Modeling of the FWD Deflection Basin to Evaluate Airport Pavements

Abstract

The falling weight deflectometer (FWD) testing develops a deflection basin on the pavement surface. Depths of this deflection basin from the center of the falling weight are measured at different radial offsets. These deflections are used for the backcalculation of the pavement layer moduli. Most of the available backcalculation software uses the layered elastic theory and static load to calculate moduli from known pavement surface deflections. However, the FWD test load is dynamic, and layer materials may show nonelastic behavior. Layered elastic theory in these types of software cannot characterize dynamic response of the pavement. Also, elastic theory is unable to accurately predict the surface deflection whenever stress developed in any pavement layer exceeds the yield point. For this reason, this study has performed a finite-element analysis of the airport pavement under the FWD test considering the dynamic load and materials plasticity. The analysis presented here includes elastoplastic behavior of pavement layer materials. Both axisymmetric and quarter cube models have been developed in