大口径基柱孔反循环钻进，许多情况下都是在填土层或河滩冲积层中进行。在这些地层中，一般都有粒径超过钻杆内径的大卵石、漂砾或其它杂物，这些超径卵石或杂物不能被钻井液携走，聚集孔底，影响钻进，损坏钻头与设备。我们曾在南昌某工地施工 Reverse-circulation drilling of large-diameter foundation column holes is performed in a landfill or alluvium alluvium in many cases. In these formations, there are generally large pebbles, boulder, or other debris whose diameter exceeds the internal diameter of the drill pipe. These superpath pebbles or debris cannot be carried away by the drilling fluid, accumulate at the bottom of the hole, affect drilling, and damage the drill bit. equipment. We used to construct at a construction site in Nanchang