Anisotropy induced dispersion behaviors of Rayleigh waves

Surface wave analysis is sometimes used in engineering investigations to obtain ground stiffness profiles by inversed modeling of dispersion velocities. Since dispersion data may be polarized due to material anisotropy, a thorough understanding of the dispersion property is necessary for the accurate reconstruction of inversion models. Based on the general constitutive relation of stress and strains, the implicit relationship between the phase velocity and azimuthal angle was derived. Results from numerical modeling demonstrated that material anisotropy could produce dispersion behavior of surface waves. In a material with transverse isotropy, how the phase velocity varies with depth depends on the azimuthal angle. In particular, the phase velocity attends a maximum value at an azimuthal angle 45 and shows dispersive at large azimuthal angle.