斜拉桥长大节段组合式主梁悬臂施工技术研究

Cantilever Construction Technology of the Combined Main Girder with Long Segment for Cable⁃stayed Bridge

鲁巴跨海大桥主航道桥为双塔双索面混凝土斜拉桥,大桥主梁为π形混凝土组合式主梁,标准节段长10.2m、宽17.3m、中心高2.5m;主梁斜拉索锚固块及横向横梁为预制装配式构件,边主梁及桥面板为现浇混凝土构件,各主要构件通过横向预应力连为一体。以该桥主梁悬臂施工为工程背景,从质量控制、施工计划、施工成本3个方面对主梁2种施工方案进行对比,最终确定适合本桥主梁施工的挂篮方案,可有效降低临时结构自重对已浇筑节段混凝土产生的附加应力影响,降低工程造价;同时,通过对2~15号主梁节段采用新型桁架式牵索挂篮施工进行专项设计,解决了主梁节段长、自重大、预制装配式构件安装精度要求高、节段施工周期长的难题。

The main navigation channel bridge of Lupar Bridge is a double⁃tower and double⁃cable plane concrete cable⁃stayed bridge.The main girder is aπtype concrete combined girder.The standard section length is 10.2m,the width is 17.3m,and the center height is 2.5m.The cable anchor block and crossbeam of the main girder are prefabricated components,the side girder and deck are cast⁃in⁃site concrete members,and the main components are connected together by transverse prestress.This paper takes the cantilever construction of the main girder of the bridge as the engineering background,and compares two construction schemes of the main girder from three aspects of quality control,construction plan,and construction cost.Finally,the suitable cable hanging basket scheme for the construction of the main girder of the bridge is determined,which can effectively reduce the additional stress caused by the self weight of the temporary structure on the poured section concrete and reduce the engineering cost;At the same time,a special design is carried out for the construction of No.2 to No.15 main girder sections using a new type of truss type cable hanging basket,which solves the problems of long length,heavy weight,high installation accuracy requirements for prefabricated components,and long construction period of the main girder sections.