Effect of Non-Homogeneity and Initial Stress on Torsional Surface Wave Propagation in Initially Stressed Poroelastic Medium Bounded by a Heterogeneous Layer and Half-Space

Since the layer of the Earth is non-homogeneous and initially stressed, this paper has framed to discuss propagation of torsional type surface wave in an initially stressed poroelastic medium sandwiched between a non-homogeneous layer with linear type variation in density and rigidity and a half-space of heterogeneous medium with exponential type variation in density and rigidity. Dispersion equation of this kind of wave has been obtained with the help of Whittaker's expansion and separation of variables method under some specified boundary conditions. The effect of non-homogeneity related with layer and half-space and initial stress of sandwiched medium have been illustrated based on their graphical discussion. It has been found that the presence of non-homogeneity in the material enhances the phase velocity but it also enhances the phase velocity with descending values of initial stress.