Three-dimensional pavement analysis with nonlinear subgrade materials

The nonlinear models of pavement base and subgrade were briefly reviewed. Subroutines of the three-dimensional finiteelement analysis in the ABAQUS package were developed for nonlinear behavior of a coarse-grained base and subgrade. The programs were validated by comparing them with the theoretical-solution-based program BISAR and the 2D finite-element program ILLI-PAVE. Significant discrepancy was found between the 3D analysis and the 2D axisymmetric analysis, especially for the deformation results. It was also found that the stiffness matrices of the nonlinear materials were not symmetrical, which causes accuracy problems in those programs based on 2D axisymmetry formulations. The results of nonlinear analysis and linear analysis were also compared. It was concluded that the determinations of the resilient modulus for the linear models is critical to interpret the behaviors of nonlinear materials.