基于快速边界元方法的倾滑断层近场效应和盆地聚焦效应耦合作用研究  

Coupling effect of dip-slip fault near-field effect and basin focusing effect based on fast boundary element method

作　　者：刘中宪 周涛[1] 黄振恩 黄磊 章博峰 LIU Zhongxian;ZHOU Tao;HUANG Zhen'en;HUANG Lei;ZHANG Bofeng(School of Civil Engineering,Tianjin Chengjian University,300384 Tianjin,China;Tianjin Key Laboratory of Soft Soil Properties and Engineering Environment,300384 Tianjin,China;School of Civil Engineering,Tianjin University,300350 Tianjin,China)

机构地区：[1]天津城建大学土木工程学院,天津300384 [2]天津市软土特性与工程环境重点实验室,天津300384 [3]天津大学建筑工程学院,天津300350

出　　处：《应用力学学报》2024年第4期896-906,共11页Chinese Journal of Applied Mechanics

基　　金：天津市重大科技专项资助项目(No.19PTZWHZ00080);天津市自然科学基金重点资助项目(No.18JCZDJC39200);天津市杰出青年基金资助项目(No.19JCJQJC62900)。

摘　　要：基于快速边界元方法和三维运动学有限断层模型,对倾滑断层作用下复杂场地地震动进行求解。以三维近断层沉积盆地为例,采用频域内动力格林函数求解散射场的地震动,以频域内地震波的相位变化反映发震断层在时域内的动态破裂过程,突破了确定性震源难以模拟高频地震波散射的瓶颈,通过设计快速边界元方法频域-时域自适应逆变换程序得到时域内地震响应,在频域和时域内皆实现了基于确定性运动学有限震源模型的地震动快速边界元法模拟,量化分析了倾滑断层动态破裂下近场沉积盆地地震动的放大效应,揭示了地震的近断层效应与盆地效应的耦合机制。结果表明:近断层效应和盆地聚焦效应存在明显的耦合作用,显著影响了盆地区域地震动的空间分布,盆地中心点的地震动相较于断层附近输入地震动放大了3.97倍;永久位移随断层距离的增加而衰减;在沉积盆地区域内,地震动持时显著延长,软土沉积对外部输入的速度脉冲有放大作用,出现幅值较大的长周期速度大脉冲;沉积盆地会显著增大近断层强震集中性的分布范围。Based on the fast boundary element method and three-dimensional kinematic finite fault model,the ground motion of a complex site under the action of dip-slip fault is solved.Taking a three-dimensional near fault sedimentary basin as an example,the dynamic Green's function in the frequency domain is used to calculate the ground motion of the disbanded radiation field,and the phase change of the seismic wave in the frequency domain reflects the dynamic fracture process of the seism genic fault in the time domain,which breaks through the bottleneck that deterministic sources are challenging to simulate high-frequency seismic wave scattering.The seismic response in the time domain is obtained by designing the frequency domain and the adaptive inverse transform program of the fast boundary element method.The fast boundary element method simulation of ground motion based on a deterministic kinematic finite source model is realized in both the frequency domain and time domain.The amplification effect of near field sedimentary basin ground motion under the dynamic fracture of dip-slip fault is analyzed quantitatively,and the coupling mechanism of near-fault effect and basin effect of an earthquake is revealed.The results show that there is an apparent coupling between the near-fault effect and basin focusing effect,which significantly affects the spatial distribution of ground motion in the basin area.The ground motion at the center of the basin is 3.97 times larger than the input ground motion near the fault.The permanent displacement decreases with the increase of fault distance.In the area of sedimentary basin,the duration of seismic motion is significantly prolonged,and the soft soil deposit amplifies the external input velocity pulse,resulting in large amplitude long-period velocity pulse;Sedimentary basins will dramatically increase the distribution range of near-fault strong earthquakes.This paper develops an efficient and accurate ground motion simulation method for near near-fault complex sites.The research conc

关 键 词：快速边界元方法 倾滑断层 沉积盆地 近断层效应 场地效应 

分 类 号：TU311.4[建筑科学—结构工程]