Abstract:

This paper involves a discussion about the expressions of density parameters of the Biot medium. Firstly, it gives the field equations of seismic wave propagation in the Biot medium. Secondly, it defines the differential density by the difference between two densities of the Biot medium under open-pore and close-pore conditions, and these densities are derived from the kinetic energy equations. This differential density emphasizes the average macroscopical state of porous media and avoids the details about the pore shape. Lastly, the expressions of density parameters of the Biot medium in terms of the differential density are presented in this paper. The discussion about these expressions that deepens the understanding of these densities especially points out that the negative feature of the coupling density is the result of the restriction between the negative feature of the kinetic energy and the equilibrium of inertial forces.

Key words: Biot medium, density parameter, differential density, coupling density