Rutting prediction in airport pavement granular base/subbase: A stress history based approach

Test data from full-scale aircraft gear loading conducted at the National Airport Pavement Test Facility (NAPTF) by the US Federal Aviation Administration (FAA) were analyzed to investigate the effects of wander (offset loads) and channelized traffic loadings on the deformation behavior of unbound aggregate layers in asphalt pavement test sections. Insights were drawn on the complex rebound (recovered) and residual (unrecovered) deformation trends of granular materials due to passing of each of the 6-wheel Boeing 777 (B777) and the 4-wheel Boeing 747 (B747) gears for various combinations of loading (stress history effects), wander positions, and wander sequences. Measured field layer deformations and the accumulation rates could only be achieved when the magnitudes and variations of stress states in the granular layers, number of load applications, gear load wander patterns, previous loading stress history effects, trafficking speed or loading rate effects, and finally, principal stress rotation effects due to moving wheel loads were properly accounted for. Accordingly, measured transverse profiles and multi-depth deflectometer data were used to create individual pass residual deformation transverse profiles. The created transverse profiles were then combined with stress history effects to predict the residual transverse profiles for the test sections with P209/P154 granular base/subbase layers. The proposed method emphasizes the use of the previous load location and stress history of the pavement element to develop the residual deformation in that element. Calculation of the residual deformation in each element across the pavement surface results in the development of the complete permanent deformation transverse profile. This technique can be applied to estimate the transverse rutting profile of the pavement after trafficking based on any combination of applied wander and traffic direction.