小湾水电站导流隧洞F_7断层段施工技术总结

Summary on construction technology for excavating the diversion tunnel in Fault F7 section for Xiaowan Hydropower Project

小湾水电站导流隧洞工程由2条净断面为16m×19m、长度分别为861.592m和980.922m的城门洞形隧洞组成。隧洞穿越的地层Ⅴ类围岩洞段长度分别为143m和178m,特别是穿越F7断层段,隧洞开挖断面为20.5m×23.35m,围岩极其破碎。施工中综合分析支护施工强度与进度要求,合理确定分区施工技术方案,在通过控制爆破进行开挖的基础上,采用了超前锚固、系统锚固、钢支撑辅以钢纤维喷混凝土等各种支护手段,顺利穿越了F7断层。

The diversion tunnel works of Xiaowan hydropower project is composed of two horseshoe-shaped tunnels with a net cross section of 16 m×19 m each and the length of 861.592 m and 980.922 m respectively. The length of two tunnels that pass through the surrounding rocks of category-V is 143 m and 178 m respectively. The excavation cross section of the tunnel sections which cut across Fault F7 is 20.5 m×23.35 m and the surrounding rocks there are extremely fractured. According to their support construction intensity and schedule, some proper supporting measures, including advance anchorage, systematic anchorage, steel support and steel fiber reinforced shotcrete have been taken to complete the construction of the tunnels that pass through the Fault F7 fracture zone successfully by excavation on controlled blasting basis.