Modelling the influence of sub-grade material parameters on the response of railway line under moving train loads

The sub-grade of the railway track subjected to dynamic loading is governed by its dynamic material parameters, the basic dynamic material parameters are unit weight, Young’s modulus, Poisson’s ratio and the material damping. However, there is a need to identify the parameters of the sub-grade that has significant effect on the dynamic response of the railway track to achieve the specified technical requirements because the behavior of the sub-grade cannot be easily estimated or verified. Hence, this paper uses three-dimensional finite elements ABAQUS coupled with Artificial Non-Reflecting Boundary to investigate the effect of varying the unit weight, Young’s modulus, Poisson's ratio and the damping ratio of the sub-grade in the surface vibration induced at the embankment railway track in terms of Peak Vertical Velocity due to moving of the train loads. The input soil parameters used are soft clay, stiff clay, loose and dense uniform sand to demonstrate the parametric study. The predicated results show that both the Young’s modulus and damping ratio of the sub-grade have quite significant effect on the induced surface vibrations of railway track; while the influence of both unit weight and Poisson’s ratio are very small. Hence to fulfill the technical requirement of the railway track, special attention regarding to the Young’s modulus and the damping ratio of the sub-grade should be paid