城市轨道交通上跨铁路特大桥方案研究

Research on Scheme of Large Bridge Overpassing Railway in Urban Rail Transit

摘要:

武汉轨道交通7号线北延线工程上跨铁路桥需跨越多股铁路，受天河机场限高等因素影响，主桥设计为（86+2×156+86）m预应力连续梁桥。设计中通过增加梁高、调整预应力钢束布置减少梁体残余徐变变形，采用二次张拉竖向钢绞线预应力体系改善主梁腹板抗裂性能。为减小施工对既有铁路的干扰，采用转体施工方案，转体吨位达15 000 t。邻近铁路的基坑采用隔离桩支护，基坑开挖和桥梁施工各阶段既有铁路路基附加沉降均满足规范要求。

Abstract:

The bridge overpassing railway in Wuhan Rail Transit Line 7 North Extension Project needs to span the multiple railways. Affected by the high limitation of Tianhe Airport, the main bridge is designed as a (86 + 2 × 156 + 86)-m prestressed continuous beam bridge. In the design, the residual creep deformation of the beam is reduced by increasing the beam height and adjusting the arrangement of prestressed steel strands. The crack resistance of the main beam web is improved by using the twice-tensioning vertical steel strand prestress system. In order to reduce the interference of construction on the existing railways, the rotation construction scheme is adopted, and the rotation tonnage is up to 15 000 t. The foundation pit of adjacent railway is supported by isolation piles, and the additional settlement of the existing railway subgrade at all stages of foundation pit excavation and bridge construction meets the specification requirements.