APPLICATION OF A DIRECT STIFFNESS METHOD TO WAVE-PROPAGATION IN MULTIPHASE POROELASTIC MEDIA

In this paper, it is demonstrated how a direct stiffness method for wa ve propagation in multilayered saturated poroelastic media, based on i ntegral transform techniques, can be modified to account for a small a mount of gas in the pores, Unsaturated media with small gas fractions can be treated using Smeulders' extension of Blot's poroelastic theory . The effect of the presence of gas bubbles on the fluid bulk modulus and the dispersion characteristics of a water-saturated sand of Mol is demonstrated. The direct stiffness method is illustrated with a numer ical example where transient wave propagation in a dry, saturated and unsaturated halfspace is considered.