Finite element modeling and parametric analysis of viscoelastic and nonlinear pavement responses under dynamic FWD loading

Falling Weight Deflectometer (FWD) is the common non-destructive testing method for in-situ evaluation of pavement condition. This paper aims to develop finite element (FE) models that can simulate FWD loading on pavement system and capture the complexity in material properties, layer interface, and boundary conditions. Parametric analysis was conducted considering the effects of dynamic analysis, temperature gradient, bedrock depth, asphalt layer delamination, viscoelasticity, and unbound material nonlinearity on pavement surface deflections and critical strain responses. Although the parametric analysis findings vary depending on the specific pavement response, the study results illustrate the appropriate selection of analysis type, constitutive models of pavement material, and layer boundary conditions on the accuracy of FE modeling results. In particular, the analysis findings show that delamination in asphalt layers induces the greater strain responses; while neglecting bedrock effect overestimates surface deflections. The developed FE models can directly benefit the use of FWD testing for in-situ pavement condition evaluation, such as pavement performance prediction and/or backcalculation of layer moduli.