Modeling and Stress Analysis of Ballasted Tracks: Integrated Finite-Element and Discrete Support Techniques

This paper presents a computational study focused on establishing the criticality of rail cant in redistributing stresses within ballast tracks. A three-dimensional finite-element model (FEM) was developed and validated against field measurements to obtain railway track parameters and evaluate the dynamic amplification factor. These parameters were incorporated into a discrete support model (DSM) to analyze the dynamic stress response on the rail under moving wheel loads, with a particular emphasis on stress redistribution at critical rail sections. The integration of FEM with DSM was utilized for dynamic stress analysis, highlighting the novel aspect of investigating the influence of rail cant on the redistribution of rail stresses in ballasted railway tracks. The findings reveal that rail cant significantly influences stress distribution, with the gauge corner of the rail foot experiencing 36% higher stress than the field corner. Notably, this critical stress exceeds the allowable bending fatigue stress by 18% for a train speed of 300 km/h on an average track with a modulus of 20 MPa. Parametric studies further highlight the impact of subgrade layer depth on critical stress levels. The evaluated stresses align closely with field data, demonstrating the reliability of the proposed mathematical model for track design. Additionally, the model identifies a threshold for ballast and subgrade height beyond which rail stresses do not significantly change. This track design model offers valuable insights for improving the estimation of rail fatigue strength, ultimately enhancing railway track design.