【作者】 胡萍；

【导师】 王永和； 卿启湘；

【作者基本信息】 中南大学 ， 道路与铁道工程， 2010， 博士

【摘要】 路基过渡段是整个高速铁路上影响线路平顺性的一个非常重要部位。设计时速为350km/h的武广高速铁路,设计标准更高,要求更严。过渡段的合理设计成为了保证线路安全和旅客舒适性的关键,而列车作用下过渡段的动力特性研究则成为了验证过渡段设计是否合理的重要指标。考虑到武广高速铁路平均每隔45m出现—过渡段的情况,密集过渡段间的相互影响也成为了当今高速铁路研究的一个重点。本文以武广高速铁路过渡段为研究对象,以国家自然科学基金项目和铁道部科技计划为依托,通过室内外试验获取了过渡段材料参数和刚度比,利用现场大型行车试验分析过渡段动力特性规律,并由实测轨道加速度数据数定得到了轨道应力时程曲线,结合ANSYS参数化编程建立了过渡段轨道/路基动力有限元分析模型。另外,结合有限元法和模态叠加法,采用FORTRAN语言编制了列车/轨道/路基动力分析程序,研究了列车作用下过渡段的动力特性影响因素及密集过渡段间相互的影响。主要的研究工作和研究成果如下：(1)搜集了国内外过渡段所产生的问题及处理方法,并对普通轨道/路基和过渡段轨道/路基动力响应的研究历史与现状进行回顾和总结,提出了需要开展研究的问题。(2)通过现场波速试验(跨孔法、下孔法及面波法)、大型激振试验及室内大型粗颗粒土的物理力学试验,得到了路-桥过渡段基床表层和底层填料的动力参数和物理力学参数,并通过综合刚度法计算得到路-桥过渡段的刚度比。通过对比不同试验方法的试验结果,提出了较为合理的参数获取试验方案。(3)基于D’Alembert原理的弱变分和整体Lagrange格式,首先分析研究对象的本构模型、材料阻尼、CA砂浆单元选取、不同单元的连接,并引入了粘弹性人工边界,充分利用实测钢轨加速度,结合傅立叶变换等方法数定得到轮轨垂向力,作为动荷载输入,从而改进了现有无砟轨道路-桥过渡段系统半无限三维空间动力有限元计算模型。整体刚度矩阵方程的求解采用了Newmark |隐式积分法,因计算模型中包含有大量的耦合约束方程,采用了波前(Front)求解器和缩减法求解器,整个求解是在ANSYS系统中进行的。(4)通过建模和有限元分析提取模型的振型和频率,将有限单元法和模态综合叠加技术引入到车轨耦合振动模型中来。车辆采用六自由度的二维车辆模型,轨道采用平面梁单元建立连续梁模型,提取车轮行驶单元节点处振型向量,利用模态综合叠加法推导了系统矩阵,并建立了系统运动方程,这使得车轨耦合方程组矩阵维数大大降低,提高了求解速度,且避免了由于单元划分过细导致的轨道刚度矩阵和质量矩阵非常大而计算难以进行的问题。并用FORTRAN语言编制了相应的计算程序,运用所编制的程序与实测数据进行对比分析,结果表明该种方法确实可行,具有很强的通用性,且便于分析结构细部的动力响应。(5)在新建武广高速铁路综合试验段进行了两种车型120趟高速行车条件下的动力学测试,首次获得了最高速度达354.7km/h的路-桥过渡段动力响应试验数据。并引入小波分析理论,根据牛顿-柯特斯法积分法,五点三次平滑法,结合matlab软件编程,获取了更真实的动态时程响应曲线。为了获取动响应幅值,进一步对时程曲线进行随机数据信号的均方值、均值和方差的统计分析,并通过K检验法进行正态分布的假设检验；进一步验证数据的真实性,从而剔除部分不真实数据,获得真实信号。同时,对信号进行了频域分析,研究了过渡段的动态响应沿线路方向和路基深度方向的变化规律,并研究了轴重、行车速度、行车方向、邻线行车等对过渡段动力特性的影响。提出了过渡段路基动力设计的控制条件和动力分析控制标准,进而对过渡段的设计提出了建议。(6)根据国内外车辆轨道路基动力学特性的评价指标,利用第四章的过渡段轨道/路基动力模型,求得路-桥过渡段在列车荷载作用下轨道路基的动力响应,利用第五章模态叠加法建立的车辆/轨道/路基(地基)模型求得车辆/轨道的动力响应。以武广高速铁路轨道路基设计参数为基础,分析了过渡段长度、轨面弯折、差异沉降、过渡段刚度、过渡段型式等因素对过渡段动力指标的影响,并提出了相应的设计参考值。(7)借助于文中建立的过渡段动力有限元程序和模态叠加法编制的FORTRAN语言程序,对于不同间距的路-桥相邻过渡段进行动力分析,与实际工况的路-桥过渡段和现有评价标准进行对比,获得了最不利的过渡段间距范围,然后考虑极限工况,获得相邻路-桥过渡段的最不利间距,并进一步分析了“一次过渡法”和“二次过渡法”对密集过渡段进行处理的区别,得到了在最不利间距以内的相邻过渡段必须用“次过渡法”处理的重要结论。更多还原

【Abstract】 Transition section of subgrade is the weakness to interfere with smoothness of the tracks in the high-speed railway. Aimed at 350 km/h Wu-Guang passenger railway line whose design criterion is higher and requirement is more strictly, the reasonable design of transition section is the key to ensure the track safety and smoothness, and the dynamic performance research of transition section under high speed train is the important index to validate if it is designed in reason. Considering transition section appeared every 45m along the line. The research on effect between thick transition sections is the key stone and nodus in railway studies nowadays. The thesis which is supported in part as a project of National Natural Science Foundation of China (No:50678177) has studied the dynamic response characteristics of bridge-subgrade transition sections under the train load influence in Wu-Guang passenger line. The material parameters and stiffness ratio of bridge-subgrade transition section were obtained first by tests indoors and outdoors, then the dynamic performance rule of transition section was analysed to base on large-scale train tests in Wu-Guang passenger line.Introducing wheel-rail force established mathematically by rail acceleration, finite element analysis model of the track-subgrade was established by using ANSYS Parametric Design Language (APDL). In addition, extracting rail model parameters from finite model, vehicle-track-subgrade model were established by mode superposition method using FORTRAN language, and influential factors of dynamic performance of transition section and the influences between thick transition sections were analysed. The main research work of this dissertation can be summarized as follows.(1) Some problems and processing methods about transition section at home and abroad were analysed, The research history and development of track/subgrade dynamic response were reviewed, the problems existed were put forward.(2) Dynamic parameters and physical-mechanical parameters of subgrade were obtained by tests such as wave-velocity experiment, large vibration-exciting experiment and coarse-grain physico-mechanical tests. And stiffness ratio of bridge- transition section was obtained by synthetical stiffness method, the rational test schemes for getting the subgrade pamameters were put forward by comparing results from diffirent testing.(3) Based on variational (or weak) form of the equilibrium equations for the ballastless track-roadbed system in Galerkin method and total Lagrangian form, started to researched constitutive model, material damping model, element chosing for CA motar, various finite element coupling, and introducing visco-elastic artificial boundary, make the best of measured rail acceleration, then wheel-rail force were calculated by mathematical method such as Fourier transform. Finally, a semi-infinite tri-dimensional spatial timing coupled dynamic model has been improved and founded. The global matrices equations have been solved by implicit time integration of Newmark. Owing to many restricted equations being existed in the dynamic model, frontal solution is adapted to modal analysis, and reduced solution is adopted for transient dynamic analysis.(4) Extracting modal shape and frequency from finite element model, finite element method and mode superposition method were used to establish vehicle-track-subgrade model by FORTRAN program. It reduces the matrix dimentions of vechile-rail coupling equation and enhances computing speed. The result shows that the model is feasible and universal for analyzing dynamic performance in spatial structure details.(5) In-situ maesurements are performed on Wu-Guang passenger railway. During the tests, the train speed reaches to 354.7km/h, the dynamic responses under high-speed train load are obtained first. Introduced the wavelet analysis theory,on the basis of Newton-Cotes integration method,five-spot triple smoothing method,the real time-history curves were obtained with Matlab programs. In order to get the mean square value, mean value and variance of the response magnitude, the time-history curves were analysed statisticly and were hypotheses detected by K-test. Then the relationship between longitudinal distance,depth and dynamic response under different train speed were analysed.Some parameters are investigated which affect dynamic response of the system by utilizing this model, such as the axial load,train speeds, the train moving directions. The dynamic design-control conditions and dynamic analyse-control standard of transition section subgrade and some suggestions of designing transition section were put forward.(6) According to the track-rail dynamic performance evaluation index at home and abroad,the dynamic response of the vehicale, rail and roadbed were obtained by the established model in chater four and chapter five.Based on design parameters of roadbed in Wu-Guang passenger line, some parameters which affect dynamic response of the system were analysed, such as length of transition secion, differential settlement, the rigidity and the type of transition section and the corresponding reference value were put forward.(7) Dynamic performance of different spaces between two bridge-transition sections were analysed by mean of the rail-subgrade model of finite element and the vehicale-rail-subgrade model of FORTRAN language. It was compared with the dynamic performance of the real bridge-transition section and the evaluation criterion existing, and the better favorable space between two bridge-transition sections was obtained. Then the ultimate limit conditions were supposed to considering for calculating the dynamic performance of the transition section. Furtherly the different results were researched between "one transition" and "two transitions". The result shows that "one transition" is the rational disposal route for closely spaced transition section with the better favorable space.更多还原