复杂地形条件下地震波的传播研究

利用显式有限元结合透射人工边界,研究了典型山谷地形桥址对地震波传播的影响,探讨了不同入射角度、入射方向及山谷跨度对地震动地形效应的影响规律。结果表明:坡底各位置的地震动的反应相差不大,而坡顶及坡顶后一定范围内的地震动存在不同程度的放大;地震波垂直入射时引起的地表放大效应最大,山谷左右两侧地表放大效应相对相差不大;在计算桥梁结构的地震反应时可以仅考虑地震波垂直入射的情况,其结果是偏安全的;地形放大效应存在明显的方向性;山谷的放大作用和山间跨度密切相关。

Seismic wave propagation in complex topography

Seismic wave propagation in a typical mountain-valley bridge site was studied based on the explicit finite element method with artificial transmitting boundary.The topographic effects of the incident degrees,the incident directions and the span of the mountain-valley were also discussed.It was shown that the amplification effects at the bottom of slopes did not change obviously.However,the effects near the top of slope were magnified to some extent.The absolute amplification factors were the largest under the condition of normal incidence,and the difference of the relative amplification factors at the left and right sides was not obvious.The normal incidence condition could be considered and the results were safe.Meanwhile,there was obvious directivity of topographic effects.The amplification effects were related to the span of mountain-valley.