基于有限断层随机地震动合成的高速路网地震危险性分析

SEISMIC HAZARD ANALYSIS FOR HIGHWAY NETWORK BASED ON STOCHASTIC FINITE FAULT MODELING OF GROUND MOTIONS

  • 摘要: 针对传统概率地震危险性分析和点源模型的不足,利用表达震源-传播途径-场地条件一体化的有限断层随机地震动合成方法,对覆盖多个不同烈度区的西南地区某高速路网进行了地震动合成,利用统计方法拟合了峰值加速度和反应谱值的预测公式,进而得到路网桥梁节点的地震风险曲线,并在不同设防水准下与传统地震风险曲线进行了对比。结果表明:多遇地震水准下,基于本文方法的地震风险曲线可以提供更为保守的地震动设计参数;偶遇、罕遇和极罕遇三种水准下,基于传统方法的地震风险曲线给出的地震动设计参数则更为保守;两种方法给出的地震动参数值差异存在显著方向性,说明基于有限断层震源模型是对传统地震风险分析方法的重要补充,从发震物理机制上对路网风险分析提供了更多的科学性依据。

     

    Abstract: To improve the shortcoming of the traditional point-source based probability seismic hazard analysis (PSHA), the stochastic finite-fault modeling approach, which involves source, propagation path, and local site, is used to simulate ground motions for a given highway network that covers several intensity regions in southwest China. Based on simulated motions, the ground motion prediction equations (GMPEs) for peak ground acceleration (PGA) and pseudo spectral acceleration (PSA) are obtained by regression. The GMPEs are then applied in PSHA to obtain the seismic hazard curves for the bridges of the highway network. The obtained hazard curve is compared to the hazard curve computed based on traditional GMPEs for various hazard level. The result shows that:for a frequent earthquake, the simulation-based hazard curve provides safer ground motion parameters than the record-based hazard curve; for a basic, rare, and very rare earthquake, the ground motion parameters from record-based hazard curve are more conservative; the difference of the parameters between two hazard curves shows an obvious directivity, which indicates that, by involving finite fault model, PSHA is strengthened to represent the effect of fault mechanism.

     

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