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ISSN 2096-7780 CN 10-1665/P

基于运动学震源模型的则木河断裂带设定地震强地震动场模拟

Strong Ground Motion Simulation of Scenario Earthquakes in the Zemuhe Fault Zone Based on a Kinematic Source Model

  • 摘要: 为探究则木河断裂带强震动特征,并为跨断层黑水河特大桥的抗震设计提供合理地震动输入,采用震源-传播途径-场地条件一体化的地震动模拟技术,基于有限断层震源模型开展地震动模拟,并结合脉冲识别与反应谱特征对模拟结果进行对比分析。结果表明,模拟地震动在峰值和反应谱特征上与经验模型基本一致,较高的平行断层方向上PGA和水平方向PGV主要集中在断层上盘区域,呈现显著的上盘效应;垂直断层方向上,较高的PGV与PGD主要出现在断层的两端。脉冲识别结果显示,在震中附近及断层两端存在大量脉冲型地震动,其主要由上盘过大的残余位移引起,并在地震动长周期段引起局部显著放大。研究表明,本文采用的地震动模拟方法能够合理反映近断层地震动的方向性效应与滑冲效应,可为重大工程抗震设计提供可靠的地震动输入依据。

     

    Abstract: To explore the strong motion characteristics of the Zemuhe fault and provide reasonable ground motion input for the seismic design of the cross-fault Heishuihe Bridge, the near-field strong ground motions of the Zemuhe fault were simulated by using a finite-fault modeling approach, with the help of the deterministic physics-based simulation that can explicitly describe the fault rupture process at the source, the propagation of the resulting seismic waves, and the effects of local site conditions. Results show that the simulated motions agree well with empirical models in terms of peak value and spectra. The higher PGA in the parallel-fault direction and the PGV in the horizontal direction are mainly concentrated in the hanging wall of the fault, indicating a significant hanging-wall effect. In the perpendicular fault direction, higher PGV and PGD mainly appear at both ends of the fault. Pulse-like motions can lead to significant long-period amplification of ground motion. The method can effectively capture the directionality and fling-step effects of near-fault ground motions and provide a reliable basis for ground motion input in the seismic design of major projects.

     

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