To analyse on the diminish,gravitation,awrybore, conduit clogging, pipe laying, steely iron to floot,peg cutting,nipping with mud etc,and put forward some control measurecs.

• 对缩径、塌孔、斜孔、导管堵塞、埋管、钢筋笼上浮、断桩、夹泥等问题进行分析,提出防治措施。