山区单跨回转缆悬索桥猫道设计施工关键技术OA

To summarize the key technical experience in catwalk construction for rotating-cable suspension bridges under complex mountainous conditions,this paper took the Three Gorges Bridge on the Yellow River(a single-tower and single-span rotating-cable steel truss girder suspension bridge with a main span of 540 m)as the engineering background.A two-span continuous catwalk without wind-resistant cables was used as the superstructure construction platform,and three major technical countermeasures in catwalk design and construction were systematically elaborated.In the 146 m cable-girder intersection area on the north side,the catwalk and the steel girder collided,and setting up the looping anchorage system for a catwalk was difficult.To address these problems,brackets and anchor beams were set at the front end of the anchorage for anchoring catwalk cables.Following the schedule of girder erection,the profile-shifted steel frame on the north side was installed in two stages to realize the avoidance of the catwalk from the steel girder.The bridge site was in the Three Gorges Reservoir area of the Yellow River,and the construction condition of the catwalk was poor.The pilot cable of Dyneema rope was pulled across the river from cable tower to looping anchorage by using the unmanned aerial vehicle(UAV)+sag control method.The single hook hanging method was used to erect the portal support cable,while the double-suspension-ring method was used to erect the catwalk load-bearing cable.Construction practice shows that this method has the advantages of low traction requirements,convenient sag control,and high construction efficiency,and exhibits good adaptability to bridge erection construction in the steep valley environment in mountainous areas.