Validation of a three-dimensional finite element model using airfield pavement multiple wheel load responses

Various highway vehicle axle/wheel arrangements and aircraft gear configurations adopted nowadays to accommodate increasing load levels impact flexible pavement response and performance in accordance with different multiple wheel loading scenarios. As the demand for heavier wheel loads and number of load applications continually increases, it is essential to properly characterize the nonlinear behavior of the pavement subgrade and unbound aggregate base/subbase layers. This paper focuses on the validation of a recently developed three-dimensional (3D) nonlinear finite element (FE) model using the measured responses of airfield flexible pavement test sections trafficked under 4-wheel and 6-wheel aircraft gear configurations. For this purpose, realistic nonlinear, stress-dependent pavement subgrade and base/subbase resilient modulus models were employed in a programmed User MATerial (UMAT) subroutine of the general purpose ABAQUS™ FE program. The predicted pavement responses matched closely with the displacements and stresses measured in the field and the FE model could be reasonably applied to the design of airfield pavements serving multiple wheel gear loads when the nonlinear pavement geomaterials were considered. In addition, comparisons made between the single wheel superposition and the full 3D loading results proved the need and Importance of 3D FE nonlinear analyses of thinly surfaced flexible pavements to properly consider both the stress dependent modulus behavior and the implications of multiple wheel loads and their interaction.