考虑宽频带地震动传播过程的汶川大地震盆地介质非线性影响研究

It is the current international topics that studying on nonlinear effects of basin media in Wenchuan earthquake of considering wave propagation process of broadband ground motion. The engineering equivalent linearization method can not be applied to this study, because it can not consider the structure of the basin and soil hysteretic constitutive and other issues. In this project, soil dynamic nonlinear constitutive model under a non-symmetric load, the composite stress state, is built by soil test, soil dual parabola constitutive model of flexible hysteresis curve forms to fit the experimental damping ratio, was introduced, Newmark the "new" explicit step by step integration formula of solving triple-response in time-domain are used. Wave low-frequency ground motion of the basin basement is obtained through the numerical simulation for the overall model of simplified the shallow basin structure, earth media models and the seismic source fault rupture model. Stochastic finite fault superposition method is used for synthesizing the high-frequency ground motion of the basin basement. The fine basin structure model is built by drilling engineering, geological survey and geotechnical test, and basin medium broadband nonlinear seismic response characteristics of analog and reproduction has been realized. The impact law of basin medium nonlinear parameters to ground motion peak, the response spectrum and the duration are studied, which reveals the basin effect mechanism of the Wenchuan earthquake. The study can provide a scientific basis for major projects in disaster prevention and mitigation. Simultaneously,the study has an important guiding significance for the effect of the basin, soil dynamic constitutive, nonlinear theory, numerical analysis methods and fault kinematics, etc.

考虑宽频带地震动传播过程的汶川大地震盆地介质非线性影响研究是当今国际前沿课题，工程中传统等效线性化方法因不能考虑盆地结构、土体滞回本构等问题而不再适用。拟以土工试验构建非对称荷载、复合应力状态的土动非线性本构模型，引入灵活滞回曲线形式拟合试验阻尼比的土动双型抛物线本构模型，采用可同时求解三联反应的Newmark"新"显式时域逐步积分格式，以简化浅表盆地结构、地球介质模型和震源断层破裂模型为一整体，由波动数值模拟方法获得盆基底低频地震动；利用随机有限断层叠加合成盆基底高频地震动，以工程钻探、地质调查和土工试验构建精细的盆地结构模型，实现对盆地介质宽频带非线性地震动响应特性的模拟和再现，研究盆地介质非线性参数对地震动峰值、反应谱和持时的影响规律，揭示汶川大地震的盆地效应机理，为重大工程防灾减灾提供科学依据。该研究对于盆地效应、土动本构、非线性理论、数值分析方法、断层运动学等具有重要的指导意义。

考虑宽频带地震动传播过程的汶川大地震盆地介质非线性影响研究是当今国际前沿课题，工程中传统等效线性化方法因不能考虑盆地结构、土体滞回本构特性等问题而不再适用。本文以土工试验结果为基础，构建了非对称荷载、复合应力状态下的土体动力非线性本构模型，引入了灵活滞回曲线形式，以拟合试验阻尼比的土体动力双型抛物线本构模型，采用了可同时求解三联反应的Newmark“新”显式时域逐步积分格式和三维有限差分GMS技术，采用接力棒技术，实现了浅表盆地结构、地球介质模型和震源断层破裂模型为一整体的大体系地震波动数值模拟和再现。通过有限差分波动数值模拟方法获得了盆地基底处的低频地震动；采用经验格林函数方法叠加合成了盆地基底位置的高频地震动，以工程钻探、地质调查和土工试验构建了精细的盆地结构模型，实现了对盆地介质宽频带非线性地震动响应特性的模拟和再现，研究了盆地介质对地震动传播的影响规律，盆地结构对地震动的放大效应及其影响特点。揭示了汶川大地震的汉源地区烈度异常的一些机理，为重大工程防灾减灾提供科学依据。该项研究对于盆地效应特性、土体动力本构关系的理解、非线性体系理论、数值模拟分析方法、断层震源运动学研究等具有重要的指导意义。