Three Dimensional Finite Element Model of Railway Ballasted Track System under Dynamic Train Loading

Abstract

There is a need for railway systems and upgrade their infrastructure to meet the future growing demand. This would expand the railway network by planning new track routes to increase the efficiency of railway transportation by running behavior of high train speeds between urban cities. The track/ballast; sleepers; and subgrade foundation system are important superstructure parts that need to be upgraded and improved to withstand high train speeds. A numerical finite element technique significantly benefits in simulating the impact of the dynamic response and predicting the deformation and stress distribution in the railway ballasted system. A three-dimensional finite element program PLAXIS ver. (20) have been utilized in this research to analyze the track of complex behavior under train loading. The vertical displacement of 3.8 mm was obtained at the rail/wheel contact point and greater than at the ballast embankment by about (19%) and (37%) for the subgrade foundation. Also, the maximum value of vertical displacement corresponds with the movement path of the train load is reduced laterally as the distance from the track centerline increases. The maximum vertical acceleration of 15.2 m/s2 was obtained at surface points under track loading and decreased gradually with increased depth below the ballast embankment layer to reach a minimum value of 1.2 m/s2. The vertical deformation was 1.3 mm, 2 mm, and 3.9 mm for 40 km/hr, 50 km/hr, and 60 km/hr respectively, and increased rapidly to 15 mm for train velocity greater than 70 km/hr due to the significant increase in train vibration level at higher speed. A critical train speed of 70 km/hr was observed that promoted the level of vibration and magnified the area of influence.