Gas-saturated Porous Media Research Articles

Space-angular distribution of seismoacoustic waves excited by a vibration source in a semibounded gas-saturated porous medium

Specifying the formulation of the problem, let us note that as a fluid that fills the pores we consider air whose density is known to be several orders lower than that of the frame material, but whose acoustic velocity is higher than the velocity of compression wave propagation in the frame. Therefore, we speak of soil whose granules contact each other at several points, and in view of the reduced rigidity in the contact region compared with the rigidity of the forming continuous material, the effective compressibility of such a medium becomes rather significant and the velocity of longitudinal waves can drop below an acoustic velocity in air, which is confirmed experimentally for geologic materials deposited at depths from 1 to 1.Sin or higher [6]. Below we consider a gas-saturated two-phase medium that fills the lower halfspace the plane free boundary of which is subjected to the vertically oriented oscillating force P exp(-/~t), which is uniformly distributed across a circular platform with radius a. In this case, using the known methods, we calculate the radiation field of all types of elastic waves, in particular, P waves of the first and second kinds and S waves. For the case of a P wave of the first kind, it is easier to calculate the amplitude and phase dependences of radiated fields for the Fra~mhofer region, using the known asymptotic methods. In essence, the fmding of the field structure is reduced to estimating the integral expressions used to describe the field in the sector of angles that are adjacent to the direction of the main ray plotted according to the rules of geometric optics to connect the source and the observation point. In view of the wide use of the above methods (we speak of the method of the standard integral and the method of the stationary phase), including integral calculation on their basis, we mention [5, 7], in which they are described in detail. Calculating as in [5, 7] and using

Elastic coefficients for liquuid- and gas-saturated porous media : X. Li, International Journal of Engineering Science, 32(2), 1994, pp 195–208

Elastic coefficients for liquuid- and gas-saturated porous media : X. Li, International Journal of Engineering Science, 32(2), 1994, pp 195–208

Elastic coefficients for liquid- and gas-saturated porous media

The isothermal elastic behavior of porous media containing both gas and liquid phases is investigated theoretically and special attention is paid to the determination of the elastic coefficients involved. Considering the solid, liquid and gas as individual continuous phases, the constitutive equations are proposed in such a way that they satisfy the thermodynamic restrictions which are established, on the other hand, within the framework of the theory of mixtures. It is demonstrated that a new effective stress concept should be introduced to deal, in a generalized manner, with the multicomponent fluid-saturated porous media. It is also verified theoretically that there exist two independent stress state variables for the three-phase media, in contrast to the one variable for the two-phase ones. In a linear version of the general model, it is shown that the mechanical response of the media depends on the conventionally defined elastic properties like Biot's constants and two other parameters that describe the capillary effect associated with the deformation of the media. A compressible gas model, as a special application example of the general model, is used to illustrate the influence of capillary effect on the elastic constants.

Jump conditions across strong compaction waves in gas saturated rigid porous media

Based on experimental results and some additional simplifying assumptions, the general macroscopic two-phase equations governing the flow field which is developed in a gas-saturated rigid porous medium domain were simplified to a form which enabled us to develop two analytical models for calculating the jump conditions across a strong compaction wave. Predictions obtained by these two simplified analytical models are compared to the experimental results of Sandusky and Liddiard (1985) and to predictions of another more complicated model which was proposed by Powers et al. (1989). Fairly good to excellent agreements are evident.

Variable-pressure capillary impregnation of a gassaturated porous medium

Variable-pressure impregnation of a gas-saturated porous medium differs considerably from the constant-pressure case. The periodic pressure falls and rises have marked effects on the gas content. Pressure cycling can increase the extent to which the gas is displaced.

Axisymmetric stress state near a cylindrical working in a gas-saturated mass with nonsteady gas filtration

The authors study the stress state and strength of a gas-saturated mass near a cylindrical working with nonsteady gas filtration and hydrostatic rock pressure. An analysis is made of the effect of the form of the working on the stress state and strength of the mass and a conclusion is made on the possible orientation of the rockburst. The problem of the stress-strain state of a gas-saturated mass is described by coupled equations of strain of a gas-saturated porous medium and gas filtration.

Strain in gas-saturated porous media

Strain in gas-saturated porous media