【摘要】 复杂的震源破裂过程会导致近断层区域的地震动表现出复杂特性(上盘效应、方向性效应、脉冲效应等)，且国内外相关规范均规定，对于重大工程，需考虑所在场地的具体地震环境与目标危险性水平，且采用与该场地相关的地震动.本文综合考虑概率性和确定性两种方法的优点，提出一套概率-确定性地震动预测新方法.首先在地震活动性及危险性计算上采用基于中国概率地震危险性分析(CPSHA)计算与分解的概率方法，得到具有概率意义的设定地震.然后在断层发震机制、地震影响场上采用考虑混合震源破裂模型的宽频地震动混合模拟方法.采用谱元法(SEM)进行低频(≤1 Hz)地震动模拟，引入可考虑高频随机散射的GP15.4运动学混合震源模型以及沉积层非线性分析模块，将得到的确定性结果与修正的三分量随机有限断层方法模拟的高频地震动(>1 Hz)相结合.以天津宝坻区某重要建筑(自振周期1 s)罕遇地震为例，阐述并验证了本方法用于近断层重要建筑结构抗震设防的合理性与先进性.结果表明，本方法相比传统基于一致危险谱的人工合成地震动方法更为合理，且具有显著的近断层效应，针对近断层重大工程得出其具有概率意义且与场地相关的地震动与相关规范要求契合.本研究对城市规划、近断层地震灾害模拟与地震风险评估、降低活断层区域重要工程地震风险具有重要的价值.更多还原

【Abstract】 The complex rupture process of a seismic source can result in intricate ground motion characteristics in near-fault regions(hanging wall effects, directivity effects, and pulse effects). Both domestic and international regulations stipulate that for major engineering projects, it is essential to consider the specific seismic environment and the target hazard level of the site, and to adopt site-specific ground motions. In light of this, this study proposes a novel probabilistic-deterministic hybrid seismic ground motion prediction method that combines the advantages of both probabilistic and deterministic approaches. The proposed method first employs a decomposed probabilistic approach based on CPSHA(Chinese probabilistic seismic hazard analysis) to calculate seismic activity and hazard, yielding a scenario earthquake with probabilistic significance.Subsequently, a hybrid broadband ground motion simulation method considering a hybrid source rupture model is employed on the fault rupture mechanism and site-specific seismic impact field. Low-frequency(≤1 Hz)ground motions are simulated using the spectral element method(SEM), while high-frequency(>1 Hz) ground motions are simulated using a modified three-component stochastic finite-fault method, and then combined with the deterministic low-frequency results. In the high-frequency simulation, a GP15.4 hybrid kinematic source model is adopted to account for high-frequency random scattering, together with a nonlinear sedimentary layer analysis module. As a case study, the method is applied to a critical structure in Baodi District, Tianjin, with a natural period of 1s, under a rare seismic event. This study illustrates and validates the rationality and advancement of the proposed method for seismic design of important buildings and structures in near-fault regions. The results demonstrate that this new method is more reasonable compared to traditional artificial ground motion synthesis methods based on uniform hazard spectra, and it effectively exhibits significant near-fault effects. The site-specific probabilistic ground motion of major projects near faults is in accordance with the code requirements. The study has significant value for urban planning, near-fault seismic disaster simulation,seismic risk assessment, and reducing seismic risks for critical engineering projects in active fault zones.更多还原