河谷地形对土层地震反应的影响

Effect of valley topography on the seismic responses of soil sites

为了分析河谷对土层地震反应的影响,采用二维有限元法,对跨度500m的某河谷地形的土层进行地震反应分析.为研究地震波传播过程对土层地震反应的影响,分析比较了一致地震输入和行波地震输入作用下土层线性和等效线性化地震反应的差异.同时将有限元计算结果与层状土层的一维波动分析结果相比较,讨论河谷地形对土层地震反应的影响.数值计算的结果表明:在水平地震输入作用下,由于河谷的存在,在河谷附近将会激起较大的竖向运动;与一致地震输入相比,在行波地震输入作用下,土层表面水平加速度反应减小,竖向加速度反应增大.

In order to analyze the effects of valley topography on the seismic responses of soil sites, the linear and equivalent-linear seismic responses of a valley with a span length of 500 m were calculated by applying the direct finite element method, respectively. As the span of the valley is large, the discrepancy of seismic responses of the soil sites was compared under uniform excitation and traveling wave excitation. At the same time, based on the wave propagation theory, the seismic responses of layered soil were evaluated for discussing the valley topography effect. The results show that the valley topography effect will lead to considerable vertical motion. Comparing with uniform excitation, the horizontal acceleration response is decreased and the vertical acceleration response is increased when under the excitation of traveling waves.