| Development of non-destructive and high performance testing methods has been requested for the pavement assessment. While FWD (Falling Weight Deflectometer) has been widely utilized as such NDT equipment in Japan, the inversion process of FWD is still ambiguous. Dynamic response of the surface pavement is simplified to static torsional deformation. In contrast, high-frequency surface wave measurements are capable to provide detailed information on the pavement. The authors have started a research project on non-contact, continuous surface wave measurement using arrayed microphone. At the initial phase, we conducted fundamental measurements using piezoelectric accelerometer array (Inazaki, 2003). A total of 48 accelerometers were pasted on the pavement surface with clay pad at 10 cm intervals. Observed data showed clear dispersion in the frequency range from 40 to 5000Hz, and analyzed as A0 mode Lamb waves or normal mode surface waves using a generic algorithm (GA) technique (Hayashi, 2012). Parameter study was conducted on the surface pavement structure to the responses of dispersion curves of surface waves. Combined with parameter sturdy, GA inversion successfully reconstructed surface pavement Vs structure. The estimated structure was verified by comparative measurement using double frequency (300 and 800 MHz) antenna system GPR as well as check drilling. |
