喀斯特无充填溶洞全回转钻进灌注桩钢筋笼双套网综合成桩施工技术

Construction Technology of Full Rotary Drilling Cast-in-place Pile with Reinforcement Cage and Double Net in Karst Cavity Without Filling

在喀斯特岩溶发育区,一般地质结构比较复杂,溶洞、裂隙普遍发育,在岩溶发育区进行灌注桩施工,旋挖钻机钻头受力不均匀,易发生斜孔、卡钻、掉钻,冲击钻进需要反复回填块石、黏土进行纠偏,遇到无充填的大溶洞易发生泥浆渗漏、垮孔,严重的甚至造成地面塌陷。结合实际工程,提出喀斯特无充填溶洞全回转钻进灌注桩钢筋笼双套网综合成桩施工技术,对其原理、流程、操作要点、实施效果进行了系统阐述。实践表明,本项技术在工程应用中取得了显著成效,具有钻进效率高、成桩质量好、综合成本控制好、保证现场文明施工等优点。

In the karst area, the general geological structure is relatively complex, karst caves and fractures are widely developed. During the construction of cast-in-place pile in karst development area, the force on the bit of rotary drilling rig is uneven, and inclined hole, sticking and dropping are easy to occur. Percussive drilling requires repeated backfilling of block stone and clay for deviation correction. Besides, mud leakage and hole collapse are easy to occur in large karst caves without filling, and even cause ground collapse seriously. Based on engineering parctice, this paper proposes a construction technology of full rotary drilling cast-in-place pile with reinforcement cage and double net in karst cavity without filling, its principle, process, operation points and implementation effect of the system are described. The practice shows that this technology has achieved remarkable results in engineering application, with the advantages of high drilling efficiency, good pile quality, good comprehensive cost control and civilized construction on site.