基于极限状态法的帕德玛大桥上无砟轨道设计

Design of Ballastless Track on Padma Bridge Based on Limit State Method

研究目的:帕德玛大桥为6.15 km的公铁两用连续钢桁梁桥,是孟加拉帕德玛大桥铁路连接线的控制工程。为指导孟加拉帕德玛大桥上无砟轨道设计,本文针对帕德玛大桥的桥梁特点以及对其无砟轨道的工程需求,研究帕德玛大桥上无砟轨道设计方案,并基于极限状态法建立帕德玛大桥上无砟轨道梁板有限元模型,对帕德玛大桥上无砟轨道进行设计检算。研究结论:(1)综合考虑帕德玛大桥对无砟轨道的自重、高度、护轨安装、节间纵梁支座更换等工程需求,推荐采用单层、单元式长枕埋入式无砟轨道;(2)对于单元式结构,承载能力极限状态下基本组合对轨道结构配筋设计起控制作用;(3)对于长度3.882 m的道床板,以构造要求、受力和裂缝宽度为控制指标,道床板的纵向上层设置9根∅20钢筋,纵向下层设置16根∅20钢筋,横向上层设置20根∅20钢筋,横向下层设置22根∅20钢筋;(4)本文相关研究成果可为海外工程无砟轨道设计提供参考。

Research purposes: The Padma Bridge is a 6.15 km continuous steel bridge for highway and railway, which is a control project for the Padma Bridge Rail Link Project in Bangladesh. In order to guide the design of the ballastless track on the Padma Bridge in Bangladesh, this paper studies the design scheme of the ballastless track on the Padma Bridge based on the bridge characteristics of the Padma Bridge and the engineering requirements for its ballastless track, and based on the limit state method, the finite element model of the beam and slab of the ballastless track on the Padma Bridge is established, and the design and calculation of the ballastless track on the Padma Bridge are carried out.Research conclusions:(1) Considering the engineering requirements of Padma Bridge for the weight and height of ballastless track, guard rail installation on ballastless track, and replacement of bearings for stringers, it is recommended to adopt single-layer, unit long sleeper embedded ballastless track.(2) For the unit structure, the basic combination under limit state of the bearing capacity controls the track structure reinforcement design.(3) As for the track slab length of 3.882 m, taking structural requirements, force and crack width as control indicators, 9 ∅20 steel bars are installed on the upper longitudinal layer of the track bed slab, 16 ∅20 steel bars are installed on the lower longitudinal layer, 20 ∅20 steel bars are installed on the upper horizontal layer, and 22 ∅20 steel bars are installed on the lower horizontal layer.(4) The research results can provide references for the design of ballastless tracks in overseas projects.