φ3.8m超大直径深孔钻孔桩桩端压浆施工

Construction of Pile Base Grouting for φ3.8 m Very Large Diameter and Deep Hole Bored Piles

针对钻孔灌注桩桩端沉渣及持力层扰动问题,提出桩端压浆的解决方法。桩端压浆可减少沉渣厚度、加固桩端持力层,改善桩土界面特性,增加桩周法向应力,增强桩侧阻力的强化效应,对桩端施加预应力。通过桩端压浆提高桩基承载力的机理分析,以嘉绍跨江大桥φ3.8 m钻孔灌注桩为例,从压浆准备、压浆管布置、分循环压浆方面总结该桥桩端压浆施工方法,经检测桩底压浆质量满足规范要求。

In the light of the problem of the sediment slag and bearing layer disturbance at bases of bored piles,a solution of pile base grouting is put forward.The pile base grouting can reduce the thickness of the sediment slag,reinforce the bearing layers,improve the boundary characteristics of the piles and soil and increase the normal stress around the piles,which will in turn increase the reinforcing effect of the pile side resistance and also apply prestress to the pile bases.By way of example of the 3.8 m bored piles of the Jiashao Bridge and the analysis of improvement mechanism of the bored pile bearing capacity by the pile base grouting,the construction method for the pile base grouting for the bridge is summarized herewith from aspects of the grouting preparation,grouting pipe arrangement and circulation grouting and it is proved from the inspection and testing that the quality of the grouting can meet the requirements in the relevant technical specification.