Rutting performance prediction of flexible airfield pavements using nonlinear mechanistic models for asphalt and granular layers

• Uses viscoelastic-viscoplastic model for asphalt and plasticity with evolving hardening for the underlying layers. • The model is capable of predicting the laboratory tests and airfield test sections tested at FAA. • PANDA-AP enhances traditional tools like FAARFIELD for simulating rutting under complex loading and environmental conditions. • Accounts for cumulative deformation across asphalt and granular layers. The rutting performance of flexible airfield pavements is simulated by incorporating the permanent deformation of asphalt and granular layers. To achieve accurate predictions, airfield pavements are treated as a unified system, where the total rutting is the cumulative sum of the permanent deformation contributions from each layer. A nonlinear viscoelastic-viscoplastic model is employed to simulate the response of the asphalt concrete layer, accounting for its time-dependent and plastic behavior. For the granular layers, a modified Drucker-Prager non-associative plasticity model with evolving hardening is utilized. The evolving hardening function captures the microstructural changes in granular materials under cyclic loading, enabling the model to represent the progressive increase in permanent deformation with repeated load applications. These advanced constitutive models are implemented in the standalone PANDA-AP software (Pavement Analysis using Nonlinear Damage Approach: Airfield Pavements), specifically designed to predict the performance of airfield pavements. PANDA-AP is used to simulate the response of Construction Cycle 3 (CC3) test sections evaluated at the National Airfield Pavement Test Facility (NAPTF). Results demonstrate that PANDA-AP effectively predicts both the overall rutting and the layer-specific rutting behavior. Finally, comparisons are presented between simulations conducted using PANDA-AP and those performed with FAARFIELD software, highlighting the capabilities and differences of these modeling approaches.