Inversion of Air-Coupled Surface Wave Pavement Testing Data Based on Individual Receiver Spacing Approach

Air-coupled SASW (spectral analysis of surface wave) testing is a seismic technique for in situ evaluation of elastic moduli and layer thickness of layered systems, such as pavements and soils. It is an improvement over the conventional SASW testing with ground-coupled sensors in a way that leaky surface waves are detected by noncontact (i.e. air-coupled or microphones) sensors. Commonly, the average of the dispersion curves for different receiver spacings is used in the inversion process. However, there may be significant differences in the dispersion curves for a different spacing due to the interference of a number of body and surface waves radiated from the surface, and even direct acoustic waves. This study presents an inversion procedure for the air-coupled SASW testing on asphalt concrete (AC) pavements based on an individual receiver spacing approach. The inversion process itself is done using artificial neural networks (ANNs). The ANNs were trained by using several hundred synthetic dispersion curves for different receiver spacings developed from the numerical simulation of air-coupled SASW test. The inversion results of the recently developed ANNs models were compared with the models developed based on the average dispersion curves. The results point to significant improvements in the pavement modulus profile prediction.



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