控制性结构面对地下洞室围岩稳定性的影响

Research on the impact of control discontinuities on underground caverns

控制性结构面的展布和工程特性往往决定了地下洞室的布置和工程结构形式。以糯扎渡的主厂房为原型,通过地质条件和岩土结构特征的分析,采用Flac3D数值模拟方法,研究Ⅰ级结构面对洞室群布置的控制作用和Ⅰ-2类结构面对围岩应力、变形的影响。结果表明:Ⅰ级控制性断层与洞室最近边墙(端墙)的距离小于80 m以后,洞室围岩的应力急剧增加;在距离小于60 m后其变形也急剧增加,对围岩的稳定不利。和洞室轴线小角度相交的缓倾角结构面对围岩应力的影响较大,中等倾角的结构面对围岩的变形影响较大。

The arrangement and structural form of underground caverns are determined by the distribution and engineering characteristics of control discontinuities. Taking the underground caverns of the Nuozhadu hydroelectric station in Yunnan as an example, this paper studies the impact of control discontinuities on underground caverns. Based on the analysis of geological conditions and rock mass structures. The paper also studies the control of Grade Ⅰ discontinuities over caverns layout and the impact of Grade Ⅰ-2 discontinuities on the stress and deformation of wall rocks by 3D-FLAC. The study result indicates that when the distance between Grade I fault and the nearest side wall is less than 80 m, the stress in wall rocks increases rapidly, and the deformation quantity also increases when the distance is less than 60 m and that the stress in wall rocks is affected by low-angle faults whose strike lines intersect with cavern axial line by a small angle, and the deformation of wall rocks is affected by the medium dip angle discontinuities.