温度变形对大跨度钢箱系杆拱桥车桥动力响应的影响

为分析温度变形对大跨度钢箱系杆拱桥列车走形性的影响,以某跨度为96m的四线下承式钢箱系杆拱桥为例,首先建立该桥的动力分析模型并对其进行自振特性分析,然后,根据弹性系统动力学势能不变值原理与形成矩阵的“对号入座”法则,分别考虑桥梁在3种温度体系（未考虑温度、升温、降温）下产生的变形影响,将其以组合曲线的形式叠加到轨道不平顺中进行列车走行性分析,建立车桥系统的空间振动方程,并对3种工况下的车桥耦合动力响应进行计算分析。研究结果表明：温度变形对桥梁动力响应的影响不大,对列车响应中脱轨系数、横向力、车体横向加速度及横向sperling指标有显著的影响,但在各温度变形工况下列车走行性仍满足限值要求。     

Theoretical and experimental excitation force spectra for railway-induced ground vibration: vehicle–track–soil interaction,irregularities and soil measurements

Excitation force spectra are necessary for a realistic prediction of railway-induced ground vibration. The excitation forces cause the ground vibration and they are themselves a result of irregularities passed by the train. The methods of the related analyses – the wavenumber integration for the wave propagation in homogeneous or layered soils, the combined finite-element boundary-element method for the vehicle–track–soil interaction – have already been presented and are the base for the advanced topic of this contribution. This contribution determines excitation force spectra of railway traffic by two completely different methods. The forward analysis starts with vehicle, track and soil irregularities, which are taken from literature and axle-box measurements, calculates the vehicle–track interaction and gets theoretical force spectra as the result. The second method is a backward analysis from the measured ground vibration of railway traffic. A calculated or measured transfer function of the soil is used to determine the excitation force spectrum of the train. A number of measurements of different soils and different trains with different speeds are analysed in that way. Forward and backward analysis yield the same approximate force spectra with values around 1 kN for each axle and third of octave.     

Influence of uneven rail irregularities on the dynamic response of the railway track using a three-dimensional model of the vehicle–track system

A mathematical model of the vehicle–track interaction is developed to investigate the coupled behaviour of vehicle–track system, in the presence of uneven irregularities at left/right rails. The railway vehicle is simplified as a 3D multi-rigid-body model, and the track is treated as the two parallel beams on a layered discrete support system. Besides the car-body, the bogies and the wheel sets, the sleepers are assumed to have roll degree of freedom, in order to simulate the in-plane rotation of the components. The wheel–rail interface is treated using a nonlinear Hertzian contact model, coupling the mathematical equations of the vehicle–track systems. The dynamic interaction of the entire system is numerically studied in time domain, employing Newmark's integration method. The track irregularity spectra of both the left/right rails are taken into account, as the inputs of dynamic excitations. The dynamic responses of the track system induced by such irregularities are obtained, particularly in terms of the vertical (bounce) and roll displacements. The numerical model of the present research is validated using several benchmark models reported in the literature, for both the smooth and unsmooth track conditions. Four sample profiles of the measured rail irregularities are considered as the case studies of excitation sources, examining their influences on the dynamic behaviour of the coupled system. The results of numerical simulations demonstrate that the motion of track system is significantly influenced by the presence of uneven irregularities in left/right rails. Dynamic response of the sleepers in the roll direction becomes more sensitive to the rail irregularities, as the unevenness severity of the parallel profiles (quantitative difference between left and right rail spectra) is increased. The severe geometric deformation of the track in the bounce–pitch–roll directions is mainly related to such profile unevenness (cross-level) in left/right rails.     

客货共运线路轨道不平顺不利波长的分析研究

我国铁路主要是客货共运线路,客车的速度可达140～160km/h,而货车的速度只有80km/h左右。货车与客车的车辆结构动力性能存在较大的差异,所以对轨道结构的几何形位的要求也有所不同。为了使客车和货车都能在同一线路上安全、平稳地运行,则必须对轨道不平顺与车辆运行平稳性和安全性之间的关系进行研究。本文利用计算机动力模拟仿真计算轨道不平顺激扰下客车和货车的动力响应,对轨道随机不平顺与不同类型车辆的车体加速度之间的关系进行了相干分析和功率谱分析,计算得出了引起客车和货车较大动力响应的轨道不平顺不利波长。然后对两者的不利波长进行了分析,归纳出了客货共运线路的轨道不平顺不利波长范围,为现场轨道不平顺的养护维修和管理提供了理论和实践指导。     

An efficient approach to the analysis of rail surface irregularities accounting for dynamic train–track interaction and inelastic deformations

A two-dimensional computational model for assessment of rolling contact fatigue induced by discrete rail surface irregularities, especially in the context of so-called squats, is presented. Dynamic excitation in a wide frequency range is considered in computationally efficient time-domain simulations of high-frequency dynamic vehicle–track interaction accounting for transient non-Hertzian wheel–rail contact. Results from dynamic simulations are mapped onto a finite element model to resolve the cyclic, elastoplastic stress response in the rail. Ratcheting under multiple wheel passages is quantified. In addition, low cycle fatigue impact is quantified using the Jiang–Sehitoglu fatigue parameter. The functionality of the model is demonstrated by numerical examples.     

考虑徐(温)变的连续梁拱桥车桥耦合振动分析

根据弹性系统动力学总势能不变值原理及形成矩阵的"对号入座"法则,考虑了连续梁钢管混凝土拱桥桥面因温度和徐变作用而产生的变形影响,将其以组合曲线的形式叠加到轨道不平顺中进行列车走行性分析,建立车桥系统振动方程。采用计算机模拟的方法,建立列车和桥梁动力分析的有限元模型,研究了桥面徐变变形及温度变形对车桥系统耦合振动的影响。结果表明:桥面的徐变及温度变形所致的线路不平顺对轮重减载率、车体竖向加速度和竖向Sperling指标的影响较为显著。因此,在评判桥上列车的运行安全和舒适性时,尤其对于高速铁路,应考虑混凝土徐变及温变产生的桥面变形引起的轨道不平顺影响。     

机车对轨道横向随机不平顺的响应

本文用谱分析方法，分析和计算了机车在直线轨道上匀速运行时对轨道横向随机不平顺输入的动力响应，计及了轨道的横向弹性及轮轨间的非线性几何关系。在计算中采用统计线性化方法和迭化法，将结果与线性情况作了比较。     

轨道复合不平顺对提速列车运行影响的研究

轨道几何形位不平顺是影响轮轨动态作用力和行车平稳性的主要因素之一,是当前高速重载和提速线路的主要研究内容.利用动力模拟仿真计算多种类型轨道单一不平顺、复合不平顺和随机不平顺激扰下提速车辆的动力响应,并着重分析轨道复合不平顺对提速列车运行安全性和平稳性的影响.对各种轨道不平顺条件下车辆动力响应的计算结果进行分析对比,找出相对不利的轨道不平顺类型及其波长和幅值,为现场控制各种类型轨道不平顺、制定提速线路轨道养护维修和不平顺管理标准提供理论依据.结果表明,方向和水平复合不平顺对车辆运行的安全性和平稳性的影响较大,是需要重点控制的轨道不平顺类型.     

250km／h高速铁路轨道不平顺的安全管理

利用根据车辆－轨道耦合动力学思想所建立车辆－轨道垂横耦合模型,在充分考虑多种波长并存的情况下,仿真计算了250km/h高速铁路各种轨道不平顺的管理目标值。计算结果与日本和德国高速铁路轨道不平顺的经验管理目标值基本一致。     

高铁常用跨度简支梁桥上轨道周期性不平顺影响分析

通过对桥梁徐变上拱设计和相应规定、轨道不平顺检测方法、实测资料以及线路规范的对比和理论计算,进行高铁常用跨度预应力混凝土简支梁桥上轨道产生波长为32 m的轻微周期性不平顺现象研究。结果表明:线路、桥梁规范中线路高低Ⅰ级管理值、梁跨竖向残余变形的规定是一致的;轨面不平顺静、动态检测结果不可以用来直接对比;京沪高铁桥上轨道周期不平顺的桥跨长度占比随着时间发展逐渐增大,开通4年后占比持平至约66%,桥上轨道周期性不平顺峰值均值、标准差及变异系数分别约为2.28 mm,0.57 mm和0.25;开通5年后98.4%,99.9%和100%的桥上轨道周期性高低不平顺峰值分别小于5,6和7 mm;当连续多跨简支梁徐变值均大于3 mm时,线路TQI高低已超过规范管理限值,建议通过轨面设置反预拱度,避免由梁体徐变带来的大面积轨道精调作业。