武汉青山长江公路大桥北主墩钢围堰封底关键技术  

Key Base Sealing Techniques for North Main Pier Steel Cofferdam of Qingshan Changjiang River Highway Bridge in Wuhan

作　　者：胡海波[1,2] 周亚栋 张晶 HU Hai-bo;ZHOU Ya-dong;ZHANG Jing(China Railway Major Bridge Engineering Group Co.,Ltd.,Wuhan 430050,China;State Key Laboratory for Health and Safety of Bridge Structures,Wuhan 430034,China;China Railway Bridge Science Research Institute,Ltd.,Wuhan 430034,China)

机构地区：[1]中铁大桥局集团有限公司,湖北武汉430050 [2]桥梁结构健康与安全国家重点实验室,湖北武汉430034 [3]中铁大桥科学研究院有限公司,湖北武汉430034

出　　处：《桥梁建设》2021年第1期8-13,共6页Bridge Construction

基　　金：中国中铁股份有限公司科技研究开发计划课题(2016-重大-06);湖北省交通运输厅科技项目(2017-538-2-11)。

摘　　要：武汉青山长江公路大桥主桥为主跨938m的斜拉桥,北主墩基础采用哑铃形双壁钢套箱围堰(长103.8m×宽43.3m×高37.5m)施工。围堰封底采用C30混凝土,厚6.5m、方量约20000m3。封底施工中,在承台系梁范围内布置8根1.5m的钻孔桩作为封底施工辅助桩,与承台主体钻孔桩同期施工,在主体钻孔桩、辅助桩钢护筒外侧加焊28mm钢筋剪力环,以提高围堰封底可靠性;根据水下地形扫描绘制以围堰为中心的大范围河床高程图,采用抛填卵石吨袋、皮带运输机抛填卵石相结合的方法封堵围堰底口;将底节钢围堰分成7个区域,采用垂直导管法按区域编号顺序依次连续灌注封底混凝土,降低封底施工控制难度;在围堰外壁板布置15个振弦式应变计,实时监测围堰的受力,保证施工过程中围堰结构安全。The main bridge of Qingshan Changjiang River Highway Bridge in Wuhan is a cable-stayed bridge with a main span of 938m.The foundation of north main pier was constructed with the dumbbell-shaped double-wall steel box cofferdam measuring 103.8m(length)by 43.3m(width),37.5min height.The base of the cofferdam was sealed by concreting,a 6.5m-thick base layer was finally formed,consuming 20000m3 of C30concrete.8piles of 1.5mdiameter were installed in the tie beams region of pile cap to assist the base sealing construction,which was also in parallel with the construction of main bored piles.To improve the reliability of the base sealing layer of cofferdam,reinforced shear rings with 28mm diameter were added to the surface of main and auxiliary steel casings.The riverbed elevation was scanned and mapped.The base of the cofferdam was filled by riprapping and using belt conveyor for pebble delivery.To ease the construction,the base lift of steel cofferdam was divided into 7zones which were numbered for continuous concreting using vertical conduit method.15 vibrating wire strain gauges were distributed on the outer wall of the cofferdam for the real-time monitoring of its load bearing behavior and ensure the safety of cofferdam in the construction process。

关 键 词：斜拉桥 钻孔桩 双壁钢套箱围堰 封底混凝土 垂直导管法 施工技术 

分 类 号：U448.27[建筑科学—桥梁与隧道工程] U445.556[交通运输工程—道路与铁道工程]