轨道不平顺引起的车轨桥空间耦合振动分析

轨道不平顺对车轨桥空间耦合振动的影响是一个有待研究的问题。本文建立了车辆一无碴轨道-桥梁系统的空间耦合振动模型,并通过功率谱密度得到轨道不平顺的时域模拟样本,以其为激励源,分析车辆-轨道-桥梁空间耦合振动响应。通过对比,考虑高低不平顺的空间模型与4种几何不平顺的计算结果,由此得到,轨道不平顺的改变主要影响轨上部分的振动,对轨下部分以及桥梁结构影响不大。     

车轨桥振动系统垂向模型和空间模型的比较

分别建立了车辆-轨道-桥梁系统的垂向耦合振动模型和空间耦合振动模型,并通过功率普密度得到轨道高低不平顺的时域模拟样本,以其作为激励,分析两种模型下车辆-轨道-桥梁耦合振动系统的振动响应。通过对比相同轨道高低不平顺激励下垂向振动模型和空间振动模型的垂向振动响应计算结果,分析了两种模型的优缺点和适用性。     

连续梁桥上CRTS双块式无砟轨道疲劳特性

为探讨梁轨非线性互制作用下连续梁桥上双块式无砟轨道系统静动力荷载下结构响应,预测桥上无砟轨道结构的疲劳寿命,基于梁轨相互作用原理与车辆-轨道-桥梁耦合动力学原理,以昌景黄铁路某(40+64+40)m连续梁为研究对象,采用有限元方法建立了考虑桥梁、支座、底座板、道床板、扣件和钢轨等构件及结构层间非线性约束的连续梁-CRTS双块式无砟轨道的一体化空间分析模型,研究列车静活载作用下桥梁、道床板、底座板及钢轨的动力响应特性与无缝线路纵向力分布规律,分析连续梁桥上无砟轨道结构疲劳特性。结果表明：温度荷载作用下钢轨最大压应力位于连续梁两端,最大拉应力位于桥梁跨中;竖向荷载作用下钢轨最大拉应力位于连续梁桥墩,最大压应力位于桥梁跨中;制动荷载作用下钢轨拉、压应力极值均位于桥梁桥墩;钢轨纵向力由温度荷载控制,最大应力为143.1 MPa,满足规范要求;列车动载作用下,简支梁和连续梁上钢轨最大拉、压应力相当,道床板最大拉应力出现在连续梁跨中限位凹槽附近,其板底拉应力大于板顶,底座板最大拉应力出现在连续梁主墩附近,且板顶和板底的拉、压应力基本相同;列车动载作用下,钢轨最易破坏处寿命约27.1 a,道床板和底...     

Effect of temperature difference load of 32 m simply supported box beam bridge on track vertical irregularity

In order to study the effect of temperature difference load (TDL) along the vertical direction of a simply supported beam bridge section on the vertical irregularity, a rail-bridge-piers calculation model was established. Taking 32 m simply supported box beam bridge which is widely used in the construction of passenger dedicated line in China as an example, influences of the temperature variation between the bottom and top of the bridge, temperature curve index, type of temperature gradient, and beam height on track vertical irregularity were analyzed with the model. The results show that TDL has more effects on long wave track irregularity than on short one, and the wavelength mainly affected is approximately equal to the beam span. The amplitude of irregularity caused by TDL is largely affected by the temperature variation, temperature curve index, and type of temperature gradient, so it is necessary to monitor the temperature distribution of bridges in different regions to provide accurate calculation parameters. In order to avoid the irregularity exceeding the limit values, the height of 32, 48, and 64 m simply supported box beam bridges must not be less than 2.15, 3.2, and 4.05 m, respectively.

     

高速列车随机激振载荷无砟轨道路基的动应力分布规律

相较于传统的列车轨道路基整体耦合三维有限元模型，提出一种优化处理列车荷载的方法，基于多体系统动力学理论建立列车轨道垂向耦合模型，并通过数值计算得到考虑了轨道随机不平顺条件下的轮轨激振载荷，随后利用二次开发子程序将轮轨载荷导入无砟轨道路基天然地基土非线性数值分析三维有限元模型，在此基础上研究分析高速移动荷载作用下路基的动应力分布规律。研究结果表明：采用的车辆荷载处理方法在保证计算精度的前提下代替车辆不平顺轨道路基地基整体耦合振动模型，降低了建模及计算时间成本；竖向动应力沿横向分布规律，在轨道结构中数值较大，路基基床内远小于轨道结构中的数值，基床表层及基床底层底面出现"马鞍形"分布；沿竖向分布，随着深度的增加，竖向动应力逐渐减小，在基床表层内的衰减率较大，甚至超过50%；沿纵向分布，在各结构层内产生了与转向架数目相等的应力峰值数目，列车运行过程中轨道及路基动应力的变化可以看作是反复的加、卸载过程；列车移动速度对路基动力响应影响作用明显，时速由200 km/h增长到350 km/h时，各结构层动应力幅值增长均超过30%。     

Vertical dynamic response of the ballastless track on long-span plate-truss cable-stayed bridges

An analytical model is presented to study vertical dynamic response of the ballastless track on long-span plate-truss cable-stayed bridges based on an explicit dynamic analysis method.In the model,the train,ballastless track and bridge are treated as a coupled vibration system with interaction.By simulating the dynamic process of the system,this paper discusses the distribution law of dynamic responses of the bridge deck and the bed slab.It shows the necessity of a base plate for the ballastless track on the long-span plate-truss cable-stayed bridge.Comparison of the influence of different train speeds and stiffness of the elastic vibration-damping pad on the dynamic responses of the bridge deck and the bed slab is also made.The reasonable stiffness value of elastic vibration-damping pad is proposed.     

基于傅立叶变换法的高速铁路轨道振动分析

建立轨道结构三层弹性梁模型,考虑轨道不平顺对振动响应的影响,利用傅立叶变换法求解振动位移.通过计算我国现有几种高速动车组运行时引发轨道结构的振动位移响应,得到轨道结构的振动加速度,分析了轨道不平顺及列车速度对振动幅值的影响.研究表明,较差的轨道不平顺状态及列车高速运行的组合情况下,轨道振动响应幅值将迅速增大.     

Beam-track interaction of high-speed railway bridge with ballast track

Based on the construction bridge of Xiamen-Shenzhen high-speed railway (9–32 m simply-supported beam + 6×32 m continuous beam), the pier-beam-track finite element model, where the continuous beam of the ballast track and simply-supported beam are combined with each other, was established. The laws of the track stress, the pier longitudinal stress and the beam-track relative displacement were analyzed. The results show that reducing the longitudinal resistance can effectively reduce the track stress and the pier stress of the continuous beam, and increase the beam-track relative displacement. Increasing the rigid pier stiffness of continuous beam can reduce the track braking stress, increase the pier longitudinal stress and reduce the beam-track relative displacement. Increasing the rigid pier stiffness of simply-supported beam can reduce the track braking stress, the rigid pier longitudinal stress and the beam-track relative displacement.     

钢丝绳卷扬垂直升船机设计的动力学问题探讨

分析了船只进出承船厢过程中的水动力学问题和防撞梁的碰撞动力学问题 ,提出用非线性浅水波方程建立水动力学模型 ,并考虑水体、船只和船厢之间的摩擦阻力 ,同时要考虑无粘无旋假设将引起的误差 ;分析了缓冲油缸和塑性简支梁两种防撞梁设计方案和相应的动力学问题 .分析了承船厢升降状态的动力学问题 ,主提升机系统的动力学建模要考虑机械传动间隙、制造安装误差 ,提出了采用MATLAB提供的SIMULINK模拟主拖动系统 ,并与主提升系统和钢丝绳承船厢子系统联结成整体模型 ,从而分析电气参数对动态性能的影响的方法     

轨道结构动力响应Newmark方法时间积分步长的确定

为了明确轨道结构动力响应计算中Newmark方法时间积分步长的确定依据,采用双层离散点支承轨道结构模型解析求解不同移动速度点荷载作用下的轨枕动反力频谱,进而采用模态叠加法和Newmark方法求解不同时间积分步长下上述双层轨道结构的位移和加速度响应,并与高精度的四阶Runge-Kutta方法计算结果对比.结果表明,不同荷载移动速度下的时间积分步长均应满足Nyquist采样定理,且采样定理中的频带宽度应至少包括由离散支承参数激励引起的轨枕动反力频谱的前二阶谷值.作为算例,根据上述采样定理确定的时间积分步长,采用Newmark方法计算了移动列车轴荷载作用下三层离散点支承轨道的枕木及道砟加速度响应.     

Effects of fundamental factors on coupled vibration of wind-rail vehicle-bridge system for long-span cable-stayed bridge

In a wind-vehicle-bridge(WVB) system,there are various interactions among wind,vehicle and bridge.The mechanism for coupling vibration of wind-vehicle-bridge systems is explored to demonstrate the effects of fundamental factors,such as mean wind,fluctuating wind,buffeting,rail irregularities,light rail vehicle vibration and bridge stiffness.A long cable-stayed bridge which carries light rail traffic is regarded as a numerical example.Firstly,a finite element model is built for the long cable-stayed bridge.The deck can generally be idealized as three-dimensional spine beam while cables are modeled as truss elements.Vehicles are modeled as mass-spring-damper systems.Rail irregularities and wind fluctuation are simulated in time domain by spectrum representation method.Then,aerodynamic loads on vehicle and bridge deck are measured by section model wind tunnel tests.Eight vertical and torsional flutter derivatives of bridge deck are identified by weighting ensemble least-square method.Finally,dynamic responses of the WVB system are analyzed in a series of cases.The results show that the accelerations of the vehicle are excited by the fluctuating wind and the track irregularity to a great extent.The transverse forces of wheel axles mainly depend on the track irregularity.The displacements of the bridge are predominantly determined by the mean wind and restricted by its stiffness.And the accelerations of the bridge are enlarged after adding the fluctuating wind.     

Elastic-plastic seismic response of CRTS II slab ballastless track system on high-speed railway bridges

China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than rail. And the track-bridge interaction is weakened by the sliding layer installed between base plate and bridge deck. In order to study the dynamic response of CRTS II slab ballastless track on bridge under seismic action, a 3D nonlinear dynamic model for simply-supported bridges and CRTS II track was established, which considered structures such as steel rail, fasteners, track plate, mortar layer, base plate, sliding layer, bridge, consolidation, anchors, stoppers, etc. Then its force and deformation features under different intensities of seismic excitation were studied. As revealed, the seismic response of the system increases with the increase of seismic intensity. The peak stresses of rail, track plate and base plate all occur at the abutment or anchors. Both track plate and base plate are about to crack. Besides, the rapid relative displacement between base plate and bridge deck due to the small friction coefficient of sliding layer is beneficial to improve the seismic performance of the system. During the earthquake, a large vertical displacement appears in base plate which leads to frequent collisions between stoppers and base plate, as a result, stoppers may be damaged.     

轨道刚度不平顺对高速车-轨-桥系统振动的影响

轨道刚度不平顺从轨面上难以区分,当列车通过时则会产生巨大的轮轨冲击或轨道变形,严重影响系统的安全平稳运营。针对该问题,首先解析推导了轨道刚度不平顺的数学表达式,并基于列车-轨道-桥梁动力相互作用理论建立了高速列车-板式轨道-轨桥耦合动力学模型;在此基础上从时域和频域角度研究了常规型轨道刚度不平顺对系统的影响;并以扣件失效为例,研究了缺陷型轨道刚度不平顺对系统动态特性的影响规律。结果表明:轨道刚度不平顺对系统振动有明显影响;轮轨力、轮对加速度及构架沉浮加速度等列车振动响应明显,表现出扣件间距及轨道板长度的周期性影响;在所考察的指标中,构架点头加速度对轨道刚度不平顺最为敏感;当考虑结构弹性后,轨道板边缘位置处的振动较板中位置处的振动大,两位置处钢轨加速度幅值比为1.17,而轨道板的加速度比值则达到了2.2;常规型轨道刚度不平顺主要引起结构周期振动,可能导致系统共振,加速结构损伤;缺陷型轨道刚度不平顺会造成轮轨冲击,严重时导致轮轨垂向力和轮重减载率超标,威胁行车安全;列车在250~350 km/h之间速度运行时,失效扣件的数量最多为1个。     

既有简支铰接空心板梁桥结构状况动力评估

以湖南长沙湘江北大桥西引桥为工程实例,对既有简支铰接空心板梁桥结构状况动力评估方法进行了研究。首先根据梁格法基本原理,通过使虚拟横梁在同一铰接缝处的梁端竖向约束相互耦合来模拟纵向铰接缝,提出了改进的梁格模型,建立了简支铰接空心板梁桥动力特性空间分析模型,计算得出了桥梁结构的动力特性;然后通过实桥动力试验验证了计算模型的正确性,介绍了动力评估试验内容、测试方法以及测试结果。分析结果表明：该桥的动力系数都在规范要求内,桥梁结构状况良好,本文方法可为既有简支铰接空心板梁桥的结构状况评估提供有效手段。     

Damage alarming of long-span suspension bridge based on GPS-RTK monitoring

Structure damage identification and alarming of long-span bridge were conducted with three-dimensional dynamic displacement data collected by GPS subsystem of health monitoring system on Runyang Suspension Bridge.First,the effects of temperature on the main girder spatial position coordinates were analyzed from the transverse,longitudinal and vertical directions of bridge,and the correlation regression models were built between temperature and the position coordinates of main girder in the longitudinal and vertical directions;then the alarming indices of coordinate residuals were conducted,and the mean-value control chart was applied to making statistical pattern identification for abnormal changes of girder dynamic coordinates;and finally,the structural damage alarming method of main girder was established.Analysis results show that temperature has remarkable correlation with position coordinates in the longitudinal and vertical directions of bridge,and has weak correlation with the transverse coordinates.The 3%abnormal change of the longitudinal coordinates and 5%abnormal change of the vertical ones caused by structural damage are respectively identified by the mean-value control chart method based on GPS dynamic monitoring data and hence the structural abnormalities state identification and damage alarming for main girder of long-span suspension bridge can be realized in multiple directions.     

弹性系统动力学总势能不变值原理及其在振动和动力稳定性分析中的应用

讨论了拉格朗日方程和哈密顿原理的不足 ,介绍了由曾庆元 2 2年前首次提出的弹性系统动力总势能不变值原理及形成系统矩阵的“对号入座”法则 ,阐明了不论系统如何复杂 ,其空间振动方程均可利用此原理和此法则简便建立 .它们独特的优点体现在解决了列车 桥梁 (或列车 轨道 )时变系统横向振动的问题 ,而这两个复杂动力系统的空间振动方程不能由动静法、拉格朗日方程或哈密顿原理等方法建立 .曾庆元和他的研究生们将列车 桥梁 (或列车 轨道 )视为一个整体系统 ,利用前述原理和法则建立了此系统的空间振动方程 ,在国内外首次求得了桥梁和轨枕的振动波形图 ,与相应的实测波形图良好接近 .文末提出了弹性动力系统总势能的概念 ,基于此概念 ,又提出了判别系统运动稳定性的能量准则 ,两个例题说明了此能量准则的应用 .     

移动荷载作用下加筋路堤和轨道系统的三维动力响应

用解析法研究了加筋路堤上轨道系统在移动荷载作用下的三维动力响应问题。基于Biot多孔弹性介质的波动理论,建立了加筋路堤轨道系统分析模型。将钢轨简化为无限长弹性Euler梁,将枕木简化为连续质量块,将加筋路堤作为一横观各向同性层来考虑,将下卧土体考虑为由Biot波动方程描述的饱和半空间。联立轨道系统、加筋路堤和下卧土体的动力方程,在Fourier变换域内求解荷载作用下钢轨位移和土体位移的表达式,将求得的表达式进行Fourier逆变换得到其在时域里的表达式。研究了列车移动速度、加筋路堤层的厚度、荷载幅值大小和加筋率等对路堤及轨道系统动力响应的影响。计算结果表明,钢轨竖向变形随着速度的增大呈现先增大后减小的趋势;加筋路堤上的钢轨竖向变形显著小于同厚度下未加筋路堤上的钢轨竖向变形;钢轨竖向变形随着荷载幅值的增大而增大;随着加筋率的增大而减小。     

Effect of cross-wind on spatial vibration responses of train and track system

By taking cross-wind forces acting on trains into consideration, a dynamic analysis method of the cross-wind and high-speed train and slab track system was proposed on the basis of the analysis theory of spatial vibration of high-speed train and slab track system. The corresponding computer program was written by FORTRAN language. The dynamic responses of the high-speed train and slab track under cross-wind action were calculated. Meanwhile, the effects of the cross-wind on the dynamic responses of the system were also analyzed. The results show that the cross-wind has a significant influence on the lateral and vertical displacement responses of the car body, load reduction factor and overturning factor. For example, the maximum lateral displacement responses of the car body of the first trailer with and without cross-wind forces are 32.10 and 1.60 mm, respectively. The maximum vertical displacement responses of the car body of the first trailer with and without cross-wind forces are 6.60 and 3.29 mm, respectively. The maximum wheel load reduction factors of the first trailer with and without cross-wind forces are 0.43 and 0.22, respectively. The maximum overturning factors of the first trailer with and without cross-wind forces are 0.28 and 0.08, respectively. The cross-wind affects the derailment factor and lateral Sperling factor of the moving train to a certain extent. However, the lateral and vertical displacement responses of rails with the cross-wind are almost the same as those without the cross-wind. The method presented and the corresponding computer program can be used to calculate the interaction between trains and track in cross-wind. Foundation item: Project (2007CB714706) supported by the Major State Basic Research and Development Program of China; Project (50678176) supported by the National Natural Science Foundation of China; Project (NCET-07-0866) supported by the New Century Excellent Talents in University     

考虑信噪比和车-桥耦合效应的桥梁健康监测策略

为了舍弃大量信噪比低或无异常的数据,节约计算资源并提高分析效率,在理论依据的基础上实现具有针对性的桥梁健康监测,提出了考虑信噪比和车-桥耦合效应的桥梁监测策略.对监测信号成分进行分析,指出为了实现监测策略,需要根据车-桥耦合动力理论确定合理准确的监测阈值.将车群等效为具有主体部分和耦合均布质量的时变动力模型,建立桥梁结构与移动车群相耦合的动力平衡方程及其解析表达式.以一实际简支梁健康监测为例,根据车-桥耦合理论分析车群的均布质量、行驶速度以及振动频率对桥梁动力反应的影响,并结合实际监测数据确定监测阈值,实现监测策略.实验结果表明该监测策略有效.     

列车-曲线桥梁系统耦合振动分析

为进一步研究列车-曲线桥梁系统耦合振动特性,基于车辆-桥梁/轨道系统动力相互作用分析理论,采用模态叠加法建立列车-曲线桥梁系统的空间耦合振动方程.沿轨道中心线建立移动坐标系,借助坐标转换,确定列车通过曲线桥梁时的几何位置关系; 考虑列车曲线运动特点,基于赫兹弹性接触理论和卡尔克(Kalker)蠕滑理论,解决列车曲线运动时的轮轨接触耦合关系,并对广义力向量进行修正; 采用龙格库塔积分法求解列车-曲线桥梁的动力响应.依据以上理论,研究了曲率半径、曲线超高以及车速对列车-曲线桥梁耦合振动响应的影响规律.分析结果表明:桥梁和列车的振动响应随车速的增大而增大,随着曲线半径的增大而减小.桥梁的振动响应不随曲线超高的增大而变化,列车的振动响应在平衡超高和过超高时较小.