梯式轨枕轨道模态试验分析

梯式轨枕轨道已成为控制地铁列车振动的有效措施之一,但枕下减振垫板的铺设形式如何影响梯式轨枕轨道的动力性能尚没有展开系统研究。该文通过多输入多输出模态测试方法,分析了枕下减振垫板的三种铺设方式对梯式轨枕轨道动力特性的影响。分析得出:现有的枕下减振垫板铺设方式,具有最小的一阶自振频率33Hz。单侧铺设10块枕下减振垫板的梯式轨枕轨道,具有最大的一阶阻尼比4.2%。三种枕下减振垫板铺设方式,梯式轨枕轨道前6阶阻尼比都具有先减小后增大的规律,一阶振型都沿轨道中心线对称。单侧铺设5块和7块枕下减振垫板的梯式轨枕轨道,二阶振型都沿轨道中心线反对称,和单侧铺设10块枕下减振垫板的梯式轨枕轨道正相反。分析结果为梯式轨枕轨道的工程应用提供了参考。     

纵向轨枕长度对梯式轨道减振性能的影响

为研究纵向轨枕长度对梯式轨道减振性能的影响,在现有纵向轨枕长度(6.15 m)的基础上,设计了另外两种纵向轨枕长度(3.65 m和8.65 m)。通过有限元软件Ls-Dyna建立不同纵向轨枕长度的梯式轨道模型,并通过实验室测试,验证其正确性。分析结果表明:纵向轨枕长度为6.15 m的梯式轨道(1)时域内,具有最小的基底振动加速度峰值;(2)1 Hz~200 Hz频段,具有最小的基底振动加速度峰值(峰值频率为49 Hz);(3)除1 Hz~5 Hz频段外,传递损失均大于纵向轨枕长度为3.65 m的梯式轨道传递损失。1.6 Hz~2.2 Hz频段以及7.6 Hz~200 Hz频段,传递损失大于纵向轨枕长度为8.65 m的梯式轨道传递损失。     

城市轨道交通梯形轨枕轨道高架桥梁试验研究

作为一种新型的减振轨道,梯形轨枕轨道已在国内的城市轨道交通中有所应用.该文介绍了在北京地铁五号线高架桥梯形轨枕轨道试验段进行的一系列现场试验,以及为验证其减振特性进行的室内试验.通过对轨道不平顺进行测量,并测试了当列车分别运行在梯形轨枕轨道和普通无碴板式轨道上时钢轨、轨枕和桥面的振动响应,该文对测试数据在时域和频域进行...     

地铁钢轨波磨对轨道结构振动及减振特性影响

现场调查某地铁线路上普通短轨枕、先锋扣件和钢弹簧浮置板三种轨道的钢轨波磨特征,并分别进行振动测试,研究钢轨存在波磨时,三种轨道结构的振动特性及减振效果。结果表明:三种轨道结构都是内轨波磨明显,外轨表面不平顺幅值相比内轨都很小,可以忽略不计其影响;波磨主波长频率成分很容易在轨道各零部件(包括隧道壁)振动中激发出来,并且会引起较大幅值的振动;在4 Hz~200 Hz频率范围内,波磨激励下的减振型轨道依然具有良好的减振性能,但是与其最初设计用于的减振效果相比,有明显的下降;先锋扣件轨道短波长波磨会削减隧道壁在高频段的减振效果;钢弹簧浮置板轨道的波磨幅值显著,虽然对其隧道壁的减振效果影响不明显,但是会造成钢轨振动增加。     

不平顺条件下高速铁路轨道振动的解析研究

为了分析不平顺条件下高速铁路轨道结构振动,推导了移动车辆在轮对处和轨道结构在轮轨接触点处的柔度矩阵,考虑移动轴荷载和轨道不平顺,建立了移动车辆-轨道垂向耦合振动的解析模型.模型中,移动车辆考虑为弹簧和阻尼器连接的多刚体系统;有碴轨道结构模拟为连续弹性3层梁;轮轨间考虑为线性赫兹接触.算例分析了单台TGV高速动车引起的有碴轨道结构振动,得到轨道不平顺引起的动态轮轨力和轨道各部分的最大振动加速度,研究了列车速度、轨道不平顺以及轨下垫板及扣件、道床和路基等轨下基础刚度对轨道振动的影响.计算表明:随着列车速度和轨道不平顺的增加,轨道结构的振动响应不断增大;轨下基础刚度对轨枕和道床的振动影响较大,对钢轨振动的影响较小.     

有砟轨道动力性能分析的频域方法

建立有砟轨道的三层连续弹性支承模型,推导了钢轨、轨枕和道床的运动方程,并在频域内求得简谐激励下的稳态响应。再引入轮轨相互作用频域模型,并借助动柔度法计算轮轨力。在此基础上,采用MATLAB平台自编程序,实现轨道不平顺激励下的频域分析。在案例分析中,综合考虑轮轨力、力传递率、轨道各部件的振动等指标,对弹性扣件、枕下弹性垫板、复合轨枕、道砟垫以及它们的组合等多种减振措施进行对比。结果表明：减振措施使得系统的固有频率发生改变,进而导致各指标在不同频率范围出现复杂的变化规律;相比于弹性扣件,枕下弹性垫板和道砟垫表现出更好的综合效果,而复合轨枕的减振效果有限。     

梯形轨枕轨道振动特性研究

为了探明梯形轨枕轨道在地铁车辆作用下的振动特性,利用车辆-轨道合动力学理论建立了地铁车辆和梯形轨枕轨道系统振动模型,假设车辆模型为多刚体系统,钢轨模型为无限长两端绞支离散支撑的Euler梁,用有限长两端自由的Euler梁模拟离散弹性支撑的梯形轨枕,利用显式积分法求解车辆-轨道非线性动力学方程,计算分析了梯形轨枕轨道在地铁车辆作用下的振动特性,讨论了轨道系统的振动与列车运行速度之间的相关性。研究结果表明:梯形轨道具有良好的减振性能,可以减小基础的动反力;随着地铁车辆速度的增加,钢轨和轨枕的垂向振动有所增大,而横向振动变化不明显。轮轨力随着车速的升高而增加。     

蚁群算法耦合LS-DYNA梯式轨枕轨道动力特性优化

为研究枕下减振垫材料密度和弹性模量对梯式轨枕轨道动力特性的影响,提出连续函数蚁群算法耦合LS-DYNA动力有限元程序的方法。首先利用连续函数蚁群算法程序,优化设计变量;其次,调用LS-DYNA动力有限元程序,对优化参数后的有限元模型进行计算;最后,将LS-DYNA动力有限元程序计算得到的结果反馈给连续函数蚁群算法程序。利用该方法,研究得出：在可取的材料参数范围之内,梯式轨枕轨道枕下减振垫最佳材料密度为620 kg/m3,最佳弹性模量为6.25×106 N/m2。将优化后的枕下减振垫用于地铁运营线,基底台座1 Hz~80 Hz频段加权VLz减小6.5 dB。因此认为,连续函数蚁群算法耦合LS-DYNA方法优化梯式轨枕轨道动力特性有效。     

两种新型材料地铁轨枕的降噪性能研究

利用基于有限元-边界元方法结合的轨道系统振动-声辐射模型研究采用树脂材料和不饱和聚酯材料制造两种新型材料地铁轨枕振动-声辐射特性。首先通过力锤敲击方法分别得到两种新型材料轨枕和传统混凝土轨枕结构阻尼系数。然后,用三维实体有限元模型模拟包含钢轨、轨下垫层、轨枕和道床的轨道结构,以单位力作为激励源,采用有限元法计算轨道结构系统响应。最后,以轨道结构位移响应作为输入,利用声学边界元法计算得到轨道结构声辐射。仿真结果表明,两种新型材料轨枕比传统混凝土轨枕都具有一定减振降噪效果。两种新型材料轨枕相比之下不饱和聚酯材料轨枕降噪效果要比树脂材料轨枕更显著。     

列车荷载作用下有砟轨道轨面沉降与路基不均匀沉降间的相关关系

有砟轨道路基发生不均匀沉降时,在列车荷载作用下,轨面会产生相应的沉降,进而影响列车运行的安全性和舒适度。在已有室内试验研究的基础上,采用二维颗粒流方法建立钢轨、轨枕和道砟的离散元模型,分析了路基不均匀沉降及列车荷载变化对轨面沉降的影响。结果表明：在路基不均匀沉降的波长一定时,随着波幅的增大,轨面沉降的波幅先逐渐增大而后稳定,并最终引起轨枕空吊;而轨面沉降的波长基本不受路基沉降波幅变化的影响,并且可按路基沉降波长以25°向上扩散至轨面进行简化计算;轨枕未出现空吊时,轨面沉降波长受列车轴重、动荷载大小及频率变化的影响很小,轨面沉降波幅受动荷载频率变化的影响很小,但受动荷载大小和轴重变化的影响显著。     

地铁隧道内不同轨道结构振动测试与分析

通过对地铁隧道内普通整体道床、Ⅲ型轨道减振器、弹性短轨枕、梯形轨枕、钢弹簧浮置板道床的现场振动测试,进行时、频域对比,了解各种减振措施在不同频率范围内的减振效果差异。结果表明,轨道减振器、梯形轨枕、弹性短轨枕及钢弹簧浮置板可分别降低隧道壁VLZmax分别为4 dB,7.6 dB,7.8 dB,19.0 dB;无论何种轨道减振措施,高频减振效果高于低频减振效果, Z计权的振动加速度级明显小于不计权的振动加速度级减振效果;梯形轨枕、弹性短轨枕、轨道减振器对50 Hz以上振动减振效果明显,钢弹簧浮置板道床对12.5 Hz以上振动减振效果明显,对控制列车运行产生的二次噪声更有效。     

高速铁路桥上有砟-无砟轨道过渡段动力学研究

基于京沪高速铁路特大桥上的有砟轨道与CRTS II型板式无砟轨道之间的过渡段实例,建立了车辆-轨道耦合动力学有限元计算模型,通过不同结构处理措施对有砟-无砟轨道过渡段动力学特性的影响研究,研究表明：当有砟轨道轨下胶垫刚度为55～75MN/m,无砟轨道轨下胶垫刚度为20～30MN/m时,有砟轨道的整体刚度大于无砟轨道;当有砟轨道轨下胶垫刚度为55～75MN/m,无砟轨道轨下胶垫刚度为40～50MN/m时,无砟轨道整体刚度与有砟轨道大体相当;过渡段枕、宽枕等不宜在有砟轨道刚度大于无砟轨道时使用;采用道砟胶结后提高了道床的整体性及过渡段轨道结构的稳定性,但增加了轨道刚度,应同时降低轨下胶垫刚度,以减小轮轨力;辅助轨只是增加了轨道结构的稳定性,对轨道刚度影响较小。     

In situ impact testing of a light-rail ballasted track with tyre-derived aggregate subballast layer

In this study, the dynamic behaviour of ballasted track with and without tyre-derived aggregate (TDA) as subballast layer was assessed using impulse–response (IR) test. For this purpose, a prototype of a ballasted track was established and many IR tests were carried out. The obtained results were represented in three different kinds of velocity–time, velocity–distance and velocity–frequency curves. Processing of the obtained results revealed that TDA efficiency in terms of vibration reduction was in the range of 17–46 dB when the impact was applied to the ballast and it was in the ranges of 6–32 dB and 6–47 dB while impact locations were on the sleeper and rail, respectively. Overall, it was proven that TDA with the particle size of 5–50 mm and thickness of 200 mm reduced by 6–47 dB in vertical vibrations with the dominant frequency range of 32–63 Hz.     

地铁列车振动对精密仪器影响的预测研究

以北京某新建地铁线路近距离经过某科研单位为研究背景,对现况道路边和实验室内仪器实验台面的环境振动进行了测试和评估;利用了现场实测与数值模拟相结合的预测方法,该方法考虑了建筑结构、实验台在不同频段下的振动衰减或放大作用,并在1/3倍频程频域下与国际通用的精密仪器防振要求进行比较。采用周期性有限元-边界元耦合方法预测了列车对自由场地的动力响应。基于实测振动响应传递比曲线将楼外振动响应折算到实验台面上,以此评价地铁列车振动对精密仪器的影响。研究结果表明：1）现况道路车流对实验台水平方向振动较大,应采取相应被动隔振措施;2）当列车低速、匀速通过时,振动对仪器影响较小;3）车速大于60km/h匀速通过时,应采用较高级别的减振轨道以确保仪器正常工作。     

Effect of sand-fouled ballast on train-induced vibration

One of the most important issues in desert areas is ballast layer solidification due to windy sand accumulation. This phenomenon increases track modulus which leads to serious damage in railway track components. On the other hand, one of the side effects of this problem is the increase in ground-borne vibration during train passing. Therefore, this research is devoted to the investigating effect of sand-fouled ballast on train-induced vibration by means of experimental and numerical methods. For this purpose, five sections of ballasted railway track in central desert of Iran were monitored for 6 months, and many field measurements were conducted for obtaining track stiffness and ballast fouling percentage. Then, the field measured track stiffness values were implemented in finite element model, and the environmental vibrations due to train passing were assessed in the form of acceleration and displacement time histories for adjacent points of the railway track. The results indicated that, due to the increase in ballast fouling percentage from 0 to 62.7%, maximum acceleration increased by approximately 43% and maximum displacement decreased by approximately 68%.     

轨道减振器与弹性支承块或浮置板轨道组合的隔振性能分析

轨道交通运行引起的地面振动或高架轨道的高架桥结构振动源于轨道结构振动，对于几十赫兹到几百赫兹频率范围的轨道结构振动，应用轨道减振器、弹性支承块和浮置板可以得到比较好的减振降噪效果。本文在频域建立了轨道结构模型和车辆一轨道系统相对位移激励模型，分析计算了钢轨垫片／轨道减振器一弹性支承块／浮置板轨道结构的隔振性能，以及相对位移激励下轮轨间动载荷和传递给基础的力。结果表明，与垫片一弹性支承块／浮置板轨道相比，轨道减振器一弹性支承块／浮置板轨道组合可以在中频范围大大降低轮轨动态作用力，并且在中、高频段具有更好的隔振性能。     

Prediction of displacement induced by tilting trains running on ballasted tracks through measurement of track impact factors

In the track design and behavior prediction, the variable contribution of wheel load was evaluated by considering the design load for the tracks. Further, the track impact factor was used to calculate the dynamic wheel load as a single value, which was chosen according to the rail type (i.e., continuous welded rail or joint rail) and the design speed but did not take into consideration the track conditions (i.e., the ballast condition good or bad), train type (i.e., tilting train and EMU), and track components (i.e., sleeper type and fastening type). In this study, the measured track impact factor was applied to the time history function of the FE analysis in order to predict the displacement of ballasted tracks under real conditions, which included curved and the deteriorated tracks, thus increasing the train speed by approximately 20–30% of the existing train speed. Therefore, the dynamic wheel load and the rail and sleeper displacement were measured for two different trains running on four conventional curved track sections with two different sleeper types. The track impact factor was estimated from the measured dynamic wheel load, and the empirical dynamic wheel load was calculated using the measured track impact factor at each site. The measured track impact factors were used for simulating the dynamic wheel loads applied on the derived time history function for fast trains. A finite element analysis model using the derived time history function based on the empirical dynamic wheel load was used to predict the train-induced track displacement. The numerical simulations and field test results were compared with German and Japanese regulations for train-induced track displacement, and the speedup effect of a tilting train was compared with that of a general train (EMU).The empirical track impact factors were 17–18% higher in the R400 sections than in the R600 sections. As the track curvature decreased, the impact on the track increased. Therefore, the empirical track impact factors were 21–23% higher in the WT sections than in the PCT sections. At 70 km/h, the impact on the track from a tilting train was 7–11% less than that from EMU. Although the tilting train sped up by 30% (90 km/h), its response level was similar to or less than that of the EMU. The analytical results reproduced the experimental results well within about 2–5% difference in the values. Therefore, the derived time history function based on the measured track impact factors is considered to provide sufficiently reliable FEA results in the investigation of the behavior of ballasted tracks. The difference between the maximum displacements for both train types on all the sections was about 15–20%.The analytical results show that the speed limits of the tilting train were higher than those of the EMU by approximately 8–23 km/h at each test site. Therefore, the speed limit of each test site was estimated by considering the limit of sleeper displacement. It was shown that the time history function derived using the measured track impact factor on a small track curvature with wooden sleepers was higher than that in other test sections. Therefore, it would be advantageous to increase the weight of sleepers on existing lines to increase the train speed through the speedup effect without increasing the track curvature. The increase in the speed of a tilting train with a small track curvature was much better than that by a track curvature increased by approximately 10%.     

铁路卧铺客车人体振动舒适性建模与仿真

铁路卧铺客车乘客在卧姿状态下所承受的全身振动是影响其乘用舒适度的主要因素。研究了卧姿人体垂直振动模型,在铁道车辆二系悬挂动力学模型基础上,考虑卧铺的隔振作用与卧姿人体的垂直振动响应特性,建立了14自由度"人-铺-车辆"振动系统空间垂向耦合动力学模型,研究了在轨道随机不平顺激励下的卧姿人体垂直振动响应。应用卧姿人体全身振动舒适性评价标准,建立了铁路卧铺客车人体振动舒适性仿真流程。通过对人体头-臀二部位加速度均方根值先后进行部位计权和频率计权,得到卧铺客车卧姿人体振动舒适性指标。以M atlab为工具编制了卧铺客车人体振动舒适性仿真软件,交互输入车辆与人体的结构和动力学参数后,自动完成卧姿人体振动舒适性仿真计算,进而为铁路卧铺客车人体振动舒适性分析及车辆悬架参数优化提供了有效分析手段。