Influence of emulsified cement asphalt mortar seam on dynamic characteristics of vehicle-China railway track system II ballastless track system

Emulsified cement asphalt mortar (CA mortar) seam is a common defect in the running of China Railway Track System II (CRTS II) slab ballastless track, and this error affects safety during high-speed driving. The influence of CA mortar seam on track structural performance is analyzed on account of the temperature and static loads of the train in previous studies. To explore the influence law of CA mortar seam on the safety of vehicle-CRTS II slab ballastless track system under dynamic load, a nonlinear finite element model for the vehicle-CRTS II slab ballastless track-subgrade system under track irregularity is proposed in this study. The finite element calculation models for vehicle-CRTS II slab ballastless track and seam were respectively established on the basis of the coupling dynamics of wheel rail system and finite element method. MATLAB program was also compiled to simulate the track irregularity of medium-long wave and short wave. The system model and track irregularity were then both applied to ABAQUS numerical analysis. The influence of CA mortar seam on the system dynamic characteristics with different train speeds, seam lengths, and heights was studied. Results show that when the train speed is 300 km/h, the length of seam is 1.2 m and the height of seam is 3 mm. The seam exerts minimal effect on the dynamic characteristics of the vehicle system, which significantly influences the vertical acceleration of track slab, with an increase of 144.3%; the higher the train speed, the greater the dynamic response of vehicle and track system, and the greater the influence of seam on driving safety; the vehicle dynamic response of rail and track slab increases with the increase of the length of seam, which is significant when the seam length is more than 1.2 m. When the seam height tends to 1 mm, the dynamic response of rail and track slab increases significantly and then stabilizes. This study provides theoretical reference for the safety assessment of slab ballastless track. © 2017 Eastern Macedonia and Thrace Institute of Technology.