Mechanical Properties of Slab Ballastless Track Subjected to Combined Effects of Loading and Temperature

Temperature has a significant impact on the structural performance of the China Railway Track System (CRTS) Ⅱ slab ballastless track-bridge and the structure is susceptible to fatigue damage under long-term loading. Therefore, it is crucial to conduct cyclic-loading test on the track-bridge structure to reveal the evolution of its mechanical properties under coupled temperature-load effect. In this study, a 1:4 scaled-down model of a ballastless track-bridge was produced and placed in a large-size environmental chamber for temperature-load coupled cyclic-loading tests. The results showed that after 1×10^6 cycles of loading, no cracks were observed on the surface of the track structure. The structural workability and load capacity of the track-bridge met the required service standards. During the temperature-load coupling test, the load-displacement curves of the structural system exhibited intervals, with a more significant increase in static-deflection values. The dynamic deflection of the structural system under the coupling action experienced a higher growth rate and more abrupt changes compared to single-load conditions. These observations indicated that the ambient temperature amplified the deflection of the structural system. The strain values in the track structure exhibited significant non-linearity, with temperature amplifying this effect. The dynamic-response test results revealed a negative correlation between the inherent frequency of the track structure and the ambient temperature, further emphasizing the influence of temperature on the stability of the track structure. Consequently, it is essential to enhance the monitoring of track structures in high-temperature climates to ensure their safe operation.