Analyzing the Effect of Axle Loads on Pavement Layers using the Mechanistic-Empirical Method

Abstract

One of the most important infrastructures for any country is the road system. The main cause of the accelerated deterioration of flexible pavement on Iraqi roads is overloaded vehicles, which can lead to the failure of asphalt roads. As a result, two types of asphalt road failure that need to be taken seriously are fatigue and rutting. The study's objective is to use the Mechanistic-Empirical Method (M-E) to identify fatigue and rutting failures by employing (KENLAYER) program to analyze flexible pavement performance at different axle loading. Assuming that the pavement structures form a linear multi-layer structure for flexible pavement, and that their mechanical responses depend on temperature and loading, HMA layers behave as viscoelastic materials in real-world settings, and the granular layers behave as nonlinear materials. According to Iraqi axial load requirements, the axle load were applied at proportions of 50%, 100%, 150%, and 200% of the Iraqi standard. The findings showed that the asphalt stabilized base course of the single axle experienced the highest tensile strain values among the layers (1.5*10-4) for the standard load, while the top of the subbase layer of the single axle with dual tires experienced the highest compressive strain values (4.761*10-4) for the standard load. It was also observed that the increasing of axle loads produces an increase in the vertical displacement of the pavement. Where the deformation value on the wearing layer of the tandem axle is (0.8998 mm) for standard load, and that 74% of this deformation was in the subgrade layer. The asphalt stabilized base course had the highest damage ratio with a value of (0.04426) at standard load. Additionally, it was revealed that increasing the load twice the standard load results in a 9 times reduction in design life, which lowers paving efficiency.