221-230In recent years
pavement maintenance planning has become a main task among highway agencies. In
order to determine the structural capacity of a flexible pavement,
non-destructive testing equipment is used. Many countries use the falling
weight deflectometer (FWD). It is possible to obtain deflection data and
backcalculate the pavements’ mechanical properties. However, the method used
affects the backcalculated values. A user-friendly finite element code has been
developed in order to backcalculate pavement properties. The problem in using
any finite element program is to prepare mesh data. In order to facilitate the
mesh preparation, a mesh generator have been developed. The constitutive
equations for the bituminous mixture are visco-elastic, linear elastic,
visco-elasto-plastic; for granular layers non-linear elastic (K-q Model, Boyce Model, Pappin Model, Elhannani Model) and linear
elastic, while for the subgrade non-linear elastic and linear elastic are used.
Considerable deflection data are analyzed during the study using different
models. The results indicate that the back-calculated properties depend upon
the model which has been used. Therefore, using simple models can cause either
over-design or under-design problems. The program is then tested against other
back-calculation programs. The results indicate that the proposed program is
better than other existing programs