Rail rolling contact fatigue on a Chinese heavy haul line: Observations, monitoring and simulations

•Rail rolling contact fatigue on a Chinese heavy haul line was studied.•Significant influence of curves and train loads was identified during monitoring.•Cracks initiated in days and propagated quickly till a stabilized depth of 2.5 mm.•Crack depths measured by eddy current were verified by failure analyses.•A numerical approach for predictions of rail RCF occurrence is validated. Severe rail rolling contact fatigue (RCF) occurring on curves of a heavy haul line in China was studied by field observations, monitoring tests, failure analyses and numerical simulations. Visual appearance, worn profiles, surface hardness, crack dimensions and so on were measured in field for rails and typical running wheels, meanwhile other related information was also collected. Significant influences of the radius of curvature and loaded/empty trains were figured out. RCF cracks on R600 m curves was found to get initiated in days, propagated downward very quickly in the first 2 months, and then stabilized at a depth of about 2.5 mm until rail replacement owing to further propagation into un-flowed bulk material. Though the failure analyses, crack depths measured by an eddy current detector were verified. Considering measured/collected data, a numerical approach combining a train dynamic model and the damage function model (Tγ) has been developed to predict the rail RCF occurrence, in which the influence of trapped liquids was better modelled by introducing a critical angle of the resultant creep force. Typical simulations showed that numerical predictions could well explain the observed phenomena, providing a useful tool for further studies.