以大岗山水电站大型地下洞室为例,分别构建了地下洞室体系简化模型和考虑山体地形与不利地质结构的复杂模型,利用显式有限差分方法分析了山体地形和大型地质结构面对洞室围岩地震响应的影响,研究地下洞室地震变形规律及响应特征。研究表明:山形地表的反射波主要表现为P波作用,地质结构面的反射、折射波主要表现为S波作用;山体地形对地下洞室上部迎波面的地震响应影响要大于下部,且上部围岩的位移与加速度响应均有一定程度的放大。地质结构面对于边墙部位洞周岩体的地震变形幅值有较大影响,对围岩加速度的放大效应也比较显著,但主要集中在距离结构面分布位置较近的有限范围内,并且地质结构面对不同频率成分的地震波的影响规律不同。
A simplified analysis model and complex models with consideration of the effects of topography, discontinuous geological plane were established and applied to the underground caverns of Dagangshan hydropower station under construction. The finite difference software FLAC is used for the seismic response analysis of surrounding rock mass of under ground caverns. The result shows that the mountain topography has some influences on seismic displacement and acceleration of upper surrounding rock mass, which mainly be imposed P-wave vibration loading. The effect of the weak structural plane which strengthening S-wave shear to the surrounding rock mass, is relatively remarkable on the earthquake response of caverns, and the effect zone of it is limited to vicinity of cutting surrounding rock mass. The effect regularity of the geological structural plane is different on earthquake waves with different frequency components.