秭归长江公路大桥钢-混凝土结合梁安装技术

Installation Techniques for Steel-Concrete Composite Girder of Zigui Changjiang River Highway Bridge

秭归长江公路大桥为主跨519 m(计算跨径)全推力中承式无铰钢箱桁架拱桥,钢-混凝土结合梁设计为“平面框架式钢梁+预制混凝土桥面”结构体系。桥梁位于三峡库区,跨越长江主航道,两岸地势险要、场地狭窄,且受峡谷复杂风场影响。结合桥梁结构及建造环境特点,钢梁进场采用陆上、水上多样化的运输方式,在江面航道外侧设定位船实现运输船舶快速定位;拱上立柱区钢梁采用先安装横梁再逐跨安装纵梁及次横梁;吊杆区钢梁采用先间隔架设整节段再散件安装跨间梁,最后在跨中无应力合龙;混凝土桥面板采用“拱上提升站起吊+梁面平车纵移+梁面龙门吊机复位”多设备接力安装。该桥采用的多项施工关键技术解决了不利条件下的施工难题,实现了钢-混凝土结合梁顺利安装。

The Zigui Changjiang River Highway Bridge is a half-through hingeless steel box truss arch bridge of full thrust and the main span measures 519 m(calcultated span length).The deck of the bridge consists of plane cellular steel girder and precast concrete slabs.The bridge is located in the Thee Gorges Reservoir area and crosses the main navigation channel of Changjiang River,the construction of which is challenged by the hazardous steep-sided ravine,limited construction space and complex wind conditions.Given the structural characteristics of the bridge and environmnets at the bridge site,the steel girders were transported by both vehicles and ships to the construction site,and positioning ships were anchored besides the navigation channel for the fast positioning of girder transporation ships.For the deck supported on spandrel columns,the cross beams were installed prior to the span-by-span installation of stringers and secondary cross beams.For the deck supported by hangers,the monolithic steel girder segments were first installed alternately,which was subsequently followed the built-up of individual members of beams in between as well as the stress-free midspan closure.The precast concrete slabs were installed by a relay race of hoisting,longitudinal moving and resetting carried out by arch-mounted lifting cranes,delivery trolleys and gantry crane on the deck,respectively.The utilization of these proposed techniques resolved various construction complexities and realized the smooth installation of the steel-concrete composite girder.