Laboratory Investigation of the Temperature-Dependent Mechanical Properties of a CRTS-Ⅱ Ballastless Track-Bridge Structural System in Summer

Abstract

To study the mechanical properties of the China Railway Track System type II (CRTS-II) ballastless slab track structure, a 1/4-scale specimen of a CRTS-II slab ballastless track-32-m standard prefabricated simply supported box girder bridge with three spans and two high-speed railway lines was developed. The mechanical properties of the structure under the action of daily natural temperatures were studied under the natural environmental conditions. The structural strain and relative interlayer displacements were analyzed. The results show that the temperature of the CRTS-II ballastless track-bridge structural system changes periodically every 24 h. The strain of the structural layers of the track system first increases and then decreases sinusoidally, and the internal strain of the track system lags along the vertical depth direction. The relative displacement between the layers of the ballastless track bridge structure system increases with the increase in temperature. The extreme value of the vertical relative displacement appears between the track bed and the bridge at section 1/4 in the span, so it should be paid attention to by the maintenance personnel. Due to the constraint of the shear slots, the structural strain and relative displacement at the fixed end near the shear slots are smaller than those at the sliding end. The mid-span deflection is the largest, and the overall deflection during the cooling phase is more significant than that during the heating phase.

Mechanical Performance of a Ballastless Track System for the Railway Bridges of High-Speed Lines: Experimental and Numerical Study under Thermal Loading

“…The overall temperature action causes the expansion, while temperature gradient causes flexural deformations in the structure [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. The changes in ambient temperature cause temperature changes within the track structure, and a complex thermal field is generated inside the structural system [ 21 , 22 , 23 , 24 , 25 ]. Regarding the thermal field in the track slab, Gao Liang et al [ 19 ] studied the characteristics of track slab surface temperature following the change of ambient temperature through long-term temperature monitoring and formulated a relationship between track slab surface temperature and ambient temperature using a quartic polynomial and exponential distribution model.…”

“…The existing literature [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ] mainly discusses ballastless track temperature field prediction and the damage characteristics of the track structure under thermal load. There are, however, scant studies on the internal causes of ballastless track damage under thermal load.…”