Optimizing Non-linear Granular Layer Coefficients of a Flexible Pavement for Mechanistic-Empirical Method

In recent years, mechanistic-empirical (M-E) design methods are preferred in the design of flexible pavements instead of empirical methods using equations based on the road performance tests. However, the calibration of transfer equations that convert mechanical responses to pavement life and the definition of layer materials used in M-E methods have great importance for M-E methods. In this study, mechanical analyses of a cross-section designed with the AASHTO-93 method were performed, and service life values were calculated with different empirical transfer equations. The obtained M-E design results were compared with the results calculated with the AASHTO-93 method, and transfer equations compatible with the AASHTO-93 method were determined. Among the transfer equations examined, it was found that the rutting equation of the Asphalt Institute gave the most consistent results with the AASHTO-93 method. In the mechanical analysis of the selected cross-section, granular base and sub-base layers were defined as non-linear elastic reflecting the actual in-situ conditions. K-Ɵ model was preferred for non-linear elastic layer definition, and K1 and K2 parameters of this model were optimized.