单索面斜拉桥高支架施工钢箱梁支点反力与线形控制研究

The Research to High-support Construction Steel Box Girder ReactionForce And Alignment Controlling of Single Cable Plane Cable-stayed Bridge

大榭第二大桥为单索面钢箱梁斜拉桥,主墩区和边跨钢箱梁采用高支架施工。为了保证支架安全,减小钢箱梁扭曲变形,确保主梁线形满足精度控制要求,提出了高支架施工精细化控制方法,采用压力传感器监测高支架上各梁段施工过程中的反力变化,并与理论值进行比较。研究表明,高支架上钢箱梁段初调完成后,各支点反力相差较大,往往超过30%,对支点反力进行调整后,上、下游支点反力差值可以控制在5%以内;从而减小了单索面钢箱梁由于支点反力不匀导致的扭转变形,降低了高支架施工的风险;同时高支架上钢箱梁段上、下游测点相对高差绝大部分控制在10mm以内,说明通过对施工过程中钢箱梁支点反力的调整,有效地起到了控制钢箱梁线形的作用。

Daxie second bridge is a cable z-stayed structure with single cable plane and steel box girder, and the method of high-support construction is used in main pier areas and side span areas. In order tO guarantee support safe, reduce distortion deformation of steel box girder and ensure alignment of main girder to satisfy the control requirement, this paper proposes a more accurate method in high-support construction control, using pressure sensor to monitor the reaction force changes of the girders on the high support during the construction and compared with the theoretical value. The research shows that the difference among the reaction forces are larger after the initial adjustment of high-support steel box girder, and is often more than 30%. After adjusting the reaction force, the difference between the upstream and downstream reaction forces is controlled within 5 %, thus to avoid torsional deformation of the single cable plane steel box caused by uneven reaction force. Meanwhile, relative height difference of measuring point at high-support girder between the upstream and downstream is controlled substantially less than 10 mm, which means the reasonable adjustment to reaction force of steel box girder during construction stage plays a effective role in the alignment control of steel box girder, thereby, the risk of high-support construction can be reduced.