Multi-factor analysis of temperature gradient and thermal effects in CRTS III slab ballastless track

The CRTS III slab ballastless track is widely applied in high-speed railway systems, which is crucially impacted by temperature gradients. This study establishes a comprehensive probabilistic model for temperature gradients that integrates nonlinearity, multi-scale time-dependency, and geographical variability. Thermal effect analysis is conducted based on different factors of the temperature gradient. Based on this model and historical meteorological data, a temperature gradient probability distribution dataset for 34 typical Chinese cities is developed using the Truncated Gaussian Mixture Model (TGMM). Furthermore, the influence of these factors on 12 critical structural responses is systematically quantified using a refined finite element model (FEM). Simplified linear gradients produce differences that depend on the response type when compared with nonlinear gradients. The mean absolute percentage errors of the 12 responses range from 2.42% to 100.41%. Service time also has a pronounced effect on the thermal responses. When the solar absorptivity a s increases from 0.4 to 0.8, the maximum downward vertical displacement of the composite slab under positive temperature gradients increases by 109.25%. The representative temperature gradients obtained for the 34 cities produce variations exceeding 100% in some structural responses. This result supports the use of design inputs adapted to local environmental conditions. This study provides a versatile model and dataset, offering a foundation for the precise design and life-cycle assessment of CRTS III track systems.