管涌地质条件下深水钻孔施工

Deep Water Drilling Under Piping Geological Conditions

蒙西至华中铁路公安长江大桥4#墩是主跨南主塔墩,主墩为直径280cm钻孔桩基础,钻孔桩采用KPG-3000型气举反循环钻机成孔,工程所在地是典型的管涌地质,卵砾石层填充物少,极易漏浆,在钻卵砾层时采用了向孔内投放膨润土、锯末等方法堵漏护壁,在钻孔过程中经改进采用密齿重型刮刀钻头,有效地保证了钻孔安全、质量及工期。

The 4# pier of Gong’An Yangtze Bridge of Western Inner Mongolia to Central China Railway is the south main pylon pier. The main pier is a bored pile foundation with a diameter of 280 cm, and the bored pile is drilled by kpg-3000 air lift reverse circulation drilling machine. The project is located in a typical piping geology, with less filling materials in the gravel layer and easy leakage of slurry. When drilling the gravel layer, bentonite and sawdust were put into the hole to block leakage and protect the wall. The drilling process was also improved by adopting dense tooth heavy drag bit. All of the measures effectively ensured safety, quality and the construction schedule.