我队在某地施工中钻孔要钻透厚达几十至二百米的砂卵砾石、泥砂沉积或第三系粘土层,之后始达基岩.平均孔深350米,最深500米.施工中,钻孔都有不同程度的坍、掉、漏、涌、缩径等现象.起初,我们使用普通高粘度泥浆护壁,穿过复杂孔段后,下套管继续钻进.但不能抑制松软地层粘土的水化膨胀,泥皮厚而不 Our team drilled a hole in a construction site to drill sand, gravel, silt sediments or Tertiary clay layers that were several tens to two hundred meters thick, and then started to bedrock. The average hole depth was 350 meters and the deepest 500 meters. Construction, the drilling borehole has varying degrees of collapse, loss, leakage, Chung, Diameter reduction and other phenomena.First, we use the ordinary high viscosity mud wall, through the complex hole segment, the casing to continue drilling, but can not suppress Soft formation of clay hydration expansion, thick mud instead