Backcalculation of pavement layers moduli using three-dimensional nonlinear explicit finite element analysis

A new backcalculation approach based on Three Dimensional Finite Element Modeling (3D FEM) was developed. This approach accounts for the transient dynamic nature of FWD load, the three dimensional geometry of the pavement structure, and the friction and bonding characteristics of pavement layers interfaces. The 3D FEM backcalculation approach was used to backcalculate the layers moduli of flexible, rigid, and composite pavement sites located in West Virginia. The layers moduli of each site were also evaluated using three widely used backcalculation algorithms: MODULUS, EVERCALC, and MODCOMP. Using 3D FEM backcalculation results as reference values, correction factors were developed for each program and pavement type.; The 3D FEM approach was also used to predict the apparent depth to bedrock. The decay of vertical stress and displacement in the subgrade layer were examined and used to predict the apparent depths to bedrock for four pavement sites located in Texas.; A parametric study was conducted to evaluate the effect of the subgrade layer thickness (assumed in the finite element pavement structural model) on the strew and deformation obtained on top of the subgrade layer and on the 3D FEM-generated deflection basin.; The effect of concrete slab length on the deflection basin was examined for both doweled and undoweled concrete slabs. (Abstract shortened by UMI.)...