隧道建设
隧道建設
수도건설
Tunnel Construction
2015年
11期
1194-1201
,共8页
南京纬三路长江隧道%临江超深基坑%高承压水%突涌%抗浮稳定%水下开挖%水下封底
南京緯三路長江隧道%臨江超深基坑%高承壓水%突湧%抗浮穩定%水下開挖%水下封底
남경위삼로장강수도%림강초심기갱%고승압수%돌용%항부은정%수하개알%수하봉저
Weisanlu river-crossing tunnel%ultra-deep foundation pit at riverside%high confined water%water inrush%anti-floating stability%underwater excavation%underwater bottom-sealing
临江高承压水超深基坑的成功实施必须解决坑底突涌与抗浮安全两大关键问题。通过合理的施工工序设计确保围护结构与基坑安全，并为坑内主体结构施工提供安全的施工环境。结合南京市纬三路过江隧道梅子洲风井基坑，对该类复杂基坑的重难点问题进行分析，在支护结构、开挖方法、实施方案及施工工序等方面根据工程具体特点采取相应的技术对策，确定了采用水下开挖及水下混凝土封底的技术方案，并经计算分析确定了最优施工工序。梅子洲风井的实践经验表明：对开挖深度大、承压含水层厚度及埋深均极大而导致隔水帷幕难以穿透承压含水层的基坑工程，采用水下开挖方式可有效防止基底突涌的发生，并能改善围护结构的受力与变形状态；而水下封底混凝土的设置可承受坑底巨大的承压水压力，是确保工程实施的关键措施。
臨江高承壓水超深基坑的成功實施必鬚解決坑底突湧與抗浮安全兩大關鍵問題。通過閤理的施工工序設計確保圍護結構與基坑安全，併為坑內主體結構施工提供安全的施工環境。結閤南京市緯三路過江隧道梅子洲風井基坑，對該類複雜基坑的重難點問題進行分析，在支護結構、開挖方法、實施方案及施工工序等方麵根據工程具體特點採取相應的技術對策，確定瞭採用水下開挖及水下混凝土封底的技術方案，併經計算分析確定瞭最優施工工序。梅子洲風井的實踐經驗錶明：對開挖深度大、承壓含水層厚度及埋深均極大而導緻隔水帷幕難以穿透承壓含水層的基坑工程，採用水下開挖方式可有效防止基底突湧的髮生，併能改善圍護結構的受力與變形狀態；而水下封底混凝土的設置可承受坑底巨大的承壓水壓力，是確保工程實施的關鍵措施。
림강고승압수초심기갱적성공실시필수해결갱저돌용여항부안전량대관건문제。통과합리적시공공서설계학보위호결구여기갱안전，병위갱내주체결구시공제공안전적시공배경。결합남경시위삼로과강수도매자주풍정기갱，대해류복잡기갱적중난점문제진행분석，재지호결구、개알방법、실시방안급시공공서등방면근거공정구체특점채취상응적기술대책，학정료채용수하개알급수하혼응토봉저적기술방안，병경계산분석학정료최우시공공서。매자주풍정적실천경험표명：대개알심도대、승압함수층후도급매심균겁대이도치격수유막난이천투승압함수층적기갱공정，채용수하개알방식가유효방지기저돌용적발생，병능개선위호결구적수력여변형상태；이수하봉저혼응토적설치가승수갱저거대적승압수압력，시학보공정실시적관건조시。
Water inrush and bottom floating must be avoided in the construction of ultra-deep foundation pits at riverside under high confined water.Therefore,rational construction procedure should be planned for such foundation pits so as to ensure the stability of the retaining structures and the foundation pits themselves and to provide safe conditions for the construction of the main structures in the foundation pits.In the paper,the construction of the foundation pit of Meizizhou ventilation shaft of Weisanlu river-crossing tunnel in Nanjing is studied.The challenges in the construction of the foundation pit are analyzed,technical countermeasures are taken in the aspects of retaining structure,excavation method,implementation plan and construction procedure,the technical scheme of underwater excavation and underwater bottom-sealing is adopted,and the optimum construction procedure is determined according to the calculation analysis results.Conclusions drawn are as follows:1)For ultra-deep foundation pits where the excavation depth and the confined aquifer thickness are so large that it is difficult for the waterproof curtain to penetrate the confined aquifer,the application of underwater excavation can effectively avoid water inrush and can improve the force and deformation state of the retaining structures;2)The underwater bottom-sealing concrete,which can bear the high pressure of the confined water,is the key to the successful implementation of the project.
