Investigation of Flexible Pavements' Edge Failure Distress
From practical observation, it was noted that failure near pavement edges is quite common in New Zealand. This failure mode is associated with the mountainous topography that makes constructing wide pavements expensive. The main objective of this research work is to investigate the different factors affecting this type of distress. A three-dimensional finite elements model was designed to study different loading and shoulder conditions. A half fractional factorial experimental design was developed to study five factors: shoulder width, shoulder stiffness, axle load, tire pressure and pavement thickness. The finite elements model solution was compared with multilayer analysis and actual field measurements carried out at the Transit New Zealand accelerated test track to ensure accurate predictions. None of the solutions provided a perfect match between the measured and predicted vertical strains. The multilayer linear elastic solution and the three-dimensional finite elements solutions were reasonably close. The order of importance of the different factors affecting pavement response in the outer wheel path relies on the type of response. Shoulder thickness was the most important factor affecting the maximum surface deflection under the outer wheel followed by axle load, tire pressure, and shoulder width. For the compressive strain on the top of the subgrade and the maximum shear strain in the base course, the order of importance of factors was different. The shoulder stiffness, width and thickness played a significant role in distributing the stresses and strains on the top of the subgrade, thus controlling the edge failure.