绿叶电站混凝土防渗墙施工中,遇花岗岩孤石、漂石(直径≥80cm、含量超过50%)及淤泥含量较大、稳定性差的粉砂层(孔深20～29m左右),槽孔易坍塌。为解决上部槽孔易塌事故,对于地下水位线以上的槽孔,采取人工超前支护成槽的方法。成槽施工方案由原来的冲击钻常规成槽改为人工开挖超前支护、冲击钻复合成槽法进行施工。 In the construction of concrete cutoff wall of Lvye Hydropower Station, when granite boulders, boulders (diameter≥80cm, content over 50%) and silt layers with large silt content and poor stability (hole depth 20 ~ 29m) Collapse. In order to solve the accidental collapse of the upper slot, a method of artificial advance support into a slot is adopted for the slot above the groundwater level line. Slotting construction program from the original impact drill into the conventional trench into artificial excavation ahead of support, the impact drill complex into the trench method of construction.