Calibration of Fatigue Cracking Model of Flexible Pavements Using Mechanistic-Empirical Based Probabilistic Method

Abstract

In order to utilize a mechanistic-empirical procedure in flexible pavement design, a procedure being able to predict the occurrence of the fatigue cracking of pavement in the field is needed. A mechanistic-empirical based probabilistic procedure was proposed for fatigue cracking modeling in this paper. The fatigue life of the pavement was assumed to be dependent upon the means of tensile strain at the bottom of asphalt layer, resilient modulus of asphalt layer, and applied traffic loading, as well as their variances. The damage ratio D was assumed to be a log-normal distribution and the percentage of area cracked was computed as the probability that log(D) exceeded zero. Taylor's expansion was employed to calculate the mean and variance of log(D) . The regression coefficients in fatigue cracking model were then determined by minimizing an objective function that represented the differences between the measured and predicted fatigue cracking areas. A procedure for converting categorical fatigue cracking ratings to numerical values was also proposed. The root mean squared error (RMSE) of the calibrated fatigue cracking model is about 7% (of the wheelpath area). The proposed procedure for the calibration of fatigue cracking model requires field and laboratory tests to verify its validity.