超长钻孔灌注桩深部缺陷分析处理

Analysis and Treatment of Super-long Bored Pile Deep Defect

宁波某大桥主墩基础采用φ1500mm钻孔灌注桩,桩长90m。其中一根桩施工时因导管堵塞进行了二次灌注,发生深部缺陷事故。考虑缺陷以上桩段部分不能满足设计要求,需进行深部缺陷检测和处理。由低应变动测、钻芯法等手段检测确定产生深部缺陷的部位,提出采用桩体内注浆加固的处理方案。介绍了超长钻孔灌注桩钻孔取芯、注浆等施工技术。实施结果表明,桩身强度和桩身质量均达到要求,采用桩体内注浆加固的方法处理超长钻孔灌注桩深部缺陷合理有效。

φ1500mm bored piles are adopted in some bridge in Ningbo, whose length is 90m. In construction of some bored pile, deep defect is caused because of secondary pouring owing to pouring pipe occlusion. According to the condition that pile segment over the defect can＇t meet design requirements, it is necessary to monitor and treat the deep defect. The defect position is determined by low-strain dynamic test and core drilling method, thus treatment of pouring in pile is suggested. Authors introduce construction technology of core drilling and pouring of super-long bored piles. Results show that the pile strength and quality can meet design requirement, the grouting in piles method is efficient in deep defect treatment of super-long bored piles.