Calibration/Validation of the Rutting Model in the Texas Mechanistic-Empirical Flexible Pavement Design Method




Masad, Ahmad

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This thesis presents a practical approach for calibrating and validating the rutting model of the mechanistic-empirical flexible pavement design model developed for the Texas DOT (TxME). The rutting calibration coefficients were established for each of the pavement layers by minimizing the sum of the squared errors (SSE) between observed surface (i.e., total) rutting and estimated pavement layer plastic deformation. The Texas flexible pavement data storage system (DSS) database was used exclusively for the calibration/validation analysis. A total of seventy-seven (77) different pavement sections in Texas state were selected and grouped by pavement type (i.e., new construction, overlays and perpetual) and base type (i.e., unbound, cement stabilized/unbound and binder or lime stabilized/unbound). These sections were splitted into two data subsets. Roughly/Randomly, 85% were selected for calibration while the other 15% were selected for validation. The project focus was intensified to achieve the two main objectives associated with the calibration, minimize bias (i.e., minimize the differences between distress predictions and observations) and maximize quality of fit (i.e., minimize the squared differences between distress predictions and observations). The error minimization was performed by using the Excel® Solver. The quality of fit was assisted by the goodness of fit statistics. The results of this project showed that the calibration of the TxME rutting model resulted in a reduction in bias by a factor of five and a reduction in SSE by 70%.


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Calibration, Mechanistic Design, Rutting, Validation



Civil and Environmental Engineering