To reveal the shielding effect and spatiotemporal distribution characteristics of the temperature field of the ballastless track in the transition section of high-speed railway bridges and tunnels under sunlight radiation, a sunlight radiation model for the transition section of the ballastless track was established based on the three-dimensional heat flow solid coupling method of sunlight radiation atmospheric environment ballastless track and its lower foundation. The real-time dynamic recognition of sunshine and shadow was realized, and the effectiveness of the model was verified by field measurement. The results show that the three-dimensional temperature field of the slab track in the transition section can be precisely solved using the 3D thermal-fluid-structural multi-field coupling method. Under sunshine radiation, the longitudinal temperature difference of the slab track in the transition section along the line reaches 25.26 ℃, and the shielding effect is significant within 16 m from the tunnel entrance. With the increase of tunnel depth, the temperature change of the slab track in the transition section slows down, and the temperature of the slab track is stable when it is more than 44 m away from the tunnel entrance. In a day, the peak value of the longitudinal temperature gradient of the slab track increases first and then decreases, reaching the maximum of 4.82 ℃/m at 14: 00. The temperature fluctuation amplitude of the slab track in bridge tunnel transition section is large and the longitudinal fluctuation range is small, so it is recommended to use subsection function to fit the longitudinal temperature distribution. © 2024 Huazhong University of Science and Technology. All rights reserved.
