The influence of random sleeper spacing and ballast stiffness on the vibration behaviour of railway track

The foundation of a railway track, formed of railpads, sleepers and ballast , has crucial effects on the rail vibration properties. Usually, the sleepe r spacing and ballast stiffness are treated as uniform and represented by c onstant parameters in theoretical analyses. However, in reality they are ir regular and should be represented by different values at each support point . In this paper, the sleeper spacing and ballast stiffness are treated as r andom variables and their effects on the rail vibration are explored throug h numerical simulations. The statistical results show that the point recept ance and the vibration decay rate are distributed in a certain area instead of having a fixed value due to the variability in the sleeper spacing and ballast stiffness. It is found that the phenomenon of the pinned-pinned res onance may be suppressed by the random sleeper spacing. However, by studyin g the average vibration due to the interaction with a wheel, it is shown th at the random foundation has no significant effect on the average noise rad iated by the track.