A framework for inversion of wavefield spectra in seismic non-destructive testing of pavements

A method for the inversion of wavefield spectra in non-destructive testing of pavements is outlined. Data acquisition and processing is based on the Multichannel Analysis of Surface Waves (MASW) method. The inversion of a vertical-shear wave velocity profile is conducted on the full wave field spectrum using the Fast Simulated Annealing (FSA) algorithm. This procedure avoids dealing with discrete dispersion curves and mode identification for the inversion of surface wave data. The viscoelastic properties of the asphalt layer are included in the forward model, resulting in an inverted mastercurve, showing the asphalt stiffness as a function of frequency. The outlined approach is demonstrated on both synthetic and field data. The main benefit is that the raw field data can be automatically processed and inverted without any subjective user input, while properly accounting for the interference of different modes and types of waves. The main disadvantage at this point of development is an extensive (several hours) computational time for the inversion process. (Less)