Analysis of a multi-Part Transition Zone Application in Railway Track by Numerical Method

Abrupt track vertical stiffness variations along railway tracks can lead to increased dynamic loads, asymmetric deformations, damaged track components, and consequently, increased maintenance costs. Therefore, such problems must be reduced by constructing a transition zone that smoothes the track stiffness change. 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. One of the innovative methods for constructing the transition zone at the junction of slab and ballasted tracks is implementation of the combined approach slab and 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, in order to study the dynamic behavior of the transition zone with combined approach slab and 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 combined approach slab and auxiliary rails reduced the rail deflection variations along the transition zone from 35% to 22%-28% for low and medium speeds (120, 200 km/h), and from 41% to 28.5%-33% for high speeds (300 km/h).