LAUSR

Abstract With the development and application of highway-speed nondestructive testing (NDT) devices, a reliable method to evaluate the current level of deterioration of pavements from the measured results is necessary to provide comprehensive and timely maintenance and rehabilitation decisions for pavements. The objective of this study is to evaluate the deterioration conditions of flexible pavements from their deflection profiles under the moving loads. The deterioration is due primarily to the development and growth of microcracks in flexible pavement materials and is commonly called the “crack initiation” phase. This phase is characterized and represented by changes in the dynamic modulus and the phase angle. To simulate a flexible pavement under moving loads, a three-dimensional (3D) finite element (FE) model and its equivalent two-dimensional (2D) axisymmetric FE model are constructed using a commercial FE software and the technique of artificial intelligence (AI). The deflection profiles of the pavement model are analyzed and the time lag between the load and deflection peaks is used to define a new term named “lag angle” to represent the structural response of the flexible pavement under the moving loads. It is also found the lag angle is closely related to the degree of deterioration of the pavement, the speed of the moving load, the structural and material properties of the pavement, which reveals a promising application of the lag angle in the evaluation of flexible pavements using highway-speed NDT devices.