基于逆断层动力学模型的三维山体地震动谱元法模拟  

Three-dimensional ground motion spectral element method simulation based on inverse fault dynamics model

作　　者：巴振宁[1,2] 赵靖轩 吴孟桃 梁建文[1,2] 塔拉[3] BA Zhenning;ZHAO Jingxuan;WU Mengtao;LIANG Jianwen;TA La(Department of Civil Engineering,Tianjin University,Tianjin 300354,China;Key Laboratory of Coast Civil Structure Safety of the Ministry of Education,Tianjin 300350,China;The First Monitoring and Application Center CEA,Tianjin 300171,China)

机构地区：[1]天津大学土木系,天津300354 [2]滨海土木工程结构与安全教育部重点实验室,天津300350 [3]中国地震局第一监测中心,天津300171

出　　处：《地震工程与工程振动》2021年第3期32-42,共11页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金项目(51778413)。

摘　　要：逆冲断层是常见的断层错动形式,具有释放地震能量大破坏力强的特征,同时大量震害调查和强震观测表明,山体地形对地震动的显著放大效应会进一步加重震害,然而目前还鲜有针对逆冲断层作用下山体地震动模拟的研究。文中即采用谱元法,建立含动力学逆断层震源和三维山体地形的整体物理模型,研究了动力学逆断层地震作用下的三维山体动力响应。文中以高斯型山体为例,对其近断层地震动特性进行了分析,并着重探讨了三维山体地形对逆断层地震动产生的影响。研究表明:(1)动力学逆断层模型很好的契合了近断层地震动特性,在模拟中重现了近断层地震动的方向性效应、上盘效应、集中性效应和地面永久位移等基本特征;(2)山体对近断层地震动放大效果显著,对比无山体情况,山体加速度和位移峰值分别放大了1.79和1.21倍;同时加速度峰值随着山体高程的增加而增加,与山脚处加速度峰值相比,山顶和山腰处的加速度峰值分别放大了2.05和1.28倍;(3)山体地形引发的地震波散射和衍射效应不仅放大了山体和山体毗邻地表的地震动响应,同时延长了地震动在该区域内的响应时间。As a common form of fault dislocation,thrust fault has the characteristics of releasing seismic energy and strong destructive power.Meanwhile,a large number of seismic damage investigations and strong earthquake observations show that the significant amplification effect of mountain terrain on ground motion will further aggravate earthquake damage.However,there are few studies on the simulation of mountain ground motion under thrust fault.In this paper,the spectral element method is adopted to establish the overall physical model including dynamic reverse fault source and three-dimensional mountain terrain,and the three-dimensional mountain dynamic response under the action of dynamic reverse fault earthquake is studied.This paper takes the Gaussian mountain as an example,analyzes its near-fault ground motion characteristics,and emphatically discusses the influence of three-dimensional mountain terrain on the ground motion of reverse fault.The results show that:(1)the dynamic reverse fault model fits the characteristics of near-fault ground motion well,reproducing the basic characteristics of near-fault ground motion,such as directional effect,wall effect,concentration effect and permanent displacement of the ground.(2)The peak of acceleration and displacement of the mountain are 1.79 and 1.21 times larger than those without a mountain.At the same time,the peak acceleration increases with the elevation of the mountain,and the peak acceleration at the top and the middle of the mountain is 2.05 and 1.28 times larger than that at the foot of the mountain.(3)The seismic wave scattering and diffraction effect caused by mountain terrain not only magnifies the ground motion response of mountain and surrounding flat terrain,but also extends the response time of ground motion in mountain and surrounding flat terrain.

关 键 词：谱元法 动力学逆断层 地形效应 近断层地震动 地震波散射 

分 类 号：P315.9[天文地球—地震学]