公铁混层布置双层箱桁组合梁建造技术

Construction Technology of Rail-cum-road Double-deck Steel Box-truss Composite Girder Bridge with Mixed Layer Layout

昌九高铁扬子洲赣江公铁大桥西支主桥为49+144+320+144+49 m双塔竖琴索面半漂浮体系斜拉桥,公铁混层对称布置,下层桥面中间布置双线无砟轨道高速铁路,两侧布置双向4车道城市主干路,上层桥面布置双向8车道城市快速路。主梁采用双层带挑臂箱桁组合梁,结构形式新颖,构造较复杂,为研究其受力性能,建立精细化实体节段模型开展局部应力分析,并结合沿途水运条件,研究了主梁运输方案及对应的安装方案。计算结果表明:带挑臂箱桁组合梁设计合理,上、下层桥面板局部应力较小,节点位置未出现较大的应力集中现象,公路桥面横桥向挠跨比满足规范要求;带挑臂箱桁组合梁桥面空间布置合理,具有良好的经济性,可为今后公铁混层合建桥梁提供借鉴。

The rail-cum-road main bridge of Changjiu high speed railway Yangzizhou Ganjiang Railway Bridge is 49+144+320+144+49 m twin-tower harp-cable surface semi-floating system cable-stayed bridge with symmetrical layout of mixed layer.A double-track ballastless high-speed railway is arranged in the middle of the lower deck,and a two-way 4-lane urban main road is arranged on both sides.The upper deck is equipped with a two-way 8-lane urban expressway.The main beam is composed of double layered steel box-truss composite beam with cantilever girder.The structural form is novel and the structure is complex.The overall design and construction details are elaborated in detail.In order to study the stress performance,establish a refined entity segment model to carry out local stress analysis.The transport scheme and corresponding installation scheme of the main beam are studied combined with the water transport conditions along the way.The results show that the design of the composite beam with cantilever box girder is reasonable,the local stress of the upper and lower bridge panels is small,there is no large stress concentration at the joint position,and the torsion span ratio of the bridge across the highway surface meets the standard requirements.The space arrangement of composite beam deck with cantilever box girder is reasonable and has good economy,which can provide reference for the future mixed-layer bridge construction.