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巴振宁, 刘悦, 赵靖轩, 张郁山, 梁建文. 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[J]. 岩土工程学报, 2023, 45(4): 709-719. DOI: 10.11779/CJGE20211574
引用本文: 巴振宁, 刘悦, 赵靖轩, 张郁山, 梁建文. 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[J]. 岩土工程学报, 2023, 45(4): 709-719. DOI: 10.11779/CJGE20211574
BA Zhenning, LIU Yue, ZHAO Jingxuan, ZHANG Yushan, LIANG Jianwen. Near-fault broadband ground-motion simulation of 2021 Yangbi M6.4 earthquake: an improved FK method[J]. Chinese Journal of Geotechnical Engineering, 2023, 45(4): 709-719. DOI: 10.11779/CJGE20211574
Citation: BA Zhenning, LIU Yue, ZHAO Jingxuan, ZHANG Yushan, LIANG Jianwen. Near-fault broadband ground-motion simulation of 2021 Yangbi M6.4 earthquake: an improved FK method[J]. Chinese Journal of Geotechnical Engineering, 2023, 45(4): 709-719. DOI: 10.11779/CJGE20211574

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

  • 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。

     

    Abstract: Extending the physics-based ground-motion simulation from the existing 1~2 Hz resolution to the higher frequency of 5~10 Hz, which is sensitive to the engineering structure, is a critical development direction of near-fault ground-motion simulation in modern seismic engineering. An improved frequency-wavenumber domain (FK) method is established, combined with the GP14.3 hybrid-source model, to achieve an efficient simulation of 0~10 Hz near-fault ground motion. A revised stiffness matrix method is established to solve the theoretical Green's function, with which the problem of propagation of high-frequency seismic waves in the 1D velocity crustal structure is effectively solved. The reasonable combination of low-frequency deterministic parts and high-frequency stochastic parts on the finite-fault plane effectively solves the problem of high-frequency seismic waves radiated from the rupture process. The method is applied to the simulation of the M6.4 shallow damage 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 good agreement with the waveform, duration and amplitude of the records, and agree with the response spectra in each frequency band, which well verifies the applicability of the proposed method 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 PGA distribution and velocity wavefield snapshots in the Yangbi area are given. The PGA and PGV empirical attenuation equations and the spectral characteristics are proposed. The results show that: (1) The 2021 Yangbi M6.4 earthquake exhibits obvious concentration effects and rupture directional effects. (2) The peak ground motion attenuation is faster within 20 km of the near field, that is, the maximum attenuation of PGA is 93.1%, and the maximum attenuation of PGV is 83.3%. (3) The frequency components in the near-field range mainly include 0~10 Hz broadband components. When the epicenter distance exceeds 20 km, the frequency components are concentrated primarily in a range of 0~4 Hz.

     

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