泖港大桥提高桩基质量措施研究

Study on Measures to Improve Pile Foundation Quality of Maogang Bridge

泖港大桥为三跨变高度钢-混凝土混合连续梁,总长265m,采用钻孔灌注桩,桩基直径1.2m,桩长64m。为提高桩基成品质量,在规范要求合格的基础上,提出优良标准。通过对桩基质量的统计分析,明确“孔径”及“孔深”是不能达到优良标准是造成桩基优良率低的症结所在。“钻头老旧”、“钻进进度过快”、“仅靠反循环无法满足清孔要求”和“原位泥浆含砂量高”4个因素是未达优良标准的要因。采用5W1H的方法,制定了对策,采用“及时更新钻头设备”、“控制钻进速度”、“采用人工造浆”、“增加除砂机”等4个措施,通过现场实施和检查,桩基成品质量有所提高,优良率明显提升。

Maogang Bridge is a three-span Variable-height Steel-concrete Composite Continuous Beam Bridge. Its total length is 265 m. The cast-in-place pile is used for this bridge. The diameter of pile foundation is 1.2 m. The pile length is 64 m. In order to improve the quality of finished pile foundation, the excellent standard is proposed on the basis of standard requirements. According to the statistical analysis of pile foundation quality, the determination of "hole diameter and "hole depth" cannot reach the excellent standard and is the crux of the low good rate of pile foundation. Four factors of "old drill","too fast drilling speed","reverse circulation alone not able to meet the requirements of hole cleaning" and "high sand content in situ mud" are the essential factors not up to the excellent standard. The 5W1H method is adopted to formulate the countermeasures of "updating the drill equipment in time","controlling the drilling speed","adopting the artificial pulping" and "increasing the sand removing machines". The quality of finished pile foundation is improved and the good rate is obviously promoted through the filed implementation and inspection.