An Improved Cohesive Zone Model for Interface Mixed-Mode Fractures of Railway Slab Tracks

Abstract

The interface crack of a slab track is a fracture of mixed-mode that experiences a complex loading–unloading–reloading process. A reasonable simulation of the interaction between the layers of slab tracks is the key to studying the interface crack. However, the existing models of interface disease of slab track have problems, such as the stress oscillation of the crack tip and self-repairing, which do not simulate the mixed mode of interface cracks accurately. Aiming at these shortcomings, we propose an improved cohesive zone model combined with an unloading/reloading relationship based on the original Park–Paulino–Roesler (PPR) model in this paper. It is shown that the improved model guaranteed the consistency of the cohesive constitutive model and described the mixed-mode fracture better. This conclusion is based on the assessment of work-of-separation and the simulation of the mixed-mode bending test. Through the test of loading, unloading, and reloading, we observed that the improved unloading/reloading relationship effectively eliminated the issue of self-repairing and preserved all essential features. The proposed model provides a tool for the study of interface cracking mechanism of ballastless tracks and theoretical guidance for the monitoring, maintenance, and repair of layer defects, such as interfacial cracks and slab arches.

Influence of temperature gradient of slab track on the dynamic responses of the train-CRTS III slab track on subgrade nonlinear coupled system

“…Some scholars adopted the measured or calculated time-varying temperature loads to research ballastless track’s mechanical performance and damage. Zhong et al 21 , 22 imported the measured time-varying temperature loads to a 3D FEM of CRTS II slab track to investigate the curling behaviors as well as the interface stresses in the construction stage due to the daily changing temperature. Zhu et al 23 studied the mechanical characteristic and interface damage evolution of DB ballastless track under the cyclic time-varying slab temperature gradient load based on the meteorological data of Guangzhou district in China in the year 2001.…”

“…At present, many studies have been conducted on the temperature distributions of ballastless track, and the deformation, mechanical, and damage characteristics of ballastless track, which were caused by the temperature load of ballastless track or by the combined train and temperature loads of ballastless track. However, most of these studies focused on CRTS I 25 , 26 , CRTS II 5 , 9 – 14 , 16 – 22 , 24 , 27 – 31 slab track, and DB ballastless track 6 , 7 , 15 , 23 . While few studies focused on CRTS III slab track 8 .…”