Numerical Simulation of Pavement Life Deterioration: Tree-Roots’ Effects

Flexible pavement is usually designed to last for at least 20 years, however sometimes the first failure is formed after the first year of use. This failure has been associated with; overloading of the structure, use of poor materials, drainage problem and inadequate pavement thickness, and poor compaction; without considering presence of tree-root in pavement layers. However, with the numerous advantages of finite element model (FEM) in designing pavement structure and coupled with the fact that it’s a non-destructive tool, it makes its use sustainable. Therefore, this study focuses on investigating the impact of tree-roots on design life of flexible pavement using FEM. Results of the study show that tree-roots within any layer, and most especially within the subgrade layer, have a great effect on its bearing capacity. Moreover, it was found that this effect decreases subgrade life by approximately 13 - 67 %, with respect to the root thickness and this consequently decreases the entire pavement life.