iron cover

The paper analysis the reasons and give some suggestion such as adding an iron cover between the extend hole and haul pipe,choose optimization slop pressure.

结合工程实例,分析了非开挖水平定向钻进铺管施工中经常产生的卡管、摆管不顺等事故的原因,并提出了在扩孔头与拉管头之间加上铁罩、选择最优泥浆压力等解决方法,实践证明效果良好。