Mitigation of vibrations and differential settlements at railway bridge transition zones using micropiles

Abstract

This study investigates the dynamic behaviour and mitigation strategies for railway bridge transition zones, which are critical regions prone to accelerated track degradation due to abrupt changes in substructure stiffness and damping. Such zones experience heightened train impact forces, leading to increased vibrations and differential settlements that compromise safety and necessitate frequent maintenance. Through the development and validation of detailed 3D numerical models calibrated with field data, this research examines the influence of train speed, axle load, and transit direction on track stability under high-speed and heavy freight conditions. The findings reveal that increasing train speed and axle load significantly exacerbate vibrations and track settlements, elevating derailment risks. Notably, the application of micropiles beneath the track at approach zones demonstrates a substantial reduction in differential settlements up to 57%, surpassing many existing mitigation techniques. Additionally, optimising micropile dimensions and spacing effectively diminishes dynamic forces at the track-bridge interface, thereby enhancing the overall stability and safety of high-speed and heavy freight railway operations across transition zones.