Abstract
To study the temperature distribution in the China Railway Track System Type II ballastless slab track on a high-speed railway (HSR) bridge, a 1:4 scaled specimen of a simply-supported concrete box girder bridge with a ballastless track was constructed in laboratory. Through a rapid, extreme high temperature test in winter and a conventional high temperature test in summer, the temperature distribution laws in the track on the HSR bridge were studied, and the vertical and transverse temperature distribution trend was suggested for the track. Firstly, the extreme high temperature test results showed that the vertical temperature and the vertical temperature difference distribution in the track on HSR bridge were all nonlinear with three stages. Secondly, the extreme high temperature test showed that the transverse temperature distribution in the track was of quadratic parabolic nonlinear form, and the transverse temperature gradient in the bottom base was significantly higher than that of the other layers of the track. Thirdly, the three-dimensional temperature distribution in the track on HSR bridge was a nonlinear, three-stage surface. Furthermore, similar regularities were also obtained in the conventional high temperature test, in which the temperature span ranges were different from those of the extreme high temperature test. In addition, the conventional high temperature test also showed that under the natural environment conditions, the internal temperature gradient in the track layers changed periodically (over a period of 24 h).
Highlights
The China Railway Track System Type II (CRTS-II) ballastless slab track is widely used in China’s national high-speed railway system, due to its various advantages, such as running comfort and high structural stability [1,2,3]
To ensure the continuity of the track with the high-speed railway (HSR) bridge and the consistency of the stress state, two supported concrete box girders with the same size and structural form were designed at both ends of the test specimen, forming a three-span ballastless track-bridge structural system, and the track was continuously arranged throughout the bridge
To study and compare the vertical temperature distributions of the CRTS-II ballastless track on the HSR bridge under different test conditions, the vertical temperature distribution curves when the maximum temperatures occurred were listed, and quadratic multinomial fitting was performed by the least square method
Summary
The China Railway Track System Type II (CRTS-II) ballastless slab track is widely used in China’s national high-speed railway system, due to its various advantages, such as running comfort and high structural stability [1,2,3]. The few studies on the temperature distribution in CRTS-II ballastless tracks on high-speed railway (HSR) bridges mainly focused on the theoretical solution under periodic climate conditions [29]. Established a thermodynamic analysis model of CRTS-II ballastless track based on finite element software and studied the vertical temperature distribution of the ballastless tracks under different climatic conditions, but due to the lack of accurate thermodynamic parameters of the CA mortar in the model, it was difficult to form a comprehensive understanding of the overall temperature distribution in the track. The existing research produced some satisfactory conclusions on the temperature distribution in the CRTS-II ballastless track-bridge system under high-temperature conditions [29], the research considered only the direct solar irradiation in natural climates, and the results presented a non-uniform temperature distribution. Using the temperature sensor system, the transverse and vertical temperature distributions in the track on a HSR bridge under different temperature conditions were studied, and the conclusions can provide references for the design of CRTS-II ballastless tracks and further understanding of the effect of temperature on CRTS-II ballastless tracks on HSR bridges
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