Train-induced vibration on elevated railway station

Results of in-situ vibration measurement carried out at Tianjin West Elevated Railway Station which has the trains running on the station structure were reported. The main excitation source is the train passing through the station. Vibration measurements were recorded in the vertical direction of the supporting track beam, the platform and the steel truss beam of the waiting hall, as well as in the vertical, longitudinal and transverse directions of the roof arch base of the station. Acceleration time responses were obtained. The maximum value, vibration level and one-third octave band RMS spectra of the measured accelerations were studied. The propagation of vibration in different structural floors was discussed. The influence of train speed, distance to the vibration source and the type of train on the structural vibration were analyzed. Results show that the vibration level increases with the train speed, while it attenuates with the distance to the track. Furthermore, the vibration responses of different structural floors were compared, and it is noted that the vertical vibration of the bottom slab of the platform is most severe and the transverse vibration of the roof arch base is the smallest. The results provide reference on the vibration characteristics and vibration energy distribution of this type of "Train on building frame" system used as an elevated railway station.

Dynamic response analysis of train-induced vibration impact on the Probhutaratna pagoda in Beijing

Train-induced vibration exhibits a potential dynamic impact on historic buildings and especially on those with high historical and cultural value.Under the long-term reciprocating load of train vibrations,structural fatigue damage can occur,and thus,a significant problem involves effectively evaluating and mitigating vibration impact on historic buildings while developing a rail transit system.In the present study,train-induced vibration impact and dynamic behavior of Probhutaratna pagoda in the suburb of Beijing,which has a history of approximately 1000 years,was investigated.To examine the dynamic behavior of the Probhutaratna pagoda and determine the weakest position in its architectural damage under train loads,its dynamic characteristics were measured.The free vibration modes were identified based on the dynamic measurement results.Subsequently,a finite element(FE)model of the Probhutaratna pagoda was constructed and the models and train-induced structural responses were compared with measured results.Finally,the structural dynamic responses to moving train loads were analyzed in detail.The results indicate the following conclusions.(1)The dominant frequency of the ambient vibration is below 4 Hz,and the dominant frequency of the train-induced vibration is between 8 and 16 Hz.(2)The first,second,and third order natural frequencies are 1,3.25,and 6 Hz,respectively,in the west-east direction,and are 1,3.25,and 6.25 Hz,respectively,in the north-south direction.(3)The two weakest locations(A and B)of the Probhutaratna pagoda are observed at the spire bottom and west gate of the first floor.At location A,the maximum principal stress reached 243.6 N/m^2 and the corresponding maximum tensile strain reached 3.74×10^-7.

Investigation into the Vibration of Metro Bogies Induced by Rail Corrugation

The current research of rail corrugation mainly focuses on the mechanisms of its formation and development. Compared with the root causes and development mechanisms, the wheel-rail impacts, the fatigue failure of vehicle-track parts, and the loss of ride comfort due to rail corrugation should also be taken into account. However, the influences of rail corrugation on vehicle and track vibration, and failure of vehicle and track structural parts are barely discussed in the literature. This paper presents an experimental and numerical investigation of the structural vibration of metro bogies caused by rail corrugation. Extensive experiments are conducted to investigate the effects of short-pitch rail corrugation on the vibration accelerations of metro bogies. A dynamic model of a metro vehicle coupled with a concrete track is established to study the influence of rail corrugation on the structural vibration of metro bogies. The field test results indicate that the short-pitch rail corrugation generates strong vibrations on the axle-boxes and the bogie frames, therefore, accelerates the fatigue failure of the bogie components. The numerical results show that short-pitch rail corrugation may largely reduce the fatigue life of the coil spring, and improving the damping value of the primary vertical dampers is likely to reduce the strong vibration induced by short-pitch rail corrugation. This research systematically studies the effect of rail corrugation on the vibration of metro bogies and proposes some remedies for mitigating strong vibrations of metro bogies and reducing the incidence of failure in primary coil springs, which would be helpful in developing new metro bogies and track maintenance procedures.

Field measurement and evaluation of vibration in different areas of a metro depot

This paper presents a study of the characteristics of a railway vibration at three key sections containing different track structures in a metro depot.The results show that the vertical and horizontal vibration acceleration levels are proportional to train speed.The Z-weighted vertical acceleration levels obtained showed that the vibration source strengths at the ballast foot of the testing line and the throat area were very close.The vibration attenuation at the repair line was larger than that of the testing line.In the throat area,the peak frequency of vibration obtained at the ballast foot(2.5 m)could be shifted to a lower frequency band by using polyurethane sleepers instead of standard concrete sleepers.Polyurethane sleepers can help to reduce vertical vibration in a frequency band of 0-10 Hz.The vibration levels would satisfy the limits given in the ISO2631-2-2003(2013)for any location more than 5 m away from the source at the testing line and 2.5 m away from the source at the repair line and throat area.

Field monitoring of railroad embankment vibration responses in seasonally frozen regions

To investigate the vibration characteristics of a railway subgrade in different seasons, three field experiments were carried out in the seasonally frozen Daqing area of China during spring, smnmer, and winter. The vibration characteristics and attenuation rates of the subgrade induced by passing trains were investigated, and the influences of the season, train speed, train type, train load, and number of train compartments are described in this paper. The results show that： （1） near the rail track the vibration in the vertical direction was more significant than in the lateral and longitudinal directions, and as the distance from the railway track increased, the acceleration amplitudes and the attenuation rates all decreased in all three directions; （2） the acceleration amplitudes and at- tenuation rates decreased in the three different study seasons as the distance from the railway track increased, and the attenuation rates in the freezing period were the largest; and （3） the acceleration amplitude induced by a freight train was greater than that by a passenger train, and the subgrade vibration increased with increasing passenger train speeds when the number of train compart- ments was similar. These results have great significance for enhanced understanding of the characteristics of wain-induced vibra- tion embankment response in seasonally frozen regions, and provide essential field monitoring data on train-induced vibrations in order to improve the performance criteria of railroading in seasonally frozen regions.

基于评价指标转换法的地铁环境振动烦恼度研究

为研究地铁环境振动水平与人体主观烦恼度感受之间的关系,采用指标换算法,推导了最大Z振级VL_(z, max)与四次方剂量值(vibration dose value, VDV)之间的转换关系,并通过现场测试对转换公式中的待定系数进行了拟合。借鉴基于VDV指标的暴露-响应关系研究成果,得到了基于VL_(z, max)指标的暴露-响应曲线,初步实现了基于我国国标推荐指标的居民振动烦恼度评价。研究表明:单位时间内过车数目增多会导致人体产生烦恼度的比例增加;国标GB 10070、GB/T 50355和GB 55016中推荐的振动限值所对应的居民烦恼度,与国外标准中限值所对应的烦恼度基本一致,最严格限值对应的高度烦恼度比例约为3%。

公铁合建双层盾构隧道设计关键技术

为解决公铁合建双层盾构隧道面临的总体布置、结构设计、汽车与地铁车辆联合振动以及通风排烟等技术难题,以武汉长江公铁隧道和济南黄河济泺路隧道工程实践为基础,采用方案综合比选、2.5维数值计算等方法,对公铁合建双层盾构隧道设计关键技术进行系统研究。结果表明:1)通过对隧道平面、纵断面和横断面的合理优化布置,并在废水泵房段、疏散楼梯段采取特殊布置方案,可减少公铁合建盾构隧道地下空间占用,并提高断面利用率,减小盾构隧道外径;2)采用半预制半现浇的管片+非封闭内衬结构型式,能充分发挥内部结构与管片衬砌的联合承载作用,显著减小河床冲淤作用;3)汽车与地铁联合振动作用对隧道影响较小,隧道基底饱和粉细砂地层不会发生液化;4)地铁隧道采用分段纵向烟道,可解决地铁长大区间无风井条件下的排烟难题,同时提高疏散便捷性,并大幅降低建设难度;5)公铁合建隧道在运营管理上不可避免地会出现交叉和影响,建议在管理界面划分和投资分劈上提前研究,便于决策。

地铁钢轨波磨对车辆-轨道振动及噪声特性的影响

钢轨波磨作为地铁线路中最为常见的轨道损伤问题之一,始终未得到根本性的解决。为研究不同轨道结构形式产生钢轨波磨后车辆内部振动噪声以及轨道结构振动的时频域特性,探究钢轨波磨对车辆和轨道的影响,对某地铁线路进行现场动静态测试,获取了钢轨波磨激励下车辆内部的振动和噪声响应以及轨道各部件的振动响应,使用时域指标统计、1/3倍频程谱分析等方法分析轨道振动响应特征和车内振动及噪声响应特征。结果表明:在小半径曲线地段,浮置板轨道产生了特征波长约为200 mm的钢轨波磨,整体道床轨道产生了特征波长约为60 mm的钢轨波磨;浮置板轨道的钢轨、道床板、隧道壁振动加速度有效值分别是整体道床的1.8、5.8倍及0.3倍;钢轨波磨对轨道振动的影响主要体现在中高频范围,在300~400 Hz附近,浮置板轨道振级从钢轨至隧道壁共衰减66 d B,而整体道床共衰减49 d B;列车通过测试区域时,转向架上方与客室中部垂、纵向振动加速度有效值基本一致,而客室中部横向振动加速度有效值约为转向架上方的2倍;车内转向架位置处的异常振动主要来源于钢轨波磨的激励,且短波长波磨所激励的车内振动及噪声更加剧烈。因此,地铁钢轨波磨产生后在轨道及车辆的振动噪声响应中均占主要成分,应及时对钢轨进行打磨处理,研究结果可为地铁工务维修提供理论指导。

地铁曲线波磨地段振动特性影响因素分析

为研究地铁曲线波磨地段振动特性影响因素,建立车辆-轨道及轨道-隧道-大地模型,分析不同波磨波深、隧道埋深、轨道减振措施下隧道壁及地面的振动响应。结果表明:减小钢轨波磨波深或增加隧道埋深,隧道壁和地面的垂向最大加速度和加速度分频最大振级均有减小趋势;采取不同轨道减振措施时,浮置板的减振效果最佳;隧道埋深和轨道减振措施的改变,不会改变隧道壁和地面加速度峰值的频段区间及加速度分频最大振级的中心频率;振动在隧道壁传递到地面的过程中高频衰减较快。

地铁上盖建筑振动响应预测及舒适度分析——以南京地铁1号线停车维修库综合体上盖住宅项目为例

对南京市地铁1号线车库段上部待建住宅楼进行研究,探讨地铁上盖建筑受地铁出入库振动的影响。通过现场测试与数值模拟,预测不同工况下待建建筑的振动响应以及室内振动加速度限值范围。模拟结果表明,采用底部加速度法将所测轨道、混凝土柱的振动输入计算模型中,可以获得待建建筑三向位移变化,并进行结构易损部位及预警分析,判断建筑安全性。通过模拟8种工况,计算得到1~80 Hz频率范围内各建筑楼板1/3倍频程中心频率下的加速度响应有效值和加速度振级,获取了住宅舒适度影响较大区域的具体坐标。研究成果对结构减振及舒适度提升具有参考意义。

地铁盾构下穿古建筑振动监测与保护研究

为确保地铁盾构下穿古建筑物施工安全,确定先评估、先加固、施工监测、后评估、后加固总体技术路线。通过建立古建筑1︰3.52的实体模型并进行振动台试验获取结构阻尼比,利用Ansys进行三维建模,采用结构与模态分析,针对易损结构进行加固预防,为后续振动监测与盾构施工提供参考依据,结合试验区施工监测数据,调整施工参数。结果表明:在静力分析下该结构位移最大值约为14.01 mm,验证了三维模型的有效性。通过模态分析确定结构模型基本频率为0.59046 Hz,最易受损位置为斗枋处。在盾构穿越过程中,古建筑物加速度变化幅度小于0.003 m/s2,振动频带主要集中在0.6~20.5 Hz,振动频带处于正常范围,对古建筑物基本无影响。针对盾构下穿古建筑物提出以“地铁盾构穿越以匀速掘进为主,避免运营高峰期作业,影响区地层之间使用注浆加固,对古建筑物易损结构进行支护,施工时采取隔振减振方案”的总体解决思路,为后续类似工程建设提供参考。

国内首座“架空+上盖开发”大架修基地设计创新

研究目的:“架空+上盖开发”的大架修车辆基地综合开发空间形态在国内没有先例,需要解决车辆基地建设对城市土地和空间的割裂、地面层空间利用、提高盖上物业开发强度、减振降噪、设备基础和管线敷设等技术难题。本文通过国内首座“架空+上盖开发”大架修车辆基地设计实践,提出解决以上技术难题的工程方案,供业内同行参考借鉴。研究结论:(1)架空方案能够有效减轻车辆基地建设对城市土地和空间的割裂;(2)通过盖上物业核心筒结构落地,将上盖物业车库置换到地面层,可高效利用地面层空间,提高物业开发强度和收益;(3)在咽喉区、库内检查坑及库外线路大面积采用橡胶弹簧浮置板减振道床等措施可以较好地解决车辆基地振动噪声问题;(4)利用架空板下沉和地面层局部空间,可以解决设备基础和管线敷设难题;(5)本研究成果提出的思路和方法对类似工程建设有参考和借鉴价值。

公轨合建盾构隧道振动荷载的动力响应特性

为了探究汽车-列车振动荷载对公轨合建盾构隧道内部结构及周围土体的动力响应特性,采用有限元软件ABAQUS对某公轨合建盾构隧道内部结构及周围土体进行数值模拟,通过ABAQUS软件的Dload子程序对汽车、列车振动荷载进行耦合,分别将单一振动荷载及汽车-列车振动荷载作用引入公轨合建盾构隧道,分析公轨合建盾构隧道内部结构及周围土体在不同工况时加速度、位移、应力、应变的变化。结果表明:汽车、列车振动荷载频率不同,共同作用后产生拍频现象,导致相同方向合成荷载的振幅可能小于分荷载的振幅,当频率相同时所合成荷载的振幅最大;管片上方的土体以及非封闭弧形内衬外侧土体发生较大的应变,最大塑性应变发生于拱顶偏右侧,达到7.032×10^(-6);公轨合建盾构隧道内部结构中的预制箱涵牛腿柱、顶板处出现较大拉、压应变,在长期运营期间需要对预制箱涵牛腿柱、顶板位置进行定期检查和必要支护。

钢弹簧浮置板轨道减振性能现场对比测试

为研究随机列车荷载作用下钢弹簧浮置板轨道(steel spring floating slab track,简称SSFST)上线运营后的减振效果,选取某地铁线路同一区间、同一曲线段内的普通无砟轨道及钢弹簧浮置板轨道典型测试断面,在同一天内开展了现场对比测试。研究结果表明:钢弹簧浮置板轨道减振效果的线上评估结果与列车、轨道的实际运营状态直接相关;在不同列车的随机激励作用下,Z振级相对插入损失(ΔVL_(Z,max))相差超过10 dB,且部分测试样本无法满足特殊减振的设计需求;为获得保守的评价结果,应选择轮、轨平顺状态良好的运营区段开展对比测试;通过合理的养护维修,使运营列车及轨道保持良好的运行状态,是减振轨道区段满足振动控制需求的关键。

地铁线路邻近建筑物室内振动烦恼率预测分析

为实现地铁线路邻近建筑物室内振动舒适度定量计算,提出场地振动响应数值模拟与链式衰减公式相结合的预测的方法,得到不同类型建筑物室内振动响应。首先,以预测振级为自变量,采用正态分布函数描述人对振动感觉的随机性,建立地铁线路邻近建筑物室内振动烦恼率模型;其次,以石家庄地铁为例,建立了场地振动预测模型,借助链式衰减公式,得到不同类型建筑物的室内振动烦恼率分布规律。研究结果表明:建立的烦恼率模型变异系数取0.15时,均方根误差为0.086,模型预测精度满足要求;在设计工况下给出了各类建筑物在不同区域的达标距离,对于0类区域,Ⅰ~Ⅴ类建筑物达标距离分别为12,14,20,44和46 m,对于5类区域任意距离都达标。该研究成果可为烦恼率评价法在地铁沿线建筑物振动舒适度预测和评估应用提供参考。

地铁车辆构架异常振动及疲劳失效

[目的]随着地铁运营里程及线路条件复杂性的增加,由轮轨磨耗引起的转向架异常振动时有发生,转向架构架作为重要承载部件,需要对其在异常振动条件下的结构完整性与振动失效机理进行研究。[方法]以某地铁转向架为例,基于转向架振动传递测试和动应力数据,开展某线路地铁车辆在运营过程中构架出现的异常振动及横梁疲劳失效原因研究,分析激扰来源和振动传递路径。基于构架运营模态测试结果,分析车辆在通过典型路段时的振动加速度及横梁失效点的动应力时频特征。通过分析车轮多边形、钢轨波磨、车辆运行速度等因素,研究构架横梁动应力的幅值及其频谱特征。[结果及结论]车轮镟修前,等效应力幅值的主要超限测点集中在横梁和侧梁连接处、横梁和小纵梁连接处及横梁上部分线缆支座处;车轮镟修后,全部测点的等效应力幅值均显著降低,远小于许用应力幅值。导致构架横梁开裂的主要外部激励源为5~8阶车轮不圆,车轮不圆引起的车辆振动加剧是构架横梁线缆支座疲劳失效的直接原因。

嵌入式轨道系统振动传递研究

[目的]嵌入式轨道的阻尼较大,有较好的减振降噪性能,因此有必要对嵌入式轨道的减振降噪机理进行研究。[方法]以广州地铁14号线为例,对嵌入式轨道系统与普通扣件式轨道系统进行了静态与动态的振动测试;基于现场测试的轨道结构频响函数及纵向衰减率,分析嵌入式轨道系统的减振特性。[结果及结论]嵌入式轨道系统在垂向减振中存在着明显的工作频段;嵌入式轨道在绝大多数频段中的振动加速度幅值均小于普通扣件式轨道的振动加速度幅值;当振动频率为550~1200 Hz时,嵌入式轨道的高分子阻尼材料与弹性垫板的减振体系在该频段具有良好的吸振能力;嵌入式轨道与调频式钢轨阻尼器一样存在固定的调整频段,其调整频带范围在振动频率为400 Hz附近;相比于离散支承的轨道结构形式,连续支承的轨道结构形式在振动频率大于750 Hz频段的钢轨振动衰减率更优。

车辆段不同区域上盖建筑振动测试分析

为研究地铁列车在车辆段不同区域引起的上盖建筑振动问题,对广州某车辆段试车线,咽喉区及其上盖建筑进行现场振动测试,分析车辆段各区域车致振动特性及传递规律。分析结果表明,轨旁源强振动的主频随车速增加而增大,咽喉区15 km/h、试车线40和60 km/h工况的主频分别为31.5、40和50 Hz,试车线源强的振动能量要大于咽喉区。由于梁和楼板的阻抗作用,振动总能量在向上传播的过程中逐渐衰减,不同传递路径对不同频段振动的衰减作用不尽相同。建筑物内振动主频主要受楼板固有频率影响较大,主要集中在40~50 Hz范围。

地铁运行引起的环境振动变化规律及其主要成因分析

为分析地铁运行引起的环境振动变化特征及其主要成因,对北京某地铁沿线地表振动、隧道壁源强展开现场测试,统计全天所有列车的振动样本数据,对比分析不同车次、不同断面的振动变化规律,总结引起环境振动值离散变化的主要原因。结果表明:(1)列车通过时地表测点的振级差异最大可达到14.6 dB,离散程度大,虽然所采集20趟车的振级平均值满足了标准限值要求,但仍有30%~50%的振动值超过了标准限值;(2)隧道壁源强的差异达到22.1 dB,其原因为当天所有列车中存在5辆车的车辆状态存在异常,主要表现为车轮不圆顺,引起的隧道壁最大Z振级平均值达到了90.6 dB;(3)同一列车通过不同断面时,隧道壁振级变化显著,且与车辆状态存在显著关联,当车轮存在显著不圆顺时,不同断面的隧道壁振级差变化更为显著,最大可达到10.7 dB,是“普通车辆”的2倍,表明车轮及轨道状态的变化进一步改变了轮轨耦合作用,加剧了地铁运行引起的环境振动水平;(4)对“异常车辆”的进行车轮镟修后,地表的振动水平得到了有效降低,振级均降到了70 dB以下。

地铁车辆以磨耗车轮通过钢弹簧浮置板轨道时的较好平稳性速度

[目的]为使地铁乘客获得较好的乘车体验,探究轨道线路铺设浮置板时车体平稳性较好的通过速度区间。[方法]利用仿真软件建立了地铁车辆-浮置板轨道-路基的动力学模型,分析了标准车轮及磨耗车轮通过地铁有无钢弹簧浮置板轨道时的车体振动状况。对比了不同速度条件下,增设浮置板前后车体垂向平稳性指标时域及频域的变化;对比了车体在浮置板轨道系统下,车体以磨耗车轮与标准车轮通过时,车体的垂向振动加速度等参数时域及频域的变化规律。[结果及结论]不同速度时,浮置板会使列车的平稳性指标增大,相比无浮置板时平均增长了5.8%;横向平稳性指标在速度低于60 km/h时,其对平稳性指标有减小作用。浮置板系统中,磨耗车轮的存在会加剧车体垂向振动,这种现象在列车高速行驶时表现更突出。地铁车辆通过轨道时的垂向振动加速度频率主要集中在低频区段的0~10 Hz,横向振动加速度频率区段主要集中在0~30 Hz。地铁车辆通过存在浮置板路段且速度在48~60 km/h区间时,磨耗车轮的车体垂向平稳性指标在1.8左右,横向平稳性指标在1.1左右,数值均较低,即车体振动及横向运动较小,平稳性较好。