Experimental and numerical study on interfacial thermal behaviour of CRTS II slab track under continuous high temperatures

•Continuous high temperature tests are conducted in a large temperature simulation test system.•The relationship between the stress and temperature in track slab presents quadratic polynomial equation.•The transient heat transfer models reflect interfacial thermal behaviours of the CRTS II track-bridge structure.•The axial force reaches 7086KN at the 108th hour under the higher continuous temperature from 45 °C to 36 °C.•The interface damage zones grow from two sides of the middle track slab to the central zone. The interfacial thermal behaviour of vertical multi-layer materials under high-temperature has a significant role in structural thermal behaviour of China Railway Track System (CRTS) II slab track in high-speed railway. In order to further clarify the interfacialthermal behaviour under continuous high diurnal temperature, a 1/4 large-scaled model of five CRTS II track slabs in a temperature simulation chamber was first tested to obtain their temperature distribution and stress responses. After the validation of experimental results, three-dimensional heat transfer models of the full-scale CRTS II track-bridge structure were then established to investigate their interfacial thermal behaviours under two continuous high diurnal temperature conditions, respectively. Results show that the transient heat transfer model could reflect thermal behaviours of the CRTS II slab track, and the relationship between the stresses and internal temperature in the track slab is a quadratic polynomial equation. There is no interface damage under a continuous high temperature from 35 °C to 26 °C with the largest vertical displacement of about 0.38 mm at the 108th hour. Under a higher continuous temperature from 45 °C to 36 °C, the largest vertical displacement increases to 1.24 mm. More importantly, the interface damage zones grow from both two sides of the mid-span track slab to the central zone with the upward arching shape.