强透水性砂层大直径深长桩塌孔处理技术

Collapsed-bore Treatment Technology of Large Diameter and Deep Long Pile in Highly Permeable Sand Layer

基于渭河公轨合建特大桥桩基施工在钻进、钢筋笼下放过程中或完毕时塌孔等问题的应对处理技术,对所处强透水性砂层地质条件下大直径深长桩塌孔进行了原因分析、处理方案优选与实施。对于塌孔内无钢筋笼的桩位采用回填质量比为1∶10的水泥黏土混合物静置半月以上,重新进行钻孔施工;塌孔内仍有钢筋笼的桩位采用小口径钻头钻进并进行洗孔,拔笼后再成桩;钢筋笼确难拔出的采用冲击钻重新成孔。

Based on the countermeasures and treatment technologies for the collapsed-bore of pile foundation engineering of Weihe highway rail joint super major bridge during drilling,reinforcement cage lowering or completion,the causes analysis,treatment scheme optimization and implementation are carried out for the collapsed-bore of large-diameter deep and long piles in the geological conditions of strong permeable sand layer.For the pile position without reinforcement cage in the collapsed-bore,backfill cement clay mixture with mass ratio of 1:10 and leave it for more than half a month,and then carry out the drilling construction again;For the pile position with reinforcement cage in the collapsed-bore,use a smaller-diameter drill bit to drill and flush the drill hole,and then drill after pulling out the cage;If it is really difficult to pull out the reinforcement cage,the impact drill should be used to form a bore.