岩溶地区钻孔灌注桩施工技术

Construction technology of bored cast-in-place pile in karst area

岩溶地区溶洞、硬质斜岩和破碎岩给桩基施工带来诸多技术难题,为确保桩基质量,依托贵隆高速公路项目,进行了一系列试验研究,首先借助超前钻孔,获取每根桩基详细的地质信息;其次由于溶洞规模较小,主要采取了抛填片石、黏土(水泥)挤压填充、低锤高频的处理方法;对于硬质斜岩岩层,则采用了动态调整旋挖钻的钻速,并分级扩孔处理桩径为1.8 m的大桩径桩基;采取泥浆护壁、护筒跟进的措施处理破碎岩层。通过运用上述方法,降低了施工成本,提高了施工功效,缩短了施工工期。

Karst cave, hard rock and broken rock have brought many technical problems to the pile foundation construction, in order to ensure the quality of pile foundation, relying on the Guigang-Long＇an Expressway project, we conducted a series of research experiments. Firstly, with advanced drilling, access to each root detailed geological information of pile foundation; secondly, due to the small size of the cave, the method mainly adopts the processing method of thrown stone, clay （ cement） extrusion filling, and low hammer high frequency; for hard rock strata, the dynamic adjustment screw drilling speed drilling, and grading reaming treatment of pile diameter of 1.8 m large pile diameter pile; to take the mud retaining wall, casing follow-up measures to deal with broken rock. By using the above method, the construction cost is reduced, the construction efficiency is improved, and the construction period is shortened.