济青客运专线铁路连续槽形梁拱桥设计研究

Study and Design of Continuous Groove Beam Arch Bridge of Jinan-Qingdao Passenger Dedicated Line

研究目的:高速铁路跨越城市立交道路及高速公路时,为不影响下方道路正常通行,减小线路路堤建设高度,降低工程成本,同时满足设计要求,可采用建筑高度较低的下承式连续槽形梁拱结构形式。本文以新建济南至青岛客运专线工程跨越改移青兰高速公路的(66.5+142+66.5)m连续槽形梁拱桥为背景,从结构尺寸、梁拱刚度等主要参数设计以及纵横向受力、剪力滞等方面展开研究,从而掌握该类结构的主要技术特点。研究结论:(1)桥面布置上比较灵活,通过人行道、电缆槽的最优布置,可以使桥面宽度最小,适当增加边主梁宽度、设置“马蹄”形构造、拱肋预埋段局部穿孔,可以有效解决拱脚构造带来的钢束布置空间不足问题;(2)拱轴线、拱肋截面形式、吊杆布置与常规箱形截面预应力混凝土连续梁拱相差不大,设计时可参考取值;梁拱刚度比主要影响拱肋及主梁的内力、残余徐变、短吊杆的吊杆力,将梁拱刚度比确定为36.0,主梁、拱肋各指标在合理水平;(3)剪力滞分析表明,边支点、边跨跨中、中支点、中跨跨中典型截面剪力滞系数分别为1.29、1.19、1.30、1.14,均大于常规箱形截面的规范计算值,为保证结构安全,槽形梁拱在设计中应采用基于实体模型计算的剪力滞系数;(4)目前连续槽形梁拱桥在高速铁路工程中应用较少,缺乏一定的设计理论与经验,本研究成果可为类似桥梁的设计提供参考。

Research purposes:When the high-speed railway crosses over the urban overpass road and expressway,in order not to affect the normal passage of the lower road,reduce the construction height of the railway embankment,reduce the engineering cost,and meet the design requirements,it can adopt the continuous trough beam-arch structure with lower building height.On the(66.5+142+66.5)m continuous groove beam-arch bridge across Qingdao-Lanzhou Expressway in the newly built Jinan-Qingdao passenger dedicated line project,the main technical characteristics of this kind of structure are mastered by studying the design of main parameters such as structural size,stiffness of beam-arch,longitudinal and transverse force behavior and shear lag.Research conclusions:(1)The bridge deck layout is quite flexible,and the bridge deck width can be minimized by optimizing the layout of pavements and cable grooves.Appropriately increasing the width of side girders,setting up"horseshoe"structure and partial perforation of arch rib embedded section can effectively solve the problem of insufficient space for steel bundle layout caused by arch foot structure.(2)The arch axis,arch rib section form and suspender arrangement are similar to those of the conventional box-section prestressed concrete continuous beam arch,which can be taken as reference in design.The stiffness ratio of beam to arch mainly affects the internal force,residual creep and suspender force.The stiffness ratio is determined to be 36.0,and the internal force index of beam and arch rib is maintained at a reasonable level.(3)The analysis of shear lag shows that the shear lag coefficients of typical sections in side fulcrum,side span,middle fulcrum and mid-span are 1.29,1.19,1.30 and 1.14,respectively,which are larger than the standard calculation values of conventional box section.In order to ensure structural safety,the shear lag coefficients calculated based on solid model should be adopted in the design of trough beam arch.(4)At present,the continuous trough beam-arch bridge is seldom used in high-speed railway project and lacks certain design theory and experience.The research results can provide important reference for the design of similar bridges.