A permanent deformation model was proposed in this study for the use in numerical simulation of pavement materials under repeated loading. This model was modified from a conventional elastic-plastic model with linear strain hardening. It uses the secant modulus concept in simulating both loading and unloading material behavior in a permanent deformation test and takes into account the difference between the loading and unloading stress-strain curves by choosing different secant modulus values. Due to unloading secant modulus is usually larger than that of loading, permanent strain canbe predicted after each loading-unloading repetition. Since the secant modulus may be defined as a function of a set of influential variables, suchas the load repetition, stress level, temperature, moisture content, and other material properties and condition variables, the proposed model has potential to be used for different types of pavement materials in prediction of permanent deformation. One of the most important features for the proposed model is that all model parameters can be derived from a repeated permanent deformation test. In the second part of the paper, numerical simulation examples were presented with an implementation of the proposed model into a finite element program, ABAQUS. Simulation results checked reasonably well with both laboratory measurements and field accelerated pavement test results.
Abstract