三轴搅拌桩组合高压旋喷桩入岩落底式止水帷幕施工技术

CONSTRUCTION TECHNOLOGY OF THREE AXIS MIXING PILE COMBINATION HIGH PRESSURE ROTARY JET GROUTING PILE ENTERING ROCK AND FALLING BOTTOM TYPE WATER STOP CURTAIN

某房建深基坑工程支护形式采用排桩+落底式止水帷幕,场地地质条件上部为富水深厚砂层,下部为强风化岩层,止水帷幕需穿透强风化岩0.5 m,以隔断强透水层。通过对地质情况及现有设备条件分析,采用大功率桩机先行施工三轴搅拌桩,养护后进行桩体质量抽芯验证,再针对不同缺陷程度采用高压旋喷桩分别进行补强的组合工艺施工止水帷幕。基坑开挖结果表明,该落底式止水帷幕效果良好,能有效隔断强透水层,与灌注排桩结合形成深基坑支护结构体系具有较高的经济性、适用性。

The support form of a deep foundation pit project for a certain building adopts row piles and bottom falling water stop curtain.The geological conditions of the site are that the upper part is a water-rich and thick sand layer,and the lower part is a strongly weathered rock layer.The water stop curtain needs to penetrate the strongly weathered rock by 0.5 m to isolate the strong permeable layer.By analyzing the geological conditions and existing mechanical equipment conditions,using a high-power pile driver to construct the three-axis mixing pile first,after curing,the quality of the pile body was verified by core extraction,and then using a combination process of high-pressure rotary jet grouting piles for reinforcement according to different degrees of defects to construct the waterproof curtain.The excavation results of the foundation pit indicate that the bottom type water stop curtain has a good effect,can effectively isolate the strong permeable layer,and is combined with cast-in-place piles to form a deep foundation pit support structure system with high economy and applicability.