Dynamic Behavior of the Transition Zone of an Integral Abutment Bridge

Weaker sections of a railway track, such as the approach sections, are prone to differential settlement under the action of repeated train loads. The railway tracks degrade more quickly at a critical section adjacent to a traditional rail bridge because of progressive deterioration. Opting for an integral abutment instead of a traditional bridge is gaining importance due to its improved performance in terms of track stiffness and reduced settlement. It is essential to understand such issues with the appropriate methodologies. This study investigates the behavior of an integral abutment bridge with the transition zone subjected to train loading. Generally, the transition zone is a two-part wedge section consisting of unbound granular material and cement bound mixture. A field monitored traditional abutment bridge system is used to validate the developed two-dimensional Finite Element (FE) model. The model is further developed to simulate the dynamic behavior of the transition zone against the varying speeds of the train. The parametric study is performed on the transition zone by varying its geometric configurations and considering different materials for the backfill. The results indicate that the trapezoidal approach slab influences the track displacement significantly. The transition zone thickness and material properties of the backfill have a greater effect on the overall track response. Based on the results, the stable transition zones are identified to cater to the gradual stiffness variation during train–track interaction.