青岛地区嵌岩打入桩工程质量分析

Engineering quality analysis of rock-socketed driven pile in Qingdao area

本文依托青岛某实际工程,对打桩过程中出现的桩端难以进入设计持力层的问题进行分析,并选取两根出现问题的工程桩进行静载荷试验。结果表明:Q-s曲线在最后一级荷载作用下出现陡降,初步认为是桩端岩体发生破坏所致,通过进一步分析发现造成曲线陡降的原因是由于试验过程中桩顶被压碎。结合地基土性质和施工情况,提出了变更设计持力层的解决方案。通过嵌入持力层为硬岩、泥质软岩和硬质土中打入桩的Q-s曲线,分析了岩土体强度对嵌岩打入桩变形特性的影响。

The problem that the pile end is difficult to drive into the designed stratum during the driving process is discussed of a piling project in Qingdao. Two piles with this problem are selected to carry out the static load test. The results show that the Q-s curve appears steep decline under the final load,which is preliminarily thought to be caused by the failure of the rock mass at the pile bottom,while further analysis finds that the sharp decline is caused by the crushed pile top during the test. An alternative design that changing the founding stratum is proposed considering the site geological and construction condition. Based on the static load Q-s curves of three kinds of driven piles with different bearing stratum,which are hard rock,soft rock and stiff soil,the influence of rock-soil strength on the deformation characteristics of rocksocketed driven piles is analyzed.