140 m大跨度钢箱系杆拱桥预拱度控制关键施工技术

Key Construction Technology for Pre-camber Control of 140 m Long-span Steel Box Tied Arch Bridge

无砟轨道具有可靠的稳定性和高平顺性,对线路的平顺度要求较高。以松福路1号特大桥1-140 m钢箱系杆拱桥为工程背景,开展桥梁铺设二期恒载之前预留后期变形的预拱度研究。支架施工前所设预拱度既要包括恒载位移和支架变形,又要包括无砟轨道施工产生的下挠。本文从支架施工和无砟轨道施工两个阶段分析桥梁的预拱度。依据MIDAS数值分析结果,对比支架现场施工阶段实测变形数据,两者吻合度较好。剩余预拱度为桥面板、无砟轨道底座、道床及附属工程施工预留。为更好地控制无砟轨道施工时的预拱度,采用先进行左线施工,再进行右线施工,一次浇筑完成的施工方法。混凝土浇筑时必须从两端向中间对称同步进行,防止加载不均导致梁部下挠值与数值模拟预拱度值不匹配。

Ballastless track has reliable stability and high smoothness,which requires high smoothness of bridges.This paper takes the 1-140 m steel box tied arch bridge of No.1 Songfu Road Bridge as the engineering background to study the pre-camber of reserving the late deformation before laying the bridge under the second dead load.The pre-camber set before the construction stage of the bracket should include not only the dead load displacement and the deformation of the bracket,but also the deflection caused by the construction of ballastless track.Pre-camber of the bridge is analyzed from two aspects:support construction stage and ballastless track construction stage.Based on the MIDAS numerical analysis results,it is found that the deflection of the beam is basically in accordance with the measured data and the calculation.The remaining camber is reserved for the construction of bridge deck,ballastless track base,ballast bed and ancillary works.In order to better control the pre-camber in ballastless track construction,the left-line construction is carried out before the right-line construction,and the construction is completed at one time.When the concrete is poured,it must be synchronized from both ends to the middle symmetrically to prevent uneven loading from causing the mismatch between the deflection of the beam and the pre-camber value calculated by the numerical modeling.