天文地球—地震学]