Random vibration of train-track-ground system with a poroelastic interlayer in the subsoil

Abstract

A semi-analytical train-track-ground model considering rail irregularity is developed to study random vibration of the system. The ground is modeled as a layered half-space comprising two elastic layers, a poroelastic interlayer and a semi-infinite elastic half-space from top to bottom. Solution to the ground is derived adopting ‘adapted stiffness matrix method’. The ground is coupled with the track according to continuity conditions at the ballast-ground interface. The track-ground system is coupled with the train adopting Hertzian contact spring model. Pseudo-excitation method (PEM) is introduced to solve the random vibration induced by rail irregularity. The method is compared with existing research. Dynamic responses of the system such as amplitude, power spectral density (PSD) and standard deviation (SD) of displacement, velocity and acceleration are investigated. The existence of groundwater significantly influences vertical displacement for locations far from track center and long wavelength of rail irregularity, while it mainly affects the vertical velocity and acceleration for locations far from track center but short wavelength of rail irregularity. The maximum SD of vertical displacement increases with increasing speed, and no ‘critical speed’ exists for it when 0 m/s <c<200 m/s, which is different from the variation of vertical displacement with speed due to axle loads. High frequency components of the PSD of maximum vertical displacement, velocity and acceleration attenuate faster from the rail to the ground and with the distance from the track center on ground surface.