Temperature field and thermal effect analysis of CRTS III ballastless track structure under the outdoor natural environment

•Temperature field test on CRTS III ballastless track structure for high-speed railway is conducted.•The unified method of thermal–mechanical coupling analysis of CRTS III under the outdoor natural environment is proposed.•Time-dependent temperature field, the cooperative performance of track structure and the mechanism of interface damage and separation are revealed. In this work, the full-scale temperature field tests on the CRTS III ballastless track structure have been implemented to investigate the temperature characteristic of CRTS III under natural environment. The unified and practical temperature field analysis method and its effect on the CRTS III track structure under the outdoor natural environment are developed based on meteorology, heat transfer, and radiation theory. The time-dependent temperature field of CRTS III, the spatial geometry of the structure under different interlayer connections, and the interfacial behavior are conducted by the proposed method. It is found that the temperature field of the track structure changes periodically – following and time-lagging effect with time. Under thermal load, the track structure presents the spatial shape of a “four corner warpage”, the non-uniformity of structural deformation will induce interlayer damage and affect the overall performance of the structure. Moreover, the critical interface strength at which damage occurs is 0.43 MPa, the interfacial damage begins near the limit structure and the slab end under the action of temperature. Besides, after interlayer failure, the connecting reinforcement can effectively restrain the relative displacement between the layers and ensure the coordinated deformation of the composite slab, whereas it leads to the deformation of structure increasing due to additional internal force.