Probabilistic model and analysis of coupled train-ballasted track-subgrade system with uncertain structural parameters

Random dynamic responses caused by the uncertainty of structural parameters of the coupled train-ballasted track-subgrade system under train loading can pose safety concerns to the train operation. This paper introduced a computational model for analyzing probabilistic dynamic responses of three-dimensional (3D) coupled train-ballasted track-subgrade system (TBTSS), where the coupling effects of uncertain rail irregularities, stiffness and damping properties of ballast and subgrade layers were simultaneously considered. The number theoretical method (NTM) was employed to design discrete points for the multi-dimensional stochastic parameters. The time-histories of stochastic dynamic vibrations of the TBSS with systematically uncertain structural parameters were calculated accurately and efficiently by employing the probability density evolution method (PDEM). The model-predicted results were consistent with those by the Monte Carlo simulation method. A sensitivity study was performed to assess the relative importance of those uncertain structural parameters, based on which a case study was presented to explore the stochastic probability evolution mechanism of such train-ballasted track-subgrade system.