考虑沉积河谷非线性放大效应的空间相关多点地震动模拟

SPATIAL CORRELATED MULTI-POINT GROUND MOTION SIMULATION IN SEDIMENTARY VALLEY CONSIDERING SOIL NON-LINEARITY

提出了一种考虑土体非线性特性的沉积河谷空间相关多点地震动模拟方法,该方法结合了合理的谱密度函数、相干函数以及考虑土体非线性和场地散射效应的位移幅值比。其中,场地非线性位移幅值比由有限元——间接边界元耦合的等效线性化法计算,并以V形半满河谷模型为例验证了该方法的合理性与可行性。计算结果表明:同线性模型结果相比,考虑土体非线性后,地面运动加速度时程峰值减小,反应谱卓越周期有所延长,且变化幅度与覆盖层厚度有关。覆盖层越厚,变化幅度越大,非线性效果越显著。该文研究可为河谷场地大跨度工程结构抗震设防提供重要方法和科技支撑。

A simulation method for spatial correlated multi-point ground motion in sedimentary valley considering soil nonlinear properties is proposed,which combines the reasonable spectral density function,the coherent function and the displacement amplitude ratio considering soil non-linearity and field scattering effect.Among them,the field nonlinear displacement amplitude ratio is calculated by the equivalent linearization method of coupled Finite Element-Indirect boundary element.The rationality and feasibility of the method are verified by the V-shaped semi-full valley model.The results show that,compared with the linear results,the peak value of ground motion acceleration decreases and the predominant period of response spectrum increases with the nonlinearity of the soil considered,and the magnitude of change is related to the thickness of the covering layer.The thicker the overburden,the greater the variation range,and the more significant the nonlinear effect.The research in this paper can provide important method and scientific support for seismic fortification of long-span engineering structures in valley site.