港珠澳大桥非通航孔85m连续组合梁桥施工关键技术

Key Construction Techniques for 85m Non-navigational Channel Continuous Composite Girder Bridge of Hongkong-Zhuhai-Macao Bridge

港珠澳大桥浅水区非通航孔桥为11联双幅85m连续组合梁桥,基础采用钢管复合桩,承台及墩身采用预制拼装结构,承台深埋于海床内,上部结构采用组合梁结构。桥位处地质复杂、环境恶劣,利用"小天鹅"号运架双体船搭载整体导向架系统,实现复合桩基础钢管三次定位,精确控制钢管插打;承台+底节墩身整体预制时钢筋按4个模块分别绑扎,组拼成整体后应用自动化开合模板浇筑混凝土,并采用裂纹控制技术及防腐措施;承台+底节墩身预制构件采用"小天鹅"号运架一体船运输、起吊下放进入锁口钢套箱围堰内,通过复合桩桩顶三向调节装置精确定位安装;组合梁的钢梁在工厂加工成板单元后,船运至中山预制场进行整孔组拼,混凝土桥面板采取纵向分块、横向整幅预制,二者结合成组合梁后由"天一号"运架一体船逐片吊装。

The non-navigational channel bridge in the shallow water area of Hongkong-ZhuhaiMacao Bridge is a continuous composite girder bridge with separated left and right decks.The bridge has 11 continuous units of spans of 85 m.The foundation of the piers is formed of concretefilled steel tubular piles,the pile caps and pile shafts were prefabricated and assembled in the workshop,and the pile caps were deeply buried in the seabed.The superstructure adopts composite girder structure.Complicated geological condition and harsh environment render the bridge site quite challenging for construction.The Crane Little Swan,a catamaran used to lift and erect girders,was employed to carry the overall guiding frame system,to realize three times of positioning of the composite foundation steel tubes and precisely control the driving of the steel tubes.The pile cap and the bottom lift of the pier are monolithically prefabricated,during the manufacture of which,the reinforcement was divided into four modulus,each being individually bonded,then assembled to a whole,afterwards,the automatic retractable formwork is used to cast concrete.The crack control technique and corrosion protection measures are used.The prefabricated components of the monolithic pile cap and bottom pier lift are transported by the Crane Little Swan,then hoisted and lowered into the interlocked suspension steel box cofferdam,and precisely positioned and installed by the three-directional adjusting devices on pier tops.The steel structure of the composite girder was firstly fabricated to plate units in the workshop,then floated to the prefabrication yard in Zhongshan to be assembled span by span.The concrete slabs are longitudinally divided into blocks and transversely prefabricated as a whole,when the steel structures and concrete slabs are combined to form a composite girder,the Crane Tianyi,a ship capable of lifting and erecting girders,is used to lift the girders section by section.