Investigating the Influence of Auxiliary Rails on Dynamic Behavior of Railway Transition Zone by a 3D Train-Track Interaction Model

Abstract Abrupt track vertical stiffness variations along railway tracks can lead to increased dynamic loads, asymmetric deformations, damaged track components, and consequently, increased maintenance costs. The junction of slab track and ballasted track is one of the existing areas where vertical track stiffness can suddenly change, therefore requiring a transition zone that smoothes the track stiffness change. One of the methods for constructing the transition zone at the junction of slab and ballasted tracks is to install auxiliary rails along the transition zone. In the present study, the dynamic behavior of this type of transition zone was evaluated by a train-track interaction model. For this purpose, a 3D model of the railway track was made, representing the slab track, the transition zone, and the ballasted track. Then, the modeling results were validated by the results of field tests. Afterwards, in order to study the dynamic behavior of the transition zone with auxiliary rails, different sensitive analyses, such as vehicle speed, vehicle load, number of auxiliary rails and railpad stiffness, were performed with the model. The obtained results showed that the use of auxiliary rails reduced the rail deflection variations along the transition zone from 35% to 28% for low and medium speeds (120, 160, 200 km/h), and from 40% to 33% for high speeds (250, 300 km/h).

摘要
轨道竖向刚度突变会引发动态荷载增大、轨道变形不对称、轨道部件损坏，进而导致养护成本上升。板式轨道（slab track）与有砟轨道（ballasted track）的衔接段是现有轨道竖向刚度易发生突变的区域之一，因此需要设置过渡区以平缓轨道刚度变化。在板式轨道与有砟轨道衔接处设置过渡区的方法之一，是沿过渡区铺设辅助轨（auxiliary rails）。本研究通过列车-轨道耦合动力学模型（train-track interaction model），对该类过渡区的动力学特性进行了评估。为此，构建了涵盖板式轨道、过渡区与有砟轨道的三维轨道模型。随后通过现场试验结果对建模结果进行了验证。此后，为研究铺设辅助轨的过渡区的动力学特性，本研究基于该模型开展了多组敏感性分析，涉及列车速度、列车荷载、辅助轨数量以及轨道垫板（railpad）刚度等变量。研究结果表明，铺设辅助轨可使过渡区的钢轨挠度变异率在中低速（120、160、200 km/h）下从35%降至28%，在高速（250、300 km/h）下从40%降至33%。