Abstract:
Railway track degrades more quickly in the transition zones between embankments and bridges, mostly due to the
development of settlements in the backfill. This amplifies the dynamic train/track interaction forces and accelerates the
deterioration of the components of both the track and the vehicles. Consequently, it induces additional maintenance
costs, reduces passenger comfort and, ultimately, it may affect train safety at transition zones. To address this problem
and to obtain more insight into the influence of the settlement profiles of the backfill in the train/track system, nonlinear
dynamic analyses were performed using a transition zone model to simulate different settlement profiles of the backfill.
In some cases, the results showed significant amplifications of axle accelerations and loads. In general, the greater
the number of hanging sleepers and their gap sizes, the higher the vertical accelerations of the sleepers and the
larger the vertical contact forces between the sleepers and the ballast layer. Settlement profiles associated with backfills
with a wedge shape seem to limit these negative aspects.
