【作者】 尹越；

【导师】 周宝峰；

【作者基本信息】 中国地震局工程力学研究所 ， 防灾减灾工程及防护工程， 2025， 硕士

【摘要】 大地震通常伴随复杂的地面运动特征,如破裂方向性效应、滑冲效应和上下盘效应等。其中,断层滑冲效应所产生的长周期速度脉冲,以及地面较大的永久位移和瞬态位移,对地下输油气管道、隧道、跨断层大桥及其他生命线系统等线状工程构成显著不利影响。因此,研究永久位移和瞬态位移地震动对跨断层结构物的抗震设防和安全性评估具有重要意义。然而,近断层地震动的观测记录相对稀少,跨断层记录尤为不足,这为跨断层永久位移型地震动的研究带来显著挑战。基于地球物理方法的地震动模拟在研究跨断层永久位移产生及影响机制方面具有重要作用。因此,本文围绕跨断层永久位移型地震动的特征及分布规律,开展了经典大震近断层永久位移型地震动模拟、基于设定地震的永久位移模拟以及永久位移的影响因素研究和预测模型构建。主要研究内容及结论如下:(1)基于离散波数法的大震近断层永久位移模拟及跨断层特征分析:采用离散波数法与震源反演数据,模拟了中国集集地震和汶川地震近断层永久位移型地震动,利用实际观测记录验证模拟方法的准确性。进一步开展了近断层永久位移场的模拟,并分析了永久位移的跨断层特征。模拟方法有效地再现了断层两侧永久位移型地震动,模拟与观测记录的速度和位移波形均吻合较好;同时,模拟结果与地理测量的同震位移也表现出较好的一致性。断层两侧永久位移特征与震源机制高度吻合,且位移大小与断层滑动量的空间分布紧密相关。上盘效应明显,永久位移随距离增加衰减较快。模拟方法能够有效反映永久位移的近断层和跨断层特征。(2)基于设定走滑地震的跨断层永久位移影响因素研究:通过断层倾角、滑动角、尺寸及上界面埋深等参数的组合,模拟了 375个设定走滑地震的永久位移,系统分析了断层参数变化对断层两侧三分量永久位移随距离衰减规律的影响,基于模拟数据,采用多项式回归方法初步构建了跨断层永久位移预测模型。结果表明,在走滑地震中,断层参数对不同方向的永久位移影响规律存在显著差异,同时对断层两侧永久位移影响亦不相同;且不同方向的永久位移对断层参数的敏感性受距离的影响较大,所构建的永久位移模型能实现较好的预测性能。(3)基于设定逆冲地震的跨断层永久位移影响因素研究:采用与走滑地震类似的设定方法,模拟了 960个设定逆冲地震的永久位移,研究了断层参数对逆冲地震跨断层永久位移的影响机制并构建预测方程。结果表明,断层参数对逆冲地震断层两侧永久位移的影响规律与走滑地震存在显著差异。不同参数对断层上下盘永久位移的影响有明显区别,构建的永久位移模型能良好的实现逆冲地震跨断层永久位移的预测。更多还原

【Abstract】 Strong earthquakes are typically accompanied by complex ground motion characteristics,such as rupture directivity effects,fling-step effects,and hangingwall/footwall effects.Among these,the long-period velocity pulses generated by fault fling-step effects,along with the large permanent and transient displacements of the ground,pose significant adverse impacts on linear engineering structures such as underground oil and gas pipelines,tunnels,cross-fault bridges,and other lifeline systems.Therefore,studying the effects of permanent and transient displacement ground motions on the seismic fortification and safety assessment of cross-fault structures is of great importance.Due to the relative scarcity of near-fault ground motion records,particularly the insufficiency of cross-fault records,research on cross-fault permanent displacement ground motions faces considerable challenges.Ground motion simulations based on geophysical methods play a crucial role in investigating the generation mechanisms and impact mechanisms of cross-fault permanent displacements.Consequently,this paper focuses on the characteristics and distribution patterns of cross-fault permanent displacement ground motions,conducting research on near-fault large-earthquake permanent displacement simulations,scenario earthquake-based permanent displacement simulations,and the influence mechanisms of permanent displacements.The main research contents and conclusions are as follows:(1)Simulation of Near-Fault Permanent Displacements in Major Earthquakes Using the Discrete Wavenumber Method and Analysis of Cross-Fault Characteristics:This study employed the discrete wavenumber method combined with source inversion data to simulate near-fault permanent displacement ground motions for the Chi-Chi(Taiwan)and Wenchuan(Sichuan)earthquakes in China.The accuracy of the simulation method was validated using actual observational records.Furthermore,spatial distribution fields of near-fault permanent displacements were simulated,and cross-fault characteristics of permanent displacements were analyzed.The simulation method effectively reproduced permanent displacement ground motions on both sides of the fault,with simulated velocity and displacement waveforms showing good agreement with observational records.Additionally,simulation results demonstrated strong consistency with co-seismic displacements from geodetic measurements.The characteristics of permanent displacements across the fault align closely with the seismic source mechanism,while displacement magnitudes exhibit a strong correlation with the spatial distribution of fault slip.The hanging-wall effect is pronounced,with permanent displacements decaying rapidly with increasing distance.The simulation method effectively captures both nearfault and cross-fault characteristics of permanent displacements.(2)Research on Influencing Factors of Cross-Fault Permanent Displacements Based on Scenario Strike-Slip Earthquakes:By combining parameters such as fault dip angle,rake angle,size,and upper interface burial depth,permanent displacements for 375 scenario strike-slip earthquakes were simulated.The influence of fault parameter variations on the distance-decay patterns of three-component permanent displacements on both sides of the fault was systematically analyzed.Based on the simulation data,a polynomial regression method was used to preliminarily construct a predictive model for cross-fault permanent displacements.Results indicate that in strike-slip earthquakes,fault parameters significantly and differentially affect the mechanisms of permanent displacements in different directions and on different sides of the fault.The sensitivity of permanent displacements in different directions to fault parameters is highly distancedependent.The constructed permanent displacement model achieves good predictive performance.(3)Research on Influencing Factors of Cross-Fault Permanent Displacements Based on Scenario Thrust Earthquakes:Using a setting method similar to that for strike-slip earthquakes,permanent displacements for 960 scenario thrust earthquakes were simulated.The influence mechanisms of fault parameters on cross-fault permanent displacements in thrust earthquakes were investigated,and predictive equations were constructed.Results show that the mechanisms by which fault parameters affect permanent displacements on both sides of thrust earthquakes differ significantly from those in strike-slip earthquakes.Different parameters distinctly influence permanent displacements on the hanging wall and footwall.The constructed permanent displacement model effectively predicts cross-fault permanent displacements for thrust earthquakes.更多还原