Dynamic Response and Defect Identification of High-Speed Railway Ballastless Tracks and Subgrade under Settlement and Deformation

Abstract

The dynamic response law of ballastless track and subgrade of high-speed railway (HSR) under settlement deformation conditions is the key to identifying HSR subgrade diseases and evaluating the operation status of high-speed railway. This article utilizes the theories of multibody dynamics and continuum mechanics to construct a coupled calculation model of “train–ballastless track–subgrade,” achieving full process simulation of dynamic response under settlement conditions. The calculation results show a constant relationship between the wheel–rail force and the dynamic stress amplitude ratios on the surface and bottom of the track slab and base plate, which are 1.5, 0.901, 0.282, and 0.077, respectively. The wheel–rail force increases linearly with the increase of settlement amplitude and decays exponentially with the increase of settlement wavelength. Under different wheel–rail forces, the attenuation law of dynamic stress amplitude in the longitudinal direction is basically the same, with rapid attenuation. The attenuation law of velocity amplitude in the longitudinal direction is also basically the same, but the attenuation of velocity amplitude is not significant. Under the same wheel–rail force, the lateral dynamic stress amplitude of the track structure shows a saddle-shaped distribution, while the velocity amplitude distribution is basically the same. The research results of this article indicate that the dynamic stress response of the track structure can well reflect the operation status of high-speed rail, and provide key monitoring parameters and spatial positions for the operation status of high-speed rail subgrade. At the same time, the research results of this article can serve as a basis for the installation of track structure monitoring sensors.