Mechanistic-Empirical Model to Characterize Rutting in Unpaved Road with a Shallowly Buried SRHDPE Pipe

The Mechanistic-Empirical road design guide has been more and more used in the road design to consider the long-term performance of the road. In some road sections, there is pipe buried in the road for the sake of drainage. To investigate the effects of the shallowly-buried pipe on the permanent deformation of road surface under cyclic traffic loading, one laboratory test of an unpaved road with buried Steel-reinforced high-density polyethylene (SRHDPE) pipe under cyclic loading was conducted. In the tests, a 61-cm diameter SRHDPE pipe was buried in a compacted sand trench covered by AB-3 and sands. A Mechanistic-Empirical model was calibrated with the laboratory test data and adopted to predict the permanent deformations of the road under cyclic loading. It was found that the M-E model could simulate the road permanent deformation well under cycling loading before the road failed. Parametric study shows that pipe stiffness had considerable effects on the road deformation under cyclic traffic loading.