大跨双层公铁两用钢箱拱桥设计关键技术

Key Techniques for Design of Road/Rail Long Span Double Deck Steel Box Arch Bridge

成贵高铁宜宾金沙江公铁两用桥主桥为主跨336 m双层桥面钢箱系杆拱桥,是世界上首座高铁在上层、公路在下层的分离式桥面公铁两用钢箱拱桥,两层桥面高差32 m。在钢箱拱上采用将公路柔性吊索内穿于铁路刚性吊杆并独立锚固于拱肋的技术,解决了双层桥面吊杆布置和锚固难的问题;采用水平钢箱连杆连接拱肋与铁路桥面的技术,解决了铁路桥面短刚性吊杆疲劳问题;拱墩固结段的钢-混接头采用直接承压式,用高强锚栓提供预压力的方式解决了钢-混接头受力复杂的难题;采用正交异性钢桥面板、底层超高性能混凝土和面层改性沥青的组合桥面铺装体系,有效降低了钢桥面的应力和疲劳开裂风险,延长使用寿命;采用八边形截面的刚性吊杆有效改善了吊杆的涡振性能,并对大桥抗风性能进行了风洞模型试验。风-车-桥耦合动力分析结果表明桥梁的动力性能和列车过桥时的安全性与舒适性均满足规范要求。

The main bridge of Yibin Jinsha River Combined Bridge of Chengdu-Guiyang High-speed Railway is a double deck steel box tied arch bridge with 336 m main span.It is the first highway-railway steel box arch bridge of separated decks in the world,with the upper deck for high-speed railway and the lower deck for highway.The height difference between the two decks is 32 m.On the steel box arch,the new technology of using the flexible sling of the highway to penetrate the rigid suspender of the railway and anchor it to the arch rib independently is applied to solve the problem of difficult suspender arrangement and anchoring on the double decks.The technology of connecting arch rib and railway bridge deck with horizontal steel box connecting rod is adopted to solve the fatigue problem of short rigid suspender on railway bridge deck.The steel-concrete joint in the consolidation section of arch pier adopts direct compression type,and high-strength anchor bolt is used to provide preload,which solves the problem of complex stress of steel-concrete joint.The composite deck pavement system of orthotropic steel deck,bottom ultra-high performance concrete and surface modified asphalt is adopted to effectively reduce the stress and fatigue cracking risk of steel deck and prolong its service life.The vortex vibration performance of the rigid suspender with octagonal section is effectively improved,and the wind tunnel model test is carried out on the wind resistance performance of the bridge.The results of wind-vehicle-bridge coupling dynamic analysis show that the dynamic performance of the bridge and the safety and comfort of the train passing the bridge meet code requirements.