Evaluation Index of CRTS III Prefabricated Slab Track Cracking Condition Based on Interval AHP

The cracking damage of the high-speed railway slab track seriously affects its durability and service life. The cracking condition index (CCI) for the China railway track system (CRTS) III prefabricated slab track and the corresponding calculation methods were proposed to realize the scientific management and guide the maintenance more reasonably. In order to ensure the objectivity and rationality of each parameter's weight, first, the finite-element (FE) model of CRTS III prefabricated slab track with surface cracks was established to analyze the crack growth behavior, based on the fracture mechanics theory. The results show that the crack growth rate of transverse cracks at the same depth is greater than that of longitudinal cracks and significantly greater than that of through cracks. Then 437 valid questionnaires were obtained through expert consultation. Combining the subjective factors of expert evaluation with the objective factors of numerical simulation, the Delphi method and interval analytic hierarchy process (AHP) were used to establish the structural hierarchy, which could determine the weight of each parameter. After that, it was applied to an engineering example. The results show that the weights obtained by the comprehensive method combining the Delphi method and the interval AHP are more objective. Furthermore, the evaluation method was applied to the engineering example, obtaining the slab track CCI within [70.91, 72.83] points, which verified the rationality of the evaluation method. In short, the index evaluation method can quantitatively analyze the cracking severity of the track slab, which has important reference and practical value for line maintenance.