考虑轨道静态变位的简支梁竖向刚度限值研究

研究目的:高速铁路桥梁在徐变、温度、桥墩沉降等作用下会发生多种静态变位,进而影响轨道平顺性与列车走行舒适性和安全性。本文将桥梁静态变位与列车活载下的动态变形统筹考虑以获取简支梁竖向刚度限值,使得列车在一定轨道静态变位的简支梁上具有优良的走行性。研究结论:(1)小于活载挠度的初始桥梁上拱对列车走行性有利,而初始下挠、桥墩不均匀沉降、轨面随机不平顺及过大的初始上拱均为不利因素;(2)规范在桥梁刚度的限值上留有一定富余度,跨度越短、车速越高则对桥梁静态变位的要求越严格;(3)设计时可在预测桥梁静态变位的基础上合理选择桥梁刚度,养护时则可根据当前桥梁的实际刚度和静态变位组合采取整治措施;(4)本研究成果可为铁路桥梁刚度设计、运营维护及规范修订提供参考。

Research on the Threshold of Vertical Stiffness of Simply Supported Girders Considering Static Deformation of Track

Research purposes:Static deformations may occur in high-speed railway bridges due to creep,temperature and pier settlement,which affect track regularities and driving comfort and safety of the trains.The static deformation of bridges and the dynamic deformation under the live load of the train are taken into consideration to obtain vertical stiffness threshold of simply supported girders which maintains good riding quality of the trains.Research conclusions:(1)Initial upward flexure of bridges is favorable for the riding comfort of the trains when it is smaller than the bridge deflection under live load,while initial downward flexure,uneven settlement of the bridge pier,random irregularity of the rail surface and excessive initial upward flexure are all unfavorable factors.(2)Certain safety redundancy was reserved in the threshold of vertical stiffness of bridges in some codes,and the requirement for static displacement of bridge was stricter for shorter spans and higher operation speeds.(3)In the design phase,the bridge stiffness can be reasonably determined according to the predicted static deformation of the bridges;while in the operation stage,reasonable decision can be made based on the actual stiffness and static deformations of the bridges.(4)The research results can provide reference for the design,operation and maintenance of railway bridge stiffness and the revision of specifications.