考虑宽频带地震动传播过程的汶川大地震场地液化非线性影响研究

考虑宽频带地震动传播过程的汶川大地震场地液化非线性影响研究是当今国际前沿课题，因液化场地宽频带记录的缺失而使汶川特大地震砂土液化机理研究几乎限于停滞。拟利用我们开发的综合地球物理探测技术构建汶川震区三维结构模型。提出一种以GMS有限差分法，有机结合EGFM_UC“不确定性”经验格林函数法和EWPM解耦近场波动有限元法，研究复杂震源破裂产生宽频带地震动从震源断层、壳幔结构到浅表精细模型和砂土液化场地的地震波导模拟和预测方法。基于“土力学”模型，建立土骨架非线性本构关系对砂土层孔隙水压力的增长与消散规律的影响模型，提出一种可考虑宽频带不规则地震动下饱和砂土非线性地震响应分析方法，指出孔隙水压力的增长和消散对场地砂土液化规律的影响，提供新的场地液化判别公式。该研究对于宽频带地震动模拟方法及场地液化机理研究具有极其重要的理论意义，对于工程结构的抗震设防和工程场地的液化判别具有十分重要的应用价值。

Study on the nonlinear effects of liquefaction of Wenchuan earthquake site considering the propagation process of broadband ground motion is a frontier issue in the world. Study on liquefaction mechanism of sandy soil in Wenchuan earthquake is almost limited to stagnation due to the lack of broadband records of liquefaction site. The three-dimensional structural model of Wenchuan earthquake area will be constructed by using the integrated geophysical exploration technology developed by us. In this paper, a simulation and prediction method, which is GMS finite difference method combined with EGFM_UC "uncertainty" empirical Green's function method and EWPM decoupled near-field wave finite element method, is proposed to study wave propagation of broadband ground motion from source fault, crust-mantle structure to shallow surface fine model and sand liquefaction site caused by complex source rupture. Based on the "soil mechanics" model, the influence model of nonlinear constitutive relation of soil skeleton on the law of increase and dissipation of pore water pressure in sandy soil layer is established. A nonlinear seismic response analysis method of saturated sandy soil under broadband irregular ground motions is proposed. The influence of the increase and dissipation of pore water pressure on the law of liquefaction of sandy soil in site is pointed out, and a new discriminant formula for site liquefaction is provided. The study is of great theoretical significance for broadband seismic simulation and liquefaction mechanism research. It is also of great value for seismic fortification of engineering structures and liquefaction discrimination of Engineering sites.