2021年漾濞6.4级近断层宽频地震动模拟:一种改进的FK方法  

Near-fault broadband ground-motion simulation of 2021 Yangbi M6.4 earthquake:an improved FK method

作　　者：巴振宁 刘悦[1,2] 赵靖轩 张郁山[3] 梁建文 BA Zhenning;LIU Yue;ZHAO Jingxuan;ZHANG Yushan;LIANG Jianwen(Key Laboratory of Earthquake Engineering Simulation and Seismic Resilience of China Earthquake Administration(Tianjin University),Tianjin 300350,China;Key Laboratory of Coast Civil Structure Safety of Ministry of Education,Tianjin 300350,China;China Earthquake Disaster Prevention Center,Beijing 100029,China)

机构地区：[1]中国地震局地震工程综合模拟与城乡抗震韧性重点实验室(天津大学),天津300350 [2]滨海土木工程结构与安全教育部重点实验室,天津300350 [3]中国地震灾害防御中心,北京100029

出　　处：《岩土工程学报》2023年第4期709-719,共11页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(52178495);天津市自然科学基金项目(20JCYBJC01090)。

摘　　要：将基于物理的地震动模拟从现有已实现的1~2 Hz分辨率拓展到工程结构敏感的5~10 Hz更高频率,是现代地震工程近断层地震动模拟的重要发展方向。建立一种改进的频率波数域(FK)方法,结合GP14.3混合震源模型,实现了0~10 Hz的近断层地震动高效模拟。方法建立修正动力刚度矩阵法求解理论格林函数,有效解决了一维地壳速度结构传播高频地震波的问题;有限断层面上低频确定性成分及高频随机成分的合理结合,有效解决了断层破裂过程辐射出高频地震波的问题。将方法应用于2021年5月21日云南漾濞6.4级浅源破坏地震模拟,通过与8个台站(涵盖了近场、中场和远场)强震记录及相应反应谱的比较显示,模拟结果与强震记录的波形、持时、幅值均吻合良好,与反应谱在各频段上均表现良好的一致性,很好地验证了该方法及模型的适用性及模拟频率带宽的可靠性。最后,模拟了漾濞地区100 km×100 km范围内的地面运动场,给出了地面运动峰值分布和波场快照,提出了与震中距相关的PGA和PGV经验衰减公式,获得了地震动频谱特征衰减规律。结果表明:①2021年漾濞6.4级地震呈现明显近断层地震集中性效应和破裂方向性效应;②近场20 km范围内,地震动峰值衰减较快,PGA最大衰减93.1%、PGV最大衰减83.3%;③近场范围内频谱成分主要包含0~10 Hz的宽频成分,震中距超过20 km后频率成分主要集中在0~4 Hz范围内。Extending the physics-based ground-motion simulation from the existing 1~2 Hz resolution to the higher frequencyof 5~10 Hz,which is sensitive to the engineering structure,is a critical development direction of near-fault ground-motionsimulation in modern seismic engineering.An improved frequency-wavenumber domain(FK)method is established,combinedwith the GP14.3 hybrid-source model,to achieve an efficient simulation of 0~10 Hz near-fault ground motion.A revisedstiffness matrix method is established to solve the theoretical Green's function,with which the problem of propagation ofhigh-frequency seismic waves in the 1D velocity crustal structure is effectively solved.The reasonable combination oflow-frequency deterministic parts and high-frequency stochastic parts on the finite-fault plane effectively solves the problem ofhigh-frequency seismic waves radiated from the rupture process.The method is applied to the simulation of the M6.4 shallowdamage earthquake in Yangbi of Yunnan on May 21,2021.The comparison with the strong-earthquake records at eight stations(covering the near-field,mid-field,and far-field)and the response spectra shows that the simulated results are in goodagreement with the waveform,duration and amplitude of therecords,and agree with the response spectra in each frequencyband,which well verifies the applicability of the proposedmethod and model and the reliability of the simulated frequency bandwidth.Finally,the ground motions within the range of 100 km×100 km at the regional scale are simulated,and the PGAdistribution and velocity wavefield snapshots in the Yangbi area are given.The PGA and PGV empirical attenuation equationsand the spectral characteristics are proposed.The results show that:(1)The 2021 Yangbi M6.4 earthquake exhibits obviousconcentration effects and rupture directional effects.(2)The peak ground motion attenuation is faster within 20 km of the nearfield,that is,the maximum attenuation of PGA is 93.1%,and the maximum attenuation of PGV is 83.3%.(3)The frequencycomponents in the

关 键 词：宽频地震动模拟 近断层地震动模拟 频率波数域方法 混合震源模型 漾濞地震 

分 类 号：TU435[建筑科学—岩土工程]