超厚软土层小直径超长冲孔灌注桩施工技术研究和应用

摘要

淤泥和淤泥质土属于软土，其含水量高，内摩擦角小，粘聚力低，抗剪强度差，不利于冲孔灌注桩的施工。对于软土层来说，塌孔和缩径是施工过程中常见的质量问题。本文结合东方电气出海口联合基地厂房（二）工程中小直径超长冲孔灌注桩的施工，运用土力学基本原理，分析了影响孔壁稳定的各种因素，确定了泥浆的合理比重，为施工提供了技术支持。并且通过控制技术参数，选用合理桩锤，采用小冲程、大泥浆比重．合理安排施工顺序等技术措施，在超厚软土层中施工小直径超长冲孔灌注桩获得成功。%Sludge and mucky soil belong to soft soil, which have properties of high water content, small internal friction angle, low cohesion and low shear strength. These properties go against the construction of impact bored pile in soil. Hole collapse and shrinkage are two common quality problems in the construction of impact bored piles in soft soil. In this paper, the construction of overlength impact bored pile with small diameter in Dongfang Dianqi workshop project is considered. By using the principle of soil mechanics, the factors that impact the hole wall stabil- ity are analyzed; the reasonable range of gravity of mud is determined which provides the technical support for con- struction; reasonable technical measures such as controlling technical parameters, selecting reasonable driving hammer, adopting small stroke and big weight mud etc. are taken and it proves successful to construct overlength impact bored pile with small diameter through ultra deep soft soil layer.