Development of a mechanistic-empirical model to characterize rutting in flexible pavements

Dramatic increases in the number and weight of vehicles have resulted in severe rutting on highways in Taiwan. The Taiwan Area National Freeway Bureau constructed an in-service test road in 1996 to investigate the effect of pavement structures and paving materials on pavement performance. A mechanistic-empirical rutting model was developed to account for material property changes in the progression of rutting over time and the cumulated compressive plastic strains of all layers on the basis of traffic loading. In addition, a three-dimensional, dynamic finite-element simulation was established to calculate pavement responses that were input into the rutting model for predicting permanent deformation. Traffic speed showed significant impact on vertical strains at the top of the surface layer, and its influence was consistent with those measured by other researchers. The rutting parameters in the model were calibrated using rut depths obtained from the field test, and the validation outcome showed that their predictions were in good agreement with measured ones. The results of this paper demonstrate that incorporating the mechanistic-empirical approach in the prediction of rutting is viable and provides valuable information on the contribution of each layer to permanent deformation in flexible pavements.