High-speed railways (HSRs) are established all over the world owing to their advantages of high speed, ride comfort, and low vibration and noise. A ballastless track slab is a crucial part of the HSR, and its working condition directly affects the safe operation of the train. With increasing train operation time, track slabs suffer from various defects such as track slab warping and arching as well as interlayer disengagement defect. These defects will eventually lead to the deformation of track slabs and thus jeopardize safe train operation. Therefore, it is important to monitor the condition of ballastless track slabs and identify their defects. This paper proposes a method for monitoring track slab deformation using fiber optic sensing technology and an intelligent method for identifying track slab deformation using the random-forest model. The results show that track-side monitoring can effectively capture the vibration signals caused by train vibration, track slab deformation, noise, and environmental vibration. The proposed intelligent algorithm can identify track slab deformation effectively, and the recognition rate can reach 96.09%. This paper provides new methods for track slab deformation monitoring and intelligent identification.

To analyze the effects of differential subgrade settlement on the interface mechanical properties and damage behavior of the China Railway Track System (CRTS) II slab track, a three-dimensional finite element (FE) model considering the uneven support of the subgrade was developed. A cohesive zone model was used to simulate the interface damage between the precast slab and the cement asphalt (CA) mortar layer. The effects of settlement amplitude, wavelength, and temperature gradient were analyzed. The results indicated that the interface stress is significantly affected by the settlement amplitude. There exists a particular settlement wavelength that results in the maximum interface stresses. Considerable attention should be paid to the effect of the temperature gradient load, which may cause interface damage in the differential settlement region.