TY - JOUR TI - Air-coupled surface wave testing of pavements DO - https://doi.org/doi:10.7282/t3-y7r4-8323 PY - 2019 AB - One of the most important parameters in pavement evaluation is the elastic modulus. Significant efforts were put in the development and implementation of nondestructive testing (NDT) techniques for elastic modulus profiling of pavements. Spectral Analysis of Surface Waves (SASW) method is one of the successfully implemented methods. The method utilizes a phenomenon of dispersion of surface waves in layered systems. Once the dispersion curve, representing the surface wave velocity-frequency relationship, is measured, the elastic modulus profile is obtained through an inversion or backcalculation process. Traditional SASW test involves generation of surface wave by application of an impact on the pavement surface, and detection of the propagating waves by a series of sensors placed at various distances from the impact source on the pavement surface of the tested system. The non-contact or air-coupled SASW method is an extension of the traditional SASW method, where the leaky surface waves are detected using non-contact sensors, instead of the traditional contact sensors. The main objective of this study is to develop an automated system for pavement elastic modulus profiling based on air-coupled acoustic testing. To improve the speed and automate the modulus backcalculation process, an artificial neural network (ANN) based backcalculation of a pavement modulus profile was developed. Numerical simulations of the air-coupled SASW test using finite elements were used to develop training, testing and validation data sets. Several hundred finite element models of various pavement configurations were used to develop an extensive database of surface wave dispersion curves. The performance of developed ANN models was validated using both numerical and field test data. The validation using numerical data included backcalculation of profiles for synthetic pavement profiles not used in training and testing. The field validation was conducted using field test data collected by a built non-contact SASW testing system. The system was implemented on two pavement sections, which were also evaluated using ground penetrating radar (GPR) and the ultrasonic surface waves (USW) method to obtain pavement layer thickness and top layer modulus, respectively. KW - Air-coupled KW - Civil and Environmental Engineering KW - Pavements -- Elastic properties -- Testing LA - English ER -