马普托大桥南锚碇深基坑降水设计与施工

摘要

Mozambique Maputo bridge south anchor foundation adopts underground water retaining wall curtain structure with 50m O.D.,1.2 m wall thickness,56m depth,the excavation depth of foundation pit is 36.3 m.At the excavation depth of 27 m,a foundation surge accident occurred,which stopped excavation of foundation pit.This paper analyzed the cause of the foundation pit surge and the water retaining effect of the underground continuous wall,suggested the solution to use outside pit dewatering method to control the water head of the outer confined water below excavation elevation.The hydrological parameters of the site were obtained via water pumping test for deep foundation pit dewatering design,and the author introduced construction process of relief wells and the situation of dewatering stages.The dewatering treatment for deep foundation pit in south anchor of Maputo Bridge was quite successful,the project was completed smoothly and the relevant construction method and design scheme may be used as reference for similar projects.%莫桑比克马普托大桥南锚碇基础采用外径50 m、壁厚1.2 m、深度56 m地下连续墙止水帷幕结构,基坑开挖深度36.3 m.在基坑开挖至27 m深时,出现1处基底突涌事故,导致基坑无法正常开挖施工.分析基坑突涌的形成原因及地下连续墙的封水效果,提出采取坑外降水方式将基坑外部承压水水头控制在开挖面以下的处治方案.通过抽水试验获取场地的水文地质参数,进行深基坑降水设计,并介绍减压井施工工艺及分阶段实施基坑降水情况.马普托大桥南锚碇深基坑降水处治取得了较好的施工效果,保证了工程的顺利完成,相关施工方法和设计方案可为类似工程提供参考.