铁道建筑

千米级高速铁路桥梁温度变形易影响轨面平顺性，现有设计方法适配性不足。以巢马铁路马鞍山公铁长江大桥为依托，计算桥面温变变形后提出四种纵断面设计方案，通过耦合动力仿真分析不同方案行车性能。研究结果表明：四次曲线方案线形平顺性最优，跨中最小曲率半径达248756m，其车-线及车-线-桥耦合工况下的车体垂向加速度分别为0.11m/s²、0.31m/s，但该方案施工难度大，目前尚无工程应用实例。单人字坡方案计算的车-线及车-线-桥车体垂向加速度分别为0.23m/s、0.39m/s，满足设计规范要求，且具备桥面排水便捷、施工简便的优势；双人字坡方案计算的车体垂向加速度分别为0.24m/s、0.45m/s，存在施工繁琐、排水设计复杂等不足；中部平坡方案计算的车体垂向加速度分别为0.22m/s、0.39m/s，易产生桥面积水，且变坡点设置难度较高。综合行车性能与工程可行性，推荐马鞍山公铁长江大桥采用单人字坡纵断面方案：坡度3‰，变坡点设于Z4号主塔，跨中竖曲线半径30000m，研究成果可为同类桥梁设计提供支撑与借鉴。

Temperature deformation of kilometer-scale high-speed railway bridges tends to affect track surface regularity， and existing design methods lack adequate adaptability. Based on the Maanshan Yangtze River Bridge of the Chaohu–Maanshan Railway， this study calculates the temperature-induced deformation of the bridge deck and proposes four longitudinal profile design schemes. Coupled dynamic simulation is conducted to analyze the running performance of different schemes. The results show that the quartic curve scheme features the optimal alignment regularity， with a minimum curvature radius of 248，756?m at mid-span. The vertical car body accelerations under the train-track and train-track-bridge coupled conditions are 0.11?m/s and 0.31?m/s respectively. However， this scheme entails high construction difficulty and has no engineering application cases to date. For the single broken grade scheme， the vertical car body accelerations under the two coupled conditions are 0.23?m/s and 0.39?m/s respectively， which meet the requirements of design codes. Meanwhile， it boasts the advantages of convenient bridge deck drainage and simple construction. The double broken grade scheme yields vertical car body accelerations of 0.24?m/s and 0.45?m/s respectively， and suffers from drawbacks such as complex construction and sophisticated drainage design. The central flat grade scheme produces vertical car body accelerations of 0.22?m/s and 0.39?m/s respectively， which is prone to bridge deck ponding and involves difficulties in setting grade change points. Considering both running performance and engineering feasibility， the single broken grade longitudinal profile scheme is recommended for the Maanshan Yangtze River Bridge: a grade of 3‰， grade change point located at the No.?Z4 main pylon， and a mid-span vertical curve radius of 30，000?m. The research findings can provide support and reference for the design of similar bridges.