温度应力在无缝线路设计中的计算分析

无缝线路轨道由于限制了钢轨的纵向自由伸缩,在环境温度变化下,钢轨中会产生较大的纵向力,可能导致产生严重后果。为保证无缝线路的强度和稳定,需要了解温度应力对无缝线路产生的影响及计算方法。本文分析了温度应力对无缝线路的影响并介绍了温度应力在无缝线路应用中的计算方法。     

新型无缝线路温度内力测试系统的研制

研究出无缝线路上钢轨在温度发生变化时轴向温度内力的一种有效检测手段,并提出了新颖的理论和方法.通过建立无缝线路轨道力学模型分析温度内力变化时侧向力及其作用位移的变化规律,研制了新型无缝线路温度内力测试系统,结合标定试验对上述规律进行了参数修正,最终实现对钢轨温度力的精确测试.此项技术在实践应用中取得良好效果.     

广义变分原理在高速铁路无缝道岔结构分析中的应用

在继承现有试验成果的基础上,将广义变分原理应用于铁路无缝道岔结构体系的分析,提出了一种新的铁路无缝道岔计算理论。建立了较为完善的计算模型,在假设钢轨纵向位移函数的基础上,计算了无缝道岔结构体系各部分的能量,通过广义变分法建立了结构体系的平衡方程,编制了计算程序,分析了固定辙叉无缝道岔钢轨温度力与位移。为无缝道岔计算理论和设计方法的研究开辟一条新途径。     

齿轨铁路轨道-简支梁桥相互作用及轨缝合理位置研究

齿轨铁路与桥梁的梁轨相互作用对行车安全和结构稳定均有重要影响。基于有限元理论,建立了齿轨(钢轨)-轨枕-桥梁-墩台空间耦合计算模型,分析了典型荷载作用下齿轨铁路轨道-简支梁桥相互作用。结果表明:简支梁桥上齿轨铁路梁轨相互作用强于常规桥上无缝线路,在列车纵向荷载作用下的钢轨纵向力、梁轨相对位移、墩顶纵向力、墩顶纵向位移等指标比常规桥上无缝线路大40%以上,建议增强轨道基础与梁体的约束作用,增大轨道结构纵向阻力,防止在列车纵向荷载作用下的轨道爬行。齿轨最大等效应力小于其容许应力,齿轨强度不是结构设计的控制指标。建议齿轨轨缝与梁缝错开布置,可有效避免齿轨轨缝变化过大。     

Ⅰ型双块式无砟轨道传力杆受力研究

随着我国高速铁路的不断发展,Ⅰ型双块式无砟轨道结构得到了广泛应用。由于Ⅰ型双块式无砟轨道是连续结构,当铺设在温度变化较大的线路上时,会出现严重的开裂和上拱问题。为了适应兰新二线大温度跨度、大温差的线路条件,考虑将道床板断开为单元板,并在伸缩缝处设置传力杆,以保证轨道结构竖向和横向的稳定性。该文主要用有限元法计算不同传力杆数目时轨道结构的应力和变形,来研究传力杆的力学性能并确定传力杆最佳数目,最终建议传力杆数目不少于4根。     

浅淡铺设无缝线路

无缝线路是轨道结构技术进行步的重要标志,一次性铺设无缝线路对路基有较高的要求。无缝线路铺设需在现场进行长钢轨的焊接、拉伸、锁定等工艺操作。     

浅谈无缝线路养护与维修

无缝线路也叫长钢轨线路,就是把若干标准长度的钢轨经焊接成为1000m~2000m长而铺设的铁路线路,它也是目前我国铁路线路的主要轨道形式之一。从无缝线路的基本特点出发,针对现场养护维修中存在的主要问题,着重介绍了无缝线路日常养护与维修工作的方式与方法,明确了维修养护工作的重点。     

地铁线路钢轨波磨安全限值研究

地铁线路钢轨波磨会恶化轮轨接触关系,引起轮轨冲击,降低车辆和轨道部件的使用寿命,影响车辆运行安全,大大增加维修工作量和运营成本。钢轨打磨可有效控制波磨,而确定钢轨波磨安全限值并制定打磨策略是实施钢轨打磨的关键步骤。建立一种地铁车辆—轨道耦合动力学计算模型,详细调查地铁钢轨波磨对车辆运行安全性的影响。基于车辆—轨道耦合动力学仿真计算和地铁车辆的运行安全评价指标,初步确定时速80 km/h地铁线路的钢轨波磨的安全控制限值。结果可为地铁线路的钢轨校正性打磨提供理论参考。     

基于实测数据的环线地铁钢轨波磨特征分析

介绍钢轨波磨现行的主要分类方法和评价标准。以某环线地铁为例,对全线不同线路条件和轨道类型的钢轨波磨进行检测,按照轨道类型、曲线半径、线路型式以及曲线高、低轨来对比分析钢轨波磨的典型特征;使用BS EN ISO 3095标准对钢轨波磨进行量化评价。结果表明,该线路波磨分布最广的为普通扣件轨道,300 m～400 m半径曲线轨道,缓和曲线以及低轨。钢轨波磨出现频次最高的为钢弹簧浮置板轨道,200 m～300 m半径曲线轨道,圆曲线和低轨。各种轨道类型上都存在25 mm～50 mm波长波磨,400 m半径曲线轨道上的波磨波长分布最广,圆曲线和缓和曲线上波磨波长分布特征基本相同。     

CRTSII型无砟轨道温度翘曲变形及其对车线动力响应的影响

以孝感北站附近综合工区内的轨道板为研究对象,对露天环境下的轨道板进行两天的温度测量。采用节点温度荷载的加载方式对轨道板温度场进行模拟,分析轨道板整体温度升降和温度梯度共同作用下轨道板的温度变形。轨道板的翘曲引起钢轨的垂向变形,将其作为附加轨道不平顺分析车线系统的动力性能,并以此为基础计算高速列车通过轨道板翘曲区段时的行车安全性问题。研究表明,CRTSII型板式无砟轨道结构轨道板温度翘曲变形分析主要考虑两个因素:温度梯度值大小;轨道板面温度与初温。温度梯度值越大,翘曲变形的最大竖向位移越大;相同温度梯度时,轨道板面温度越接近初温,翘曲变形的最大竖向位移越小。在温度荷载影响路段,各项动力指标较正常路段都有所增大,钢轨和轨道板的垂向振动加速度的增大尤为显著,行车安全性指标劣化。     

横向地震作用下震致钢轨几何不平顺研究

铁路运输作为抗震救灾的重要生命线,在抗震救灾期和灾后重建期承担了极其重要的运输任务,研究震致钢轨不平顺是保证震后行车安全的基础.该文以高速铁路CRTS Ⅱ型轨道-桥梁系统为对象,建立了有限元模型并开展了试验验证,从PEER强震数据库中筛选出40条和设计反应谱匹配程度最高的地震波并对有限元模型开展了非线性时程分析,研究了...     

Effects of maintenance operations on railway track's mechanical behaviour by field load testing

Deterioration of track causes variations in different mechanical parameters such as value and distribution of track vertical stiffness, which would change the way track mechanical components behave in service condition or maintenance operations. As a result, studying deterioration effects and that of maintenance operations such as tamping and dynamic stabilisation on the mechanical behaviour of both standard and deteriorated tracks could give a better picture of track condition and effectiveness of maintenance operations. In this paper, by carrying out static and dynamic tests and using 89 measurement sensors, the influence of mechanised maintenance operations on mechanical behaviours (strain, acceleration and displacement of rail and sleeper) of a high-deteriorated track and a low-deteriorated track is investigated. The tests were carried out in three different stages (before tamping, after tamping and after track dynamic stabilisation) under a passing train (a 6-axle locomotive and a 4-axle wagon) with 20-ton axle load. Observations indicate that track deterioration causes non-uniform track stiffness and load distribution along the track, such that rail heel strain time history under train loading changes from maximum tensional pattern under the wheels to maximum compressive pattern between two wheels of a bogie. Tamping and dynamic stabilisation cause a more uniform load distribution, which reduces strain and increases acceleration in rail and sleeper. Effects of these maintenance operations on sleepers are far more than that of rail. Deteriorated track is stiffer than low-deteriorated track; stiffness distribution is less uniform and its rails are subjected to less strain and acceleration.     

Moving element method for train‐track dynamics

This paper presents a new approach, called the moving element method, for the dynamic analysis of train‐track systems. By discretizing the rail beam on viscoelastic foundation into elements that ‘flow’ with the moving vehicle, the proposed method eliminates the need for keeping track of the vehicle position with respect to the track model. The governing equations are formulated in a co‐ordinate system travelling at a constant velocity, and a class of conceptual elements (as opposed to physical elements) are derived for the rail beams. In the numerical study, four cases of moving vehicle are presented taking into consideration the effects of moving load and rail corrugation. The method is shown to work for varying vehicle velocity and multiple contact points, and has several advantages over the finite element method. The numerical solutions compare favourably with the results obtained by alternative methods. Copyright © 2003 John Wiley & Sons, Ltd.     

基于轨检车振动问题的钢轨轮廓匹配方法研究

轨检车在进行检测过程中由于轨道不平顺引起的上下振动、左右摆动、倾斜等平面内三自由度随机振动,导致被检测钢轨轮廓图形与标准轮廓图形发生错位,无法进行钢轨轮廓高精度匹配,很难为钢轨磨损修复制定科学合理的策略。利用不共线的三点确定一平面原理,提出一种基于轨检车振动问题的钢轨轮廓匹配方法,对检测钢轨轮廓的位置信息进行先旋转再平移的坐标变换,彻底解决了轨检车在进行检测过程中由于轨道不平顺引起的振动问题,实现了钢轨轮廓的高精度匹配。该方法已经运用在轨道检测小车上,试验证明其匹配精度能达到微米级。     

浮置板轨道横向振动的谐响应分析

建立浮置板轨道横向运动的数值模型，并考虑钢轨的扭转变形，得到钢轨轨头部以及浮置板在谐振作用下的横向位移响应以及钢轨扣件、钢弹簧的支承力。同时在ANSYS中建立浮置板轨道的有限元模型，与数值模型相对比，得到的结果相吻合。对数值模型在不同激励力和不同的支承条件下进行谐响应分析，得到钢轨和浮置板在0-500Hz频段内的横向运动状态。     

轨道刚度对高速轮轨系统振动噪声的影响

高速铁路对环境的噪声污染是一个不可忽视的问题,在已建立的轮轨滚动噪声预测模型的基础上,以板式轨道为对象,研究了在轮轨表面粗糙度(随机短波激扰)的激励下,轨道刚度变化对高速轮轨系统振动及轮轨噪声的影响.结果表明:降低轨道刚度,可以有效降低轮轨系统400Hz以下频率的振动,但对400Hz以上的振动基本无影响,从而,对轮轨噪声也基本无影响.     

Stress intensity factors evaluation for through-transverse crack in slab track system under vehicle dynamic load

The stress intensity factors (SIFs) for through-transverse crack in the China Railway Track System (CRTS II) slab track system under vehicle dynamic load are evaluated in this paper. A coupled dynamic model of a half-vehicle and the slab track is presented in which the half-vehicle is treated as a 18-degree-of-freedom multi-body system. The slab track is modeled as two continuous Bernoulli–Euler beams supported by a series of elastic rectangle plates on a viscoelastic foundation. The model is applied to calculate the vertical and lateral dynamic wheel–rail forces. A three-dimensional finite element model of the slab track system is then established in which the through-transverse crack at the bottom of concrete base is created by using extended finite element method (XFEM). The wheel–rail forces obtained by the vehicle-track dynamics calculation are utilized as the inputs to finite element model, and then the values of dynamic SIFs at the crack-tip are extracted from the XFEM solution by domain based interaction integral approach. The influences of subgrade modulus, crack length, crack angle, friction coefficient between cracked surfaces, and friction coefficient between faces of concrete base and subgrade on dynamic SIFs are investigated in detail. The analysis indicates that the subgrade modulus, crack length and crack angle have great effects on dynamic SIFs at the crack-tip, while both of the friction coefficients have negligible influences on variations of dynamic SIFs. Also the statistical characteristics of varying SIFs due to random wheel–rail forces are studied and results reveal that the distributions of dynamic SIFs follow an approximately Gaussian distribution with different mean values and standard deviations. The numerical results obtained are very useful in the maintenance of the slab track system.