Review of modelling crack initiation and propagation in flexible pavements using the finite element method

Abstract

Cracking is a major failure mechanism that directly affects the functionality and performance of flexible pavements. The objective of this study is to present the state of knowledge on the use of finite element method (FEM) including cohesive zone model (CZM) to simulate cracking failure mechanisms in flexible pavements under field conditions. Based on this review, a knowledge base is established on how FEM can be effectively applied to predict pavement performance against cracking failure mechanisms. Two main approaches are presented in this study. In the first approach, focused finite element (FE) meshes are used to simulate the crack initiation and propagation phases. Focused meshes allow for estimating the J-integral and the stress intensity factor (SIF) through different contour lines. Since the SIF is a measure of the stress and strain environment around the crack tip (a greater SIF indicates a faster rate of propagation), the rate of crack propagation per cycle can be estimated based on empirical equations such as Paris’ Law. In the second approach, the propagation of damage is simulated using FE and CZM. This approach allows one to study the loading mechanisms responsible for progressing cracking damage in the pavement structure. In summary, both approaches have merits in modelling cracking in flexible pavements. While focused meshes may be used to predict the number of cycles for crack propagation, CZM may be used to study the controlling stresses and mechanisms responsible for crack propagation.