冲击成孔灌注桩施工工艺及质量控制要点

Construction Technology and Quality Control Essentials of Percussively Bored Cast-in-place Pile

江苏省镇江某大型企业研发大楼滨临长江,场地地基以长江漫滩冲-淤积软土沉积为主,地基基础设计采用Φ800mm泥浆护壁成孔灌注桩,桩端持力层为坚硬、强度高的中-微风化花岗岩。在现场施工过程中,由于GPS-20型钻机出现了钻进效率明显下降的情况,为加快施工进度,换用CZ-6D型冲击钻机。根据该项工程要求,介绍了CZ-6D型冲击钻机在定位放线、桩机就位、冲击成孔和清孔等冲击成孔施工过程中所采取的措施,并对其质量控制要点进行了重点说明。结果发现,采用冲击成孔灌注桩,大大提高了施工效率,工程质量达到了设计要求。该工程的成功经验,对同类型地质条件下的桩基工程设计及施工具有指导意义。

The research and development office building of a sizeable enterprise in Zhenjiang, Jiangsu is next to the Yangtze River; site foundation is mainly alluvial-silting soft soil deposits on the river＇ s flood plain. The foundation design is adopted of Φ800mm mud off bored cast-in-place pile, pile-end bearing stratum is hard and high-strength medium-slightly weathered granite. During the construc- tion, since the GPS-20 drill efficiency dramatically declining, to speed up construction schedule, changed the rig into CZ-6D percus- sion drill. The paper introduced measures adopted during the percussive boring process including CZ-6D drill positioning and setting out, pile machine taking place, percussive boring etc. according to project requirements; and highlighted quality controlling essentials as well. The result has shown that using the percussively bored cast-in-place pile has improved construction efficiency greatly; project quality met the designed requirements. The successful experience of the project has guiding significance in design and construction of foundation engineering with same types of geological condition.