Numerical analysis of temporal effect of ballast shoulder cleaning

Abstract

The paper presents a numerical analysis to investigate the temporal effect of shoulder cleaning on ballast drainage performance at various fouling conditions. Two parameters, the fouling index (FI) and the fouling profile (FP) are proposed to quantitatively represent the fouling conditions. A computational fluid dynamics (CFD) model including the Darcy-Forchheimer’s law to take into account the effect of porous medium is developed. Prior experimental results are used to extract model configuration parameters for improved simulation accuracy. Parametric simulations are carried out to evaluate flow characteristics through the ballast layer before and after shoulder cleaning for different FIs and FPs. Service life-dependent mathematical models of FI and FP are also introduced to capture the temporal effect of shoulder cleaning on drainage performance. Our analysis indicates that the optimal maintenance schedule needs to be decided with a balanced consideration of both the drainage health and the potential of drain restoration during the service life.