ADYTrack: Development of a Railroad Trackbed Model and Parametric Study of Track Modulus

Abstract

Deformation prediction of railroad trackbed has always been a challenge for the railroad designers and engineers. There are many complex interactions take place simultaneously between superstructure and subgrade of railways trackbed, which simply make the deformation predictions harder. Numerical models offer an alternative to simulate the performance of the substructure of railroad with considerable accuracy. In this paper, a finite element based three-dimensional (3D) model has been developed in MATLAB. This model has the capability to study the effects of track modulus, subgrade modulus, interactions between track and soil, the track geometry, and the wheel loads. The rails and ties are modelled as two node beam (line) elements and the substructure (ballast, subgrade etc.) is modelled as eight node isoperimetric hexahedron brick elements. The rail-tie interaction is modelled using a liner elastic spring elements. The model was first calibrated against an identical model built ANSYS (APDL), a reliable commercial software. The results of the ADYTrack are further validated with other numerical models and full-scale field test results reported in the literature. Following successful validation, a detailed parametric study is conducted to study the response of track modulus for a typical All-Granular trackbed using practical range of values for the variables involved. Numerical analysis showed that subgrade resilient modulus substantially impacts the track modulus. Furthermore, the depth of the ballast, moment of inert