Effect of vehicle speed on the dynamics of track transitions

摘要

When a railway track presents an abrupt discontinuity of vertical stiffness (e.g., due to the presence of a structure), an amplification of the dynamic forces acting on both the vehicle and the track may be expected. Therefore, diverse solutions-generally known as track transitions-have been proposed in the literature to provide a smoother stiffness change between different track sections. An extensive research has been performed in recent years in order to better understand the dynamics of track transitions as well as the processes involved. However, to the best of the authors' knowledge, no research has fully studied the effect of vehicle speed and only one value is generally used instead of considering a wider range. Hence, this paper explicitly analyzes the effect of train speed on the vibrational performance of four transition typologies: a concrete wedge; a hot mixed asphalt wedge; a geogrid; and a soil reinforcement. The results show that mitigation capacity of all the alternatives increases with train speed, the concrete wedge being the most effective solution. Moreover, the effects on vertical vibrations of the abrupt stiffness change are found to be significant only for high train speeds (220-300 km/h). Finally, an amplification effect due to resonance has been found for the concrete transition when a vehicle speed of 100 km/h is considered.