地震荷载作用下地下洞室不利地质结构塌落机制研究

目前地下结构地震动力分析主要研究围岩响应特征，对围岩中赋存的岩体结构的动力响应规律、塌落机制还缺乏深入研究。结合大岗山水电站工程地下洞室群，基于块体理论选取3种不利地质结构组合作为地下洞室群动力分析的主要结构形式，接着运用离散元程序UDEC研究两种地震动工况作用下不同不利地质结构组合切割的地下洞室围岩动力响应、变形特征以及节理的张开、滑移特征，分析开挖面附近块体的塌落机制。研究结果表明，陡倾角结构面切割形成不利地质结构对地下洞室围岩变形破坏机制影响较大；在地震荷载作用下，陡倾不利地质结构沿节理面的滑塌具有突发性，并且塌落模式随地震强度增加可能发生变化。

Study of collapse mechanism of underground caverns with unfavorable geological structures under seismic loading

Seismic response of rock is the main topic in current dynamic analysis of underground structures,but the dynamic response and collapse mechanisms of rock structures are lack of thorough study.Based on a practical hydropower project,three kinds of unfavorable geological structures are selected in the dynamic analysis of large underground caverns by using block theory.Then ground deformation history and characteristics of open and slip joints are studied under seismic loadings by a discrete element program UDEC.Simultaneously the movement mechanisms of the cutting blocks are also analyzed.The results show that steep dip geological structures have greater impact on earthquake response of underground caverns.Under the seismic loading,adverse geological structures slip along the steep incline joint with sudden.Collapse form of adverse geological structures may change with seismic load increasing.