Dynamic responses of railway ballasted track considering rail pad deterioration

Rail pads, which can be made of polymeric compound, rubber, composite materials etc., are resilient components installed on rail seats between the rail and sleeper in order to attenuate the impact loads and moderate track stiffness at the special locations. Based on literature, rail pad can be deteriorated over time. This can change the dynamic characteristics of rail pads: stiffness and damping. This paper presents the dynamic responses of railway track with new rail pads and aged rail pads. It should be noted that the parameters used of rail pads were analysed using impact excitation technique and then adapted for this study. To study the dynamic responses, D-track software is used based on Winkler foundation principle. Wheel flat is considered as imperfect wheel for impact case. The results obtained show that rail pads deteriorations seem to have significant effects on the increasing of rail/sleeper contact force rather than wheel/rail contact force. It is know that softer pads normally have a better performance on reducing dynamic responses. Although, the stiffness of rail pads reduce over time, damping coefficient also decrease. These lead to a poor performance of rail pad resulting in the reducing of rail/sleeper contact force.