Characteristic analysis of wave propagation in anisotropic fluid-saturated porous media

In this investigation a characteristic analysis of stress wave propagation in anisotropic fluid-saturated porous media is performed based on generalized characteristic theory. This method enables us to carry out a complete basic analysis of wave propagation characteristic in fluid-saturated porous media, and immediately determine the wave fronts through the normal velocity surfaces. First, the characteristic differential equations and compatibility relations along bicharacteristics are deduced. Then the analytical expressions for the normal velocity surfaces and wave fronts are presented. Based on these equations, the characteristic of the normal velocity surfaces and the wave fronts for all components of the stress waves in an orthotropic fluid-saturated porous media as well as its special cases in three-dimensional space is computed and discussed. The results show that the wave fronts of fast and slow waves remain regular along with the increase of anisotropy of the media, but great anisotropy may lead to more than one triple angle on the wave fronts of quasi-transverse or transverse waves.