【作者】 夏飞龙；

【导师】 李永乐；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2013， 硕士

【摘要】 随着我国高速铁路的快速发展,越大江、大河的大跨度板桁斜拉桥的修建也越来越多。无砟轨道由于其具有良好的结构恒定性、稳定性、耐久性、少维修性、经济性等技术特点,近年来在国内外高速铁路上得到了广泛的应用。大跨度板桁斜拉桥和无砟轨道由于其自身结构特性,在列车荷载作用情况下两者之间可能存在静力匹配和动力适应的问题。针对大跨度板桁斜拉桥无砟轨道静动力特性的研究,国内外较为少见。因此,有必要对大跨度板桁斜拉桥无砟轨道静动力特性开展研究。本文以有限元软件ANSYS为静力计算工具,以显式动力学分析程序LS-DYNA为动力计算工具,以LS-PREPOST为后处理工具,对大跨度板桁斜拉桥无砟轨道静动力特性进行研究。首先,建立三节间梁-体-壳局部精细化ANSYS模型,将板桁斜拉桥和无砟轨道作为一个系统研究其静力学特性。其次,建立了五种不同布置方式的道床板、底座板有限元模型。分析和对比了不同道床板布置情况下桁架节间内的轨道整体刚度及其变化规律,对比了大跨度板桁斜拉桥上、普通线路上及混凝土简支桥上无砟轨道整体刚度之间的差异,明确了大跨度板桁斜拉桥无砟轨道整体刚度的特点。采用非线性弹簧单元和接触单元两种方法模拟弹性减振垫层与道床板的接触关系,计算了节间内不同位置处道床板局部脱空的可能性、脱空量和脱空区域,对比了不同道床板布置情况下的脱空量和不同弹性减振垫层刚度组合情况下的脱空量,并提出了降低脱空量的优化方案。再次,利用显式动力分析方法,建立了列车-无砟轨道-大跨度板桁斜拉桥局部桥面系垂向振动模型,将车、轨、桥三者作为一个交互作用、协调工作的耦合振动系统。最后分析了桥面板、道床板局部振动在节间内的分布规律和特性,研究了大跨度板桁斜拉桥设置底座板的必要性,对比了不同车速对桥面板、道床板振动的影响,并通过时域分析和频谱分析提出了合理的弹性减振垫层刚度取值。静力分析结果表明,大跨度板桁斜拉桥正交异性桥面板刚度不均匀对轨道整体刚度有一定的影响,无砟轨道自身结构不连续对轨道整体刚度在纵向位置上的均匀性影响显著。大跨度板桁斜拉桥无砟轨道设计时应充分考虑桥梁结构的影响,以保证轨道结构与桥梁结构的匹配性。跨越主横梁处的道床板在板端区域存在与底座板脱空的可能性,最大脱空量与荷载作用位置及道床板布置形式有关,宜优先选择道床板在主横梁处断开的布置方式。弹性减振垫层采用两端刚度小、中间刚度大的布置方式能够明显的降低脱空量和脱空区域。动力分析结果表明,大跨度板桁斜拉桥无砟轨道桥面系设计中沿纵向采用密横梁体系,在横向设置多道纵梁,这种结构形式能够降低桥面板的局部振动。底座板的设置明显的降低了轨道结构下方区域、两条线路纵梁之间区域桥面板的加速度响应以及接缝边缘道床板的加速度响应。轨道结构下方桥面板的最大竖向加速度峰值随车速提高而增大,道床板的最大竖向加速度峰值随车速提高而增大。列车设计速度较高时,道床板的长度应尽量与节间长度匹配,避免出现道床板跨越主横梁的情况。综合时域分析和频谱分析结果,弹性减振垫层刚度宜优先选择0.05N/mm3。本文工作对于进一步研究大跨度板桁斜拉桥无砟轨道的静动力特性具有一定的参考价值,为大跨度钢桥无砟轨道的设计提供依据。更多还原

【Abstract】 With the vigorous development of high-speed railway, more and more long-span plate-truss cable-stayed bridges have been or will be built across the Yangtze river or Yellow River. The ballastless track has been widely used on high-speed railway both at home and abroad in recent years, due to its technical characteristics like good structure constancy, stability, durability, less maintenance and economy. Static matching and dynamic adaption problems occur under train loads between the long-span plate-truss cable-stayed bridge and the ballastless track, due to their structural characteristics. However, studies on static and dynamic properties of the long-span plate-truss cable-stayed bridge with ballastless track, are rare both at home and abroad. Therefore, it is necessary to carry out research on these.This article studied static and dynamic properties of long-span plate-truss cable-stayed bridges with ballastless track, using finite element software ANSYS as the static calculation tool, and explicit dynamic analysis program LS-DYNA as the dynamic calculation tool, and LS-PREPOST3.2as the post-processing dynamic calculation tool.Firstly, established a three-inter beam-solid-shell local refined ANSYS model, regarding the plate-truss cable-stayed bridge and ballastless track as a system to study its static properties.Secondly, set up five track bed slab and support layer finite element models arranged in different ways. And analysis and compared orbits’integral stiffness and their change law within the truss internodes under different arrangements of track bed slabs, and discussed the differences of orbits’integral stiffness between long-span plate-truss cable-stayed bridgess with ballastless track and that on normal lines and concrete simply-supported bridges with ballastless track, then found out the characteristics of integral stiffness of the long-span plate-truss cable-stayed bridges with ballastless track.Using Two methods, that is, nonlinear spring element and contact element, to simulate the contact relationship between elastic damping cushion layer and track bed slab, and calculate the possibility of partial void, void volume and void range at different places within the truss internodes. Then, compared the void volume which is in different track bed slab layout conditions and which is in different elastic damping cushion stiffness combination cases. At the same time, put forward some optimization schemes to reduce void volume.Thirdly, using the explicit dynamic analysis method, established the vertical vibration model of the local deck system of train-ballastless track-long-span plate-truss cable-stayed bridge, and taking trains, railways and bridges as a coupled vibration system of interaction and coordination.Finally, analyzed the distribution and features of local vibration of road track bed slab and bridge panel within the internodes, and studied the necessarity of setting the support layer on long-span plate-truss cable-stayed bridges, then compared the influence of different train speeds on the vibration of bridge deck and the track bed slab, and optimized the stiffness of elastic damping cushion layer through time domain analysis and frequency domain analysis.The static analysis results showed that, uneven stiffness of the long-span plate-truss cable-stayed bridge orthotropic bridge deck had some influence on orbits’integral stiffness, and the structural discontinuity of ballastless track significantly affected the uniformity of orbits’integral stiffness in vertical position. The design of long-span plate-truss cable-stayed bridge with ballastless track should take full account of the impact of the bridge structure, in order to ensure the matching of track structure and bridge structure. It’s possible that there may exist void between road track bed slab across the main beams at the board terminal region and the support layer. The maximum void volume was related to load position and track bed slab layout form, so we should give priority to the layout that track bed slabs were disconnected at the main beams. The layout of elastic damping cushion layers using small stiffness on both ends and big stiffness on the middle can obviously reduce void volume and void range.The Dynamic analysis results show that the long-span plate-truss cable-stayed bridge floor system with ballastless track adopted in longitudinal beam system, girder set between transverse spacing can reduce the local vibration of bridge deck. Setting support layer significantly reduced the acceleration response in the areas beneath the track structure, between the longitudinal beam bridge deck and on the edge of the track bed slab juncture. The peak value of vertical acceleration of the bridge panel at the bottom of track structure increases with the increase of train speed. At high train design speed, the length of the track bed slab should match with intemodes length, avoiding the case that track bed slab across the main beam. Based on the analysis of time domain and frequency domain, the stiffness of elastic vibration isolation cushion should be preferred0.05N/mm3This article has the certain reference values on further studies about the static and dynamic properties of long-span plate-truss cable-stayed bridge with ballastless track. Besides, this paper also provides basis for the future design of long-span steel bridge with ballastless track.更多还原