Dispersion characteristics of Love wave in unsaturated layered porous media

Key words:  Love wave  unsaturated porous media  dispersion characteristics  connectivity factor  sensitivity analysis

Abstract:

Using connectivity factor to handle the boundary condition between the two upper layers, the Love wave dispersion equation for three layers in an unsaturated porous media was derived based on the constitutive relations, and then the multi-mode Love wave dispersion curves were calculated numerically. The results indicate that, for the second or higher order Love wave modes, the higher the mode order, the larger the cut off frequency, in contrary to the fundamental mode Love wave which doesn 't have cutoff frequency. The maximum velocity of Love waves for all the modes asymptotically reaches the shear wave velocity of the half-space, while the minimum velocity reaches the shear wave velocity in the top layer. The Love wave velocity curves for all the modes are separated by, but are also linked to the shear wave velocity in the second layer. The smoothness of the velocity curves is controlled by the mode number:the higher the mode, the better the smoothness. Analyses show that the sensitivity of Love wave phase velocity to different parameters decreases with the order of the following parameters: porosity, saturation, connectivity factor, viscous coefficient and permeability.