深厚砂层中后注浆钻孔灌注桩质量问题原因分析

Analysis on Quality Problems of Post-grouting Bored Pile in Deep Sand Stratum

依托某深厚砂层中后注浆钻孔灌注桩质量事故实例,基于现场试验数据、资料,结合现场调查,从设计、勘察及施工等方面对质量事故的原因进行了分析。分析结果表明,不合适的成孔和清孔工艺、不合理的注浆量、注浆速度、不合适的注浆器及注浆管的插入深度等是造成本次质量事故的主要原因。针对这些原因提出如在深厚砂层中后注浆钻孔灌注桩清孔时应采用反循环工艺,并采用2次注浆工艺,同时应保证合理的注浆量和校核注浆管与成孔深度的一致性等解决措施。成果可为穿越深厚砂层中后注浆钻孔灌注桩类似桩基工程的设计、施工提供借鉴。

A quality accident of post-grouting bored pile in deep sand stratum is discussed as an example.Based on field test data and field investigation,the causes of quality accident are analyzed from the aspects of design,investigation and construction.The analysis results show that the main causes of the quality accident are improper holing and hole cleaning technology,unreasonable grouting amount,grouting speed,grouting device and the insertion depth of grouting pipe.In view of these reasons,solving measures are put forward.Reverse circulation technology and twice grouting technology should be adopted when post-grouting bored pile is cleaned in deep sand stratum.At the same time,reasonable grouting amount should be ensured,and consistency between grouting pipe and hole forming depth should be checked.The research results can be used as reference in the design and construction of similar pile foundation engineering of post-grouting bored pile in deep sand stratum.