软土地层45m超深基坑工程设计与实践

Design and Practice of a 45m Extreme-Deep Excavation in Soft Soil Area

某科学装置项目5号井基坑最大深度达45.45 m,是目前上海地区最深的非圆形基坑。该项目实施遇到并克服了诸多挑战和新技术难题,取得一些技术创新:为控制软土超深基坑渗漏引发安全风险而采用了深墙浅帷幕相结合的双帷幕设计方案;首次在基坑中成功应用当时国内及国际最深、入土深度69 m的TRD隔水帷幕;首次开展并完成入土深度达86 m及厚度1.10 m的TRD隔水帷幕的非原位现场试成墙试验。本文结合已成功实施完成的5号井超深基坑,介绍上海软土地区45 m级超深基坑的设计与实践,重点介绍了超深基坑面临的技术问题及总体设计方案、超深地下连续墙设计、超深TRD隔水帷幕设计及非原位试成墙试验、多层承压水的降水设计与地下水控制效果,以及工程实施效果。本次设计实施可为类似工程设计与施工提供借鉴。

The maximum depth of the excavation in No.5 well of a scientific device project is 45.45 m,which is currently the deepest non-circular excavation project in Shanghai.The implementation of the project encountered many challenges and new technical problems,and relevant technological breakthroughs are achieved.Such as,the double-layer curtain design scheme combining deep wall and shallow curtain was adopted to control the safety risk caused by the leakage of the ultra-deep excavation in soft soil.The world's deepest TRD water-proof curtain with a depth of 69m was first successfully applied in the excavation project.And the ex-situ field trial wall test of TRD cement-soil mixing walls with a depth of 86m and a thickness of 1.10 m was carried out and completed for the first time.Based on the successfully implemented of No.5 well project,the design and practice of the 45m-level extreme-deep excavation in Shanghai soft soil area was introduced.Including the overall design scheme,ultra-deep diaphragm wall design,ultra-deep TRD waterproof curtain design and ex-situ wall test,precipitation design and groundwater control effect of multiple aquifers,and project implementation effect.The successful design and implementation of this project can provide reference for the similar projects.