摘要
上海地铁18号线某地铁站主体基坑开挖深度约33m,基坑开挖过程中地下连续墙缝出现漏点,由于基坑内外承压水水头差接近30m,基坑侧壁涌水涌砂严重,通过基坑内浇筑混凝土进行反压以临时维护基坑稳定,同时采用基坑外承压水降压方案,将基坑内外水头差降至5m以下,方继续开挖。由于基坑地下连续墙外侧曾采用全方位高压喷射注浆工艺(MJS)进行墙缝止水以及大直径高压旋喷(RJP)工艺进行局部加固,基坑外侧各土层受到了不同程度的扰动,为了达到坑外降压目标,采用了深埋护筒、动水填砾、气举反循环洗井等工艺,保证了单井出水量,并最终达到预期降压效果,基坑顺利开挖至底。以上述超深基坑外侧应急减压降水工程为背景,总结了复杂条件下承压水降压深井施工技术。
The excavation depth of the main foundation excavation of one Railway Station of Shanghai Metro Line 18 is about 33 m.During the excavation,there is a leak in the joint wall.Because the water head difference inside and outside the foundation excavation is close to 30 m,the leakage is serious.The concrete was poured into the excavation to temporarily maintain the stability.At the same time,the pressure-reducing scheme is used to reduce the water head difference between inside and outside of the foundation excavation to below 5 m.Due to Metro Jet System(MJS)process for wall-slot sealing and the Rodin Jet Pile(RJP)process for partial reinforcement on the outside of the underground continuous wall of the foundation excavation,the soil layers are disturbed to varying degrees.To achieve the goal of depressurization outside the excavation,the process of deep buried casing,inject water while filling the gravel park,gas lift reverse circulation is adopted to ensure the water output of the single well,and finally achieve the expected pressure reduction effect,the foundation excavation is smoothly excavated to the bottom.Based on the above-mentioned emergency dewatering project on the outer side of the ultra-deep foundation excavation,this paper summarizes the construction process of confined aquifer pressure-reducing deep well under complex conditions.
作者
钟建文
ZHONG Jianwen(Shanghai Chang Kai Geotechnical Engineering Co.,Ltd,Shanghai 200093,China)
出处
《施工技术》
CAS
2020年第S01期113-116,共4页
Construction Technology
关键词
成井工艺
动水填砾
气举反循环洗井
construction technology of well
inject water while filling gravel park
gas lift reverse circulation
