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

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。

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.