Rayleigh waves in anisotropic porous media

Abstract

Rayleigh waves represent waves propagating in a half-space and attenuating exponentially with depth. During the last 30 years considerable progress has been achieved in developing both analytical and numerical methods for analysis of Rayleigh waves propagating in homogeneous media with arbitrary elastic anisotropy. The propagation of Rayleigh waves in heterogeneous media has not been studied nearly as often. Very few works are devoted to the analysis of speed and attenuation of Rayleigh waves in media (mainly isotropic) with uniformly distributed pores and/or microcracks. The advantage of applying Rayleigh waves to the nondestructive determination of concentration and the preferred orientation of pores lies in its high sensitivity to variation of the material elastic parameters due to preexisting pores. The developed approach for analysis of Rayleigh waves in porous or cracky anisotropic media is based on a combination of six- and three-dimensional complex formalism and the two-scale asymptotic analysis. In its turn, the latter utilizes a newly developed spatially periodic boundary integral equation method. This is used for determination of the effective characteristics of heterogeneous media containing isolated uniformly distributed pores. Numerical data are discussed.