Investigations on the Effects of Rail Longitudinal Forces in Train-Track Dynamic Interaction

Nowadays, attention to railways has been increased as one of the important transportation methods. Various factors can cause longitudinal forces on the railway tracks, so the most important factors are the temperature changes due to the rail contraction and expansion (thermal forces), train braking system forces and acceleration, etc. Increasing longitudinal force can lead to buckling phenomena in railway tracks. In this paper, the effects of tensile and compressive longitudinal forces on the parameters of rail, sleeper, and ballast layers under vertical moving loads are investigated by using the finite element method. In this regard, by performing sensitivity analyses for different values of longitudinal forces and train speeds dynamic responses (displacement, velocity, and acceleration) of railway track components like rail, sleeper, and ballast have been studied. The results show that increasing the values of longitudinal axial force from –2000 [kN] up to 2000 [kN] as well as increasing the train speed from 10 [m/s] (36 [km/h]) up to 100 [m/s] (360 [km/h]) increases the rail displacement and velocity in the range of 25% up to 37% also the rail acceleration in the range of 9% up to 14%. The velocity and acceleration of the sleeper also the ballast velocity increase in the range of 24% up to 30% and 7% up to 9%, respectively, by increasing the speed of the train from 10 [m/s] (36 [km/h]) to 100 [m/s] (360 [km/h]) in all three modes without applying axial force, considering compressive and tensile one in the train-track interaction system.