The 4th Asian Concrete Federation Symposium on Emerging Technologies for Structural Longevity (ACF2023- ETSL)

273 / 2022-09-19 19:44:42

Temperature effects of CRTS II slab track under various field meteorological conditions

CRTS II slab track; Temperature effects; meteorological factors; heat transfer

Temperature effects of ballastless track in high-speed railway under complicated environment conditions become increasingly important, which are governed by a number of meteorological factors, including solar radiation, ambient temperature, wind speed and direction, humidity, and many others. Since these meteorological factors are highly depending on the site-specific conditions, the routes of ballastless track in China has huge spread of territory and  their meteorological condition variation could have the significant effect on the mechanical behavior of the track-bridge system. China Railway Track System type  II (CRTS II)  slab track is one of typical ballastless track in high-speed railway. In order to guarantee the good structural performance of CRTS II track in long-term operation, it is necessary to study the influence of meteorological conditions on the thermal transfer effects of CRTS II track.

The meteorological parameters and the internal temperature in the track structure were collected for six months in Beijing-Shanghai high-speed railway as a case study,. The relationship between ambient temperature and temperature at the midspan and end of bridge are analyzed, and the relationship among four meteorological parameters (e.g. temperature, solar radiation, wind speed, humidity) were also investigated. The change of temperature within the track structure could obviously lags behind the change ambient temperature and their temperature variation are smaller than that of the ambient temperature. Furthermore, Pearson correlation analysis show that there is a strong positive correlation between the ambient temperature and the solar radiation with a Pearson correlation coefficient of 0.85, while the correlation coefficient between the ambient temperature and air humidity of 0.22 is the smallest.

the heat transfer models of CRTS II track were established based on finite element  software of Comsol. The total dimensions of five track slabs are 32 m length × 13.4 m width × 3.35m height, and the track slab, the CAM layer, and base plate are simulated by the solid elements. Two ends of the track slabs are constrained and the thermal responses of the track structure under the above four meteorological parameters were compared. The internal temperature and vertical displacement at the mid-span of the track slab become larger with the increase of the wind speed or solar radiation, especial for the wind speed exceed 6m/s or the solar radiation exceed 750 W/m². According to the 3D temperature field, the increase of the solar radiation or ambient temperature could lead to the rapid heat transfer process from the track slab to the base plate. The role of wind speed on the heat transfer effect in track structure is limited.