公安长江公铁两用特大桥4号墩钢围堰施工技术

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1、桥梁建设2015年第45卷第5期(总第234期)BridgeConstruction，Vo1．45，No．5，2015(TotallyNo．234)99文章编号：1003—4722(2015)05—0099—06公安长江公铁两用特大桥4号墩钢围堰施工技术杨齐海，何加江(中铁大桥局集团有限公司，湖北武汉430050)摘要：公安长江公铁两用特大桥主桥为(98+182+518+182+98)m的双塔双索面钢桁梁斜拉桥，4号桥塔墩采用变直径钻孔摩擦桩基础。4号墩基础施工采用双壁钢套箱围堰方案，钢围堰为圆端形结构，长68．2m、宽40．0m、高23．7m(分为2节，底节高16．0m

2、)，双壁厚2．0m。钢围堰底节在岸上制造，采用气囊断缆法下水，下水坡度从1：10调整为1：7，设置地锚、钢凳、底托板与底托架，并设置了48个规格为1．2m×8．5m的气囊；钢围堰下水自浮，待钢围堰稳定后，利用3艘拖轮联结编队进行长距离整体浮运，将钢围堰浮运至墩位处；在墩位处采用无导向船重锚锚碇系统进行快速精确定位。该桥钢围堰顺利下沉到位，经检测钢围堰最大平面偏差小于5cm，最大垂直度偏差小于1。关键词：公路铁路两用桥；斜拉桥；桩基础；钢围堰；气囊法下水；浮运；定位；桥梁施工中图分类号：U448．27；U445．55文献标志码：AConstructionTechniques

3、ofSteelCofferdamforPierNo．4ofGonganChangjiangRiverRail—cam—RoadBridgeYANGQi—hai。HEJia—jiang(ChinaRailwayMajorBridgeEngineeringGroupCo．，Ltd．，Wuhan430050，China)Abstract：ThemainbridgeofGonganChangjiangRiverRail—cum—RoadBridgeisasteeltrussgirdercable—stayedbridgewithdoublepylons，doublecablepl

4、anesandwithspanarrangement(98+182+518+182+98)m．ThefoundationforthepylonpierNo．4ofthebridgeistheoneoffric—tionalboredpilesofvariablediametersandwasconstructedbytheschemeofdouble—wallsteelboxedcofferdam．Thecofferdamisaround—endstructurethatis68．2mlong，4O．0mwideand23．7mhigh(dividedintotwolif

5、tswiththefirstliftbeing16．0mhigh)andthethicknessofthedoublewallsofthecofferdamis2．0m．Thefirstliftofthecofferdamwasmanufacturedonbank，launchedtotheriverbytheairbagsandbycuttingtheconnectingcables．Theslopeforlaunchingofthecofferdamwasadjustedfrom1：10to1：7，thegroundanchors，steelstands，basesu

6、pportplatesandbasesupportframeworkwerearrangedand48airbags，eachindimensionsof561．2m×8．5m，werearrangedaswel1．Thecofferdamfloatedintheriverbyitselfafteritwaslaunchedthere．Atthetimethecofferdambecamestable，3tugboatswereconnectedintoafleettointegral—lyfloatthecofferdamtothepiersiteinlongdist~

7、ince．Atthepiersite，thecofferdamwasrapidlyandaccuratelypositionedbytheheavyanchorsystemwithoututilizingtheguidingbarges．Thecofferdamwasfinallysmoothlysunkdowninplaceandtheinspectionshowedthatthemaximumplantoleranceofthecofferdamwaslessthan5cmwhilethemaximumverticalit