Liquid-saturated Porous Solids Research Articles

Surface waves in nonlocal transversely isotropic liquid-saturated porous solid

In this paper, propagation of surface waves in nonlocal transversely isotropic liquid-saturated porous solid half-space has been investigated. The model is proposed for two different situations of which one is for excluding fluid nonlocal effect, and the other is for including fluid nonlocal effect. The existence of a new wave that arises due to the presence of nonlocality parameter in the medium as well as some critical circular frequencies is derived. Dispersion equation for the propagation of Rayleigh-type surface waves and their conditions of existence at the free surface of transversely isotropic liquid-saturated porous solids has been obtained. The boundary may be opened surface pores or sealed surface pores. Dependence of the velocities of surface waves, Rayleigh wave type on the direction of propagation and frequency has been illustrated. These numerical results report the phenomena such as anomalous negative dispersion of wave velocities with frequency.

Incidence-angle-dependent acoustic reflections from liquid-saturated porous solids

SUMMARY Angle of incidence amplitude variations of acoustic waves reflected from an interface is increasingly important in acoustic sea floor imaging and seismological studies. Such observations are almost solely interpreted assuming elastic wave theory. However, wave propagation through, and hence reflectivity from, liquid-saturated porous solids is complicated by the presence of the slow longitudinal (P2) wave. There have only been limited quantitative experimental tests of porous media reflectivity as a function of angle of incidence. Here, the acoustic reflectivity from a water-saturated porous plate is measured as a function of the angle of incidence using a specially developed ultrasonic reflectometer. The observed reflectivity agrees with that predicted using the Biot-type poroelastic theory; this work confirms the use of boundary conditions that allow fluid transfer across the reflecting interface. It is found that simpler elastic expressions based on equivalent-elastic solid cannot be reconciled with the observations.

The influence of compressibility on the stresses of elastic porous solids—semimicroscopic investigations

In this paper the influence of the compressibility of the real material of the constituents of a porous medium on the stresses will be discussed for a simplified model of liquid-saturated porous solids. The basis of the model is the mixture theory restricted by the volume fraction condition (theory of porous media) . In comparison with the mixture theory, one additional constitutive relation for the so-called real part of the deformation of the solid phase will be formulated to close the system of equations for compressible binary porous media within the framework of the theory of porous media. The real deformation can be described by a second order tensor which results from the multiplicative decomposition of the deformation gradients of solid and liquid constituents.

The effect of uplift in liquid-saturated porous solids – Karl Terzaghi's contributions and recent findings

A recently discovered unpublished manuscript by Terzaghi is discussed extensively. It is revealed that this manuscript eliminates an insufficiency in the extant publications of Terzaghi. Moreover, Terzaghi's valuable contributions are compared with recent findings in the theory of porous media on the macroscale as well as on the microscale.

Wave propagation in anisotropic liquid-saturated porous solids

Biot’s theory is employed to study the propagation of plane-harmonic seismic waves in a transversely isotropic liquid-saturated porous solid. Along with SH wave, the existence of three quasiwaves is discussed and analytical expressions for their velocities of propagation have been obtained. It has been observed that velocities of existing waves vary with the direction of propagation. Frequency equation for the propagation of Rayleigh-type surface waves at the free surface of transversely isotropic liquid-saturated porous solids has been obtained. Possibilities of existence of body waves and surface waves have been discussed numerically by assuming different sets of values of elastic constants. Dependence of the velocities of propagation on the direction of propagation has been exhibited.

Propagation of elastic waves in a cylindrical bore in a liquidsaturated porous solid

SUMMARY The propagation of the elastic waves in a cylindrical bore through a liquid-saturated porous solid of infinite extent is discussed. The velocity dispersion equation appropriate to the surface wave propagation in a liquid-filled porous solid containing an empty bore is derived. The surface wave which is analogous to a Rayleigh wave at a plane boundary of liquid-saturated porous solid will be dispersive. The case of a liquid-filled bore is also discussed. Study of seismic waves is also concerned with the waves near cylindrical boreholes, since any measurement below the Earth's surface requires the drilling of a hole. Biot (1952) presented an analysis of the problem of propagation of elastic waves in a fluid-filled cylindrical bore hole in an elastic solid of infinite extent. The elastic solid considered was isotropic and homogeneous, and no account was taken of porosity, permeability and viscosity. Keeping in view the presence of porous solids, permeated by groundwater or oil in the Earth, the study of the problem of boreholes in liquid-saturated porous solids is more important. Biot (1956) established a systematic theory for the propagation of elastic waves in a porous solid containing a compressible viscous fluid. Constitutive equations and equations of motion for such solids were also formulated. We discuss here the probleni of propagation of elastic waves in a circular borehole through a liquid-saturated porous solid of infinite extent. Only harmonic waves with axial symmetry are considered here. The problem of propagation of surface waves is treated. Biot's (1952) results are obtained as special case of those presented here. The effects of presence of liquid in the borehole on the phase velocity are examined for a particular model.

Uplift, friction and capillarity: three fundamental effects for liquid-saturated porous solids : de Boer, R; Ehlers, W Int J Solids Struct V26, N1, 1990, P43–57

Uplift, friction and capillarity: three fundamental effects for liquid-saturated porous solids : de Boer, R; Ehlers, W Int J Solids Struct V26, N1, 1990, P43–57

Uplift, friction and capillarity: Three fundamental effects for liquid-saturated porous solids

In the present paper, the effects of uplift, friction and capillarity for liquid-saturated porous solids are discussed by use of general porous media theories (mixture theories extended by the volume fraction concept). Preceded by several historical remarks on former approaches to a.m. effects, the present investigation is based on a macroscopic binary model of incompressible constituents where, in the constitutive range, use is made of the second-grade character of general heterogeneous media. As a direct consequence of this procedure, the magnitudes of uplift, friction and capillarity effects are easily determined, thus solving an old problem in applied engineering.

Reflection and refraction of seismic waves incident obliquely at the boundary of a liquid-saturated porous solid

abstractA systematic theory of the propagation of seismic waves in liquid-saturated porous solids was first developed by Biot in 1956. Since then, some theoretical investigations have been carried out on the propagation of body and surface waves in such media. Further studies in this area may be useful in giving greater insight into the propagation of seismic waves in underground layers of porous solids saturated with oil or groundwater. In this connection, the transmission of normally incident seismic waves across the boundary of a liquid-saturated porous solid has been considered earlier. Keeping in view the fact that oblique incidence is more likely than normal incidence for such seismic waves, the authors have investigated the reflection and refraction of P and SV waves, which become obliquely incident at the boundary of a liquid-saturated porous solid, after propagating through an elastic solid. It is found that, corresponding to both P and SV waves obliquely incident at the boundary, there will be two refracted dilatational waves traveling with different velocities, which may be called the Pf and Ps waves, and one refracted SV wave, in the liquid-saturated porous solid, together with reflected P and SV waves in the elastic solid. The amplitude and energy ratios for the different reflected and refracted waves have been calculated theoretically. Numerical values of the amplitude and energy ratios have been computed for different angles of incidence for P and SV waves which propagate through granite, and then become incident at the boundary between the granite and oil-saturated sandstone, using results of laboratory experiments on the elastic behavior of oil-saturated sandstone. It is found that the amplitudes of the reflected and refracted waves depend significantly on the angle of incidence. It is also found that the amplitude of the second refracted P wave is usually much smaller than that of the other reflected and refracted P and SV waves, so that this slower refracted P wave will be difficult to detect. Similar amplitudes and energy ratios are also calculated for P and SV waves incident at the boundary between granite and dry sandstone. Comparison between the cases of dry sandstone and oil-saturated sandstone shows that the presence of oil usually has a significant effect on the amplitudes of the reflected and refracted P and SV waves.It is noted that such theoretical investigations may be useful in utilizing the amplitudes and other characteristics of reflected and refracted seismic waves in the detection and study of underground layers of porous solids saturated with oil or groundwater.