基于车辆-轨道单元的无砟轨道动力特性有限元分析

根据CRTSⅡ型无砟轨道系统结构特点,建立列车-轨道-路基耦合系统动力分析模型,提出一种包含钢轨、扣件、轨下垫板、预制轨道板、CA砂浆层、混凝土支承层及路基的无砟轨道单元,并推导该单元刚度矩阵、质量矩阵和阻尼矩阵。运用Lagrange方程建立高速列车通过时无砟轨道动力特性分析的有限元数值方程。结合实例,研究无砟轨道轨下垫板、CA砂浆层、路基等结构参数对轨道振动的影响,并对有砟轨道与无砟轨道连接段动力特性进行分析,分析时考虑列车速度、轨道基础刚度等影响因素。计算结果表明:无砟轨道结构参数合理取值与刚度合理匹配可显著提高轨道整体工作性能;连接段轨道基础刚度变化对钢轨垂向加速度和轮轨作用力均有影响,其影响随列车速度提高而增大;连接段采取轨道刚度渐变过渡措施,可明显降低车辆-轨道结构冲击振动,有效改善行车品质。

Analysis on Dynamic Behavior of Ballastless Track Based on Vehicle and Track Elements with Finite Element Method

According to the structural characteristics of CRTSⅡ Slab Ballastless Track system,the dynamic analysis model for the vehicle-track-subgrade coupling system is established and a new type of ballastless track elements is presented,which includes the rail,rail fastening,rail pad,prefab slab,CA mortar layer,HGT layer and subgrade.The stiffness matrix,mass matrix and damping matrix associated with the ballastless track element are deduced.By means of the Lagrange equation,the finite element method for analysis of dynamic behavior of ballastless track with high-speed trains passing through is developed.By use of numerical examples,the influence of structural parameters of ballastless slab track including rail pad,CA mortar layer and subgrade on track vibration and the dynamic behavior of track connection between ballast track and ballastless track in consideration of influencing factors such as the train speed and track foundation stiffness are investigated.The calculated results show as follows: Finding the reasonable values of structural parameters of ballastless track to well match its stiffness will improve the performance of the whole track system;changes in the track foundation stiffness of track connection have influence on the vertical rail acceleration and wheel-rail contact force and the influence increases with raising of the train speed;track connection stiffness is made to change gradually,thus reducing vehicle and track vibration significantly and improving train running quality effectively.