糯扎渡水电站1~#导流隧洞三维非线性有限元开挖模拟分析

糯扎渡水电站1#导流隧洞开挖经过F3断层,开挖过程中,F3断层影响带附近的岩体力学参数直接控制着围岩的变形和应力分布.为了评判后续Ⅱ,Ⅲ层开挖围岩的稳定性,首先利用隧洞第Ⅰ层开挖的位移监测数据反演出F3断层附近围岩的岩体力学参数和初始地应力场;然后,利用反演得到的初始地应力场和岩体力学参数进行Ⅰ,Ⅱ,Ⅲ层开挖模拟分析,得到了F3断层附近围岩的应力变形情况.计算结果表明:随着开挖的不断进行,隧洞F3断层周围岩体的约束逐渐解除,围岩的应力逐渐增大,隧洞周边的位移也不断增大,并且隧洞周围应力变形在F3断层中心区域有明显的错动现象,说明F3断层对隧洞的开挖影响比较大,有必要对此区域后期变形加强观测和分析.

Three-dimensional nonlinear finite element simulation of excavation of the diversion tunnel No.1 for Nuozhadu Hydropower Station

During the excavation of the diversion tunnel No.1 for Nuozhadu Hydropower Station passing through the fault, F3 in the process of excavation, the strain and stress distribution of wall rock is controlled by the rock mass mechanical parameters around the influence zone of fault F3. Aiming to evaluating the stability of wall rock because of the excavation of layersⅡand Ⅲ; firstly, it needs back analysis of the rock mass mechanical parameters and the initial stress field of the wall rock around the fault F3 by using the displacement monitor data after the first layer excavation. Then, modeling of the first, second and third layers excavation used the rock mass mechanical parameters and the initial stress field which get through with back analysis method. The stress-strain situation of wall rock surrounds the fault F3 has got. The compute results show that the restriction of the tunnel rock mass surrounds the fault F3 is released gradually; the stress of the wall rock is increased gradually; and the displacements of the wall rock are also increased gradually with the uninterrupted excavation. And the stress-strain in the center zone of the fault F3 is unbalanced in evidence. It is shown that the excavation of the tunnel influenced by the fault F3 is obvious, monitor and analysis of later deformation in this zone need to be strengthened.