地下厂房围岩变形特征分析

ANALYSIS OF SURROUNDING ROCK DEFORMATION CHARACTERISTICS IN UNDERGROUND POWERHOUSE

作为一种非连续介质,岩体的变形行为与连续介质存在较大差异。以施工期变形监测资料为基础,结合地质和施工资料,对地下厂房的围岩变形特征及其机制进行分析。围岩变形的空间分布受结构面控制作用明显,不论在水平方向、垂直方向,还是在钻孔深度方向,由于结构面的存在变形均可能出现分异现象;邻近洞室开挖对围岩变形的影响较为复杂,距离越近影响越大的一般性规律不一定成立;围岩的变形主要由控制性结构面的"张开位移"构成,"张开位移"占全部变形的84%～92%。围岩的上述变形特征揭示了基于连续介质力学的数值方法的局限性,因此加强离散类数值方法(DDA等)在岩体宏观变形模拟方面的应用研究是一个值得深入探索的课题。

As a discontinuous medium, the deformation behaviour of rockmasses is quite different from that depicted by continuous media. Based on the monitored deformation date during excavation, the deformation characteristics and mechanism are analyzed for an underground powerhouse considering its geological data and excavation process. The spatial distribution of rockmass deformation is greatly controlled by geological structural planes. Whether in horizontal direction, vertical direction or along the monitoring borehole depth, the deformation difference may exist if a structural plane is encountered; the influence of the adjacent excavations on rockmass deformation is complex, and the general rule that “the nearer the distance is, the greater the influence is” may not exist; rockmass deformation is mainly composed of the “opening displacement” of major structural planes, which constitutes 84% - 93% of the monitored deformation. The characteristics mentioned above suggest the limitation of numerical methods based on mechanics of continuous media for modeling the deformation of rockmass. Therefore, application of discontinuous numerical methods such as DDA is a subject being worthy of further investigation.