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瀑布沟水电站地下厂房洞室群包括6条引水隧洞、地下厂房、主变室、尾调室和2条尾水隧洞,布置于大渡河左岸花岗岩山体中。本文在简介洞室群布置、工程地质条件、监测设计和实施情况的基础上,着重分析了地下厂房、主变室和尾调室等三大洞室的变形量级与变形特征,评价了洞室群的稳定性。瀑布沟水电站地下厂房洞室群围岩质量整体较好,变形一般小于40 mm,但是局部受结构面影响变形较大,最大变形可达105 mm。变形较大部位一般出现在侧墙的上部,如主厂房的岩锚梁部位附近。结构面对围岩变形的控制作用显著,其上下盘的差异变形导致了施工过程中的岩锚梁开裂现象。因此,洞室群监测设计和岩锚梁结构设计均需要考虑这类局部差异变形现象。围岩变形的时效特征不显著,开挖施工结束后围岩变形与支护结构应力收敛速度较快,位移变化速率基本在1 mm/月以内,应力变化速率基本在5MPa/月以内,洞室群稳定状况良好。
The underground cavern group of Pubugou Hydropower Station consists of 6 diversion tunnels, underground powerhouse, main transformer room, tail transfer room and 2 tailrace tunnels, which are arranged in the granite mountain of the left bank of Dadu River. Based on the introduction of the layout of caverns, engineering geological conditions, monitoring design and implementation, this paper focuses on the deformation magnitude and deformation characteristics of underground powerhouse, main transformer chamber and tail transfer chamber, Group stability. The surrounding rock quality of underground caverns in Pubugou Hydropower Station is generally good, and the deformation is generally less than 40 mm. However, the deformation of the surrounding rock affected by the structural surface is large and the maximum deformation can reach 105 mm. Larger deformation generally appear in the upper part of the side wall, such as the main plant near the rock anchor beam. The structural control of surrounding rock deformation is significant. The differential deformation of the upper and lower plates leads to the cracking of rock anchor beam during construction. Therefore, the design of cavern group monitoring and the design of rock-anchor beam need to consider such phenomenon of local differential deformation. The deformation characteristics of surrounding rock are not significant. After the construction of excavation, the deformation of surrounding rock and the stress convergence of support structure are fast, the rate of displacement change is basically within 1 mm / month, the rate of stress change is within 5MPa / month, The group is in good condition.