潜孔锤钻机跟管钻进在隧洞管棚施工中的应用

Application of DTH Drilling with Casing in Pipeshed Construction in Tunneling

某引水隧洞出口段向上游方向开挖至790 m时,发现掌子面及右侧边墙及洞顶出现塌方现象,掌子面顶部可见溶蚀带,隧洞开挖顶部,溶洞洞口有风。溶蚀带主要充填物以块石为主,夹黄泥,初期渗漏浑水,一段时间后转变为清水。掌子面岩体受岩溶影响,岩体破碎,经判断,属稳定性差的Ⅴ类围岩,围岩稳定性极差-差。隧洞掘进时一旦打破平衡状态,就将引起洞顶塌方,严重危及工程施工安全。采用跟管钻进管棚施工工艺,确保了施工安全,且提高了工作效率。

The front, right side wall and crown collapsed when a tunnel was excavated at chainage of 790 m toward upstream of the tunnel outlet section. The corrosion zone was revealed in the front crown. In the crown where was excavated, air occurred at the karst cave entrance. The corrosion zone is filled with block stones mainly as well as yellow mud is mixed. At the beginning, muddy water seeps and it becomes clear later. The front rockmass, impacted by the karst, is fractured. It is defined the surrounding rock of Class V which is very weak - weak in stability. Once balance is broken while excavation is performed, the tunnel crown collapse will be triggered, which will endanger seriously the construction safety. Application of the pipeshed construction by drilling with casing secures the construction safety and improves work efficiency as well.