超高性能混凝土在大跨度铁路桥梁钢桥面铺装中的应用

Application of UHPC to Steel Deck Pavement of Long-Span Railway Bridge

铁路桥钢桥面铺装主要作用是保护钢桥面免受道砟的磨损与雨水的侵蚀,为提高铁路钢桥面铺装的使用寿命,减少中期维修,对铁路钢桥面超高性能混凝土(UHPC)组合桥面铺装体系进行研究。以沪通长江大桥主航道桥为背景工程,制作带UHPC铺装层的正交异性钢桥面板单U肋梁模型进行抗水渗性能试验,并结合实桥进行UHPC组合桥面铺装体系设计和施工工艺研究。结果表明:UHPC组合桥面体系在无裂缝时抗渗性能满足使用要求,可有效保护钢板免受雨水侵蚀,带裂缝的组合桥面,运营过程中裂缝会逐渐闭合,阻止雨水进一步渗透,具有较强的抗渗能力储备;为避免新浇混凝土开裂,UHPC应严格按规范流程施工,施工温度宜选择15~25℃,浇筑后应及时覆膜保湿养护。

The main function of the steel deck pavement of railway bridge is to prevent the steel deck from abrasion induced by ballasts as well as rainwater invasion.To improve the service life of the steel deck pavement of railway bridge and reduce the mid-term maintenance,the ultra-high performance concrete(UHPC)composite deck pavement system for the railway bridge is studied.The main navigational channel bridge of Hutong Changjiang River Bridge is taken as an example project.A model of orthotropic steel deck plate girder with single U rib and UHPC pavement was prepared to test the impermeability of the UHPC pavement,and combined with the real bridge,the design and construction techniques of the UHPC composite deck pavement system was studied.The results show that the UHPC composite deck pavement system can meet the waterproofing requirements when no cracks occur,and can effectively prevent the steel plates from rainwater invasion.For the composite deck with cracks,the cracks will gradually close in the service period,and the UHPC deck pavement can further prevent the infiltration of rainwater and have a large impermeability margin.To prevent the cracking of newly-cast concrete,UHPC should be cast strictly conforming to the norms prescribed in the code.The proper temperature for UHPC construction is about 15-25℃,and after casting,the UHPC pavement must be covered with membrane for curing.