连续梁拱桥斜坡预制变坡多点同步顶推施工关键技术研究

Research on Key Technology of Multi-point Synchronous Incremental Launching Construction for Precast Slope of Continuous Beam Arch Bridge with Variable Slope

顶推施工具有对桥下交通干扰小的工艺特点,近年来在跨既有铁路等截面桥梁施工中得到了广泛应用。南昌市双港大街上跨昌北车站立交桥改造工程,为国内首座采用斜坡预制、变坡多点同步顶推施工工艺的非对称连续梁拱桥。施工中提出“分层浇筑梁体—凿穿底板—安装定位支架”的方法安装钢拱脚,有效地解决了斜坡预制钢拱脚定位难的问题;提出“梁中轴线挂铅锤—地面铺网格纸”的方法,施工中不间断标定梁体横向偏移,解决了跨铁路非对称结构顶推施工无法带电监测的难题;借助搁墩、调平垫块及辅助千斤顶,实现了变坡顶推导梁上墩工艺及落梁技术。施工中采取简易而高效方法,保证了跨车站非对称连续梁拱桥变坡顶推的施工质量和施工安全,为同类桥梁顶推施工监测提供了参考。

In recent years,incremental launching method has been widely used in the construction of bridges with constant cross-section across existing railways because of its technological characteristics of minor traffic interference under the bridge.The reconstruction project of the overpass across Changbei Station on Shuang Gang Street in Nanchang is the first asymmetric continuous beam arch bridge in China,which adopts slope prefabrication and multi-point synchronous incremental launching construction with variable slope.In the construction,the method of pouring the beam body in layers-drilling through the bottom plate-installing the positioning bracket is put forward to install the steel arch foot,which effectively solves the problem of difficult positioning of the prefabricated steel arch foot on the slope.The method of hanging plumb hammer on the central axis of the beam and laying grid paper on the ground can continuously calibrate the lateral deviation of the beam during construction,thus solving the problem that the incremental launching construction of asymmetric structures across the railway cannot be monitored on line;with the help of pier,leveling pad and auxiliary jack,the pier-on-beam technology and beam-off technology are realized on variable slope top.Efficient and simple methods are adopted in the construction,which ensures the construction quality and safety of variable slope jacking of asymmetric continuous beam arch bridge across stations,and provides reference and experience for the monitoring of incremental launching construction of similar bridges.