Stress-deformation analysis of rail substructure under moving wheel load

Abstract

A three-dimensional (3D) finite element (FE) analysis is developed to study the effect of moving wheel load on the dynamic response of track with the key objective of determining the accurate stress-deformation response of the substructure. The 3D FEM model is first calibrated and then validated with two independent set of field measurements. The computed transient displacements and vertical stresses corroborate well with the field data from the selected case studies, endorsing the reliability of the current numerical model. The changes attributed to dynamic stress paths and the angle of principal stress rotation are also analysed with respect to the train speed in the range, 60–450 km/h. The results show some limitations of the existing dynamic amplification factor in relation to the design of railway track. This traditional approach will only be appropriate when the train speeds are relatively low, but it will not be accurate at significantly higher speeds at which significant principal stress rotation occurs, resulting in correspondingly increased shear stresses. The current FEM model enables a limiting train speed to be determined to prevent shear failure of the ballast layer when the dynamic response in relation to ballast properties is interpreted based on the proposed R-wave speed /critical track speed ratio.