构造应力与导流洞围岩的破坏分析

Analysis on textural stress and rock failure of diversion tunnels

构造应力对围岩的稳定具有重要影响。根据地应力的实测资料,考虑岩体自重和构造应力的作用,采用有限元法,结合多元回归法确定出构造应力的大小和方向。根据俞茂宏双剪强度理论把围岩的破坏分为广义拉伸破坏、广义压缩破坏和广义剪切破坏。结合一个水电站导流洞工程,分析了构造应力对导流洞围岩的应力分布、破坏特征和破坏过程的影响。计算结果表明:考虑构造应力时应力集中主要发生在拱顶和墙角等部位,边墙的应力集中不明显,破坏过程首先是边墙底角和拱顶的破坏,然后底部发生破坏,除此之外在距导流洞较远的部分单元也发生了破坏;不考虑构造应力时应力集中主要发生在边墙和墙角等部位,破坏过程首先也是边墙底角的破坏,然后是边墙中部和顶拱相继发生破坏,破坏单元主要集中于导流洞的周边。根据工程观测实际情况,可知考虑构造应力时破坏顺序基本反映了导流洞破坏的过程。

The textural stress has great effect on the stability of rock. According to the measured geo-stress data, through FEM and combined with the linear multivariate regression method, the geo-stress field was conducted. Based on Yu Maohong＇s generalized twin-shear strength theory, the failure type was classified into the generalized tension, the generalized compression the and generalized shear. Using these methods, a diversion tunnel of a large-scale hydropower station was analyzed to study the stress distribution, the peculiarity and process of failure. It was shown that the stress concentration was located at the bottom of the wall and the arch top, the stress in the wall was little and the failure happened at the bottom of the wall and the arch top, then the bottom board and some areas far from the tunnel. Under the condition without considering textural stress, the stress concentration area located in the wall and the failure happened at the bottom of the wall, then in the middle of the wall and at the arch top, the failure elements were concentrat around the tunnel. Based on the deformation observation, the results considering textural stress could reflect the real failure process of tunnels.