Numerical prediction of pavement distress with geotechnical constitutive laws

Abstract

The structural analysis and the selection of the performance models are the two most important steps in pavement performance analysis and they significantly affect the prediction of pavement distress. The nonlinear elasticity models which include the hyperelastic, hypoelastic, and k1-k5 models are used in this study. It shows that these three models can predict the behavior of the asphalt concrete and granular materials. These models are incorporated into the finite element program to predict the structural response of the pavement. The predicted displacements and stresses of the pavement by using these three constitutive laws agree well except for the tensile stress at the bottom of the asphalt concrete. The flexible boundary concept is used at the bottom of the finite element mesh to improve the finite element solution. The validation of the superposition principal for the nonlinear problem is studied. The results show that the errors due to superposition are acceptable, and the superposition is used in the 2-D axisymmetric finite element program to model the dual wheel loads. In the rutting model, the two parameters which characterize the relationship between the permanent strain and the number of load cycles are the plastic strain at the end of the first cycle of loading and the slope of log ε^D-logN curve. However, the plastic strain at the end of the first cycle of loading is based on the theory of the plasticity instead of an empirical equation. The microfracture and fracture mechanics approaches are used for the fatigue cracking model. The system identification method and pattern search scheme are used to calibrate the performance parameters so that the predictions of the pavement response can be improved. In the rutting model, the only calibration parameter is m in the creep compliance equation. The adjustment of m is based on the system identification method. For fatigue cracking, seven parameters are needed for calibration. The pattern search scheme is used to adjust these seven parameters. The calibrations are conducted for each climatic zone and they show that the predictions of the rutting and fatigue cracking agree with the field distress data.