Comparison of Critical Responses of Pavements Obtained from Nonlinear Analysis Using Multilayered Theory and Finite Element Method

There are several methods for analyzing flexible pavements, where the most widely used of which are the multilayerd theory and finite element method (FEM). In this study, two sections of four-layered pavement with assuming two temperatures for surface layer (25 and 40 °C) were analysed and five responses at radial distances obtained from nonlinear analysis using two methods of multilayered theory and finite element method were compared. NonPAS program is employed for nonlinear analysis of these two sections based on the multilayered theory and MICHPAVE program is used for nonlinear analysis of these two sections based on the finite element method. Also, 7 different methods have been used to determine stress points and correct stresses in the multilayered theory method. The results of the analysis showed that only for the vertical stress response on the subgrade, the results of the two programs are very different and for other responses, the difference between the two programs is reasonable. It was also found that the responses obtained from the NonPAS program for a thicker section were in better agreement with the results obtained from the MICHPAVE program. Among the 7 methods considered for determining the stress points in the multilayered method, method 7, which is based on sublayering the nonlinear layer and considering the stress points in the central depth of the sublayers and modifying the radial stresses based on the maximum tensile strength of the materials according to Mohre's failure criterion showed best conformity with the results of MICHPAVE program.