Accuracy and Resolution of Surface Wave Inversion

Shear wave velocity profiles of soils and pavements may be evaluated nondestructively using surface wave tests such as the Spectral Analysis of Surface Waves (SASW) method. In these tests, dispersion data are measured in situ and inverted using least squares techniques to obtain the shear wave velocity profile. This paper examines the influence of the number of dispersion points, the maximum wavelength, and the distribution of dispersion data with wavelength on the accuracy and resolution of the shear wave velocity profile. The results indicated that the best overall accuracy and resolution is obtained when the dispersion data is evenly distributed between the minimum and maximum wavelengths and the maximum wavelength is one to two times the maximum desired depth of the shear wave velocity profile. The number of points did not appear to significantly influence the inverted profile as long as the number of points remains greater than the number of layers in the inversion profile.