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Reflection and Transmission of Elastic Waves from the Interface of a Fluid-saturated Porous Solid and a Double Porosity Solid 总被引:1,自引:0,他引:1
The reflection and transmission characteristics of an incident plane P1 wave from the interface of a fluid-saturated single porous solid and a fluid-saturated double porosity solid are investigated.
The fluid-saturated porous solid is modeled with the classic Biot’s theory and the double porosity medium is described by
an extended Biot’s theory. In a double-porosity model with dual-permeability there exist three compressional waves and a shear
wave. The effects of the incident angle and frequency on amplitude ratios of the reflected and transmitted waves to the incident
wave are discussed. Two boundary conditions are discussed in detail: (a) Open-pore boundary and (b) Sealed-pore boundary.
Numerical results reveal that the characteristics of the reflection and transmission coefficients to the incident angle and
the frequency are quite different for the two cases of boundary conditions. Properties of the bulk waves existing in the fluid-saturated
porous solid and the double porosity medium are also studied. 相似文献
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Energy focusing is found on the wave fronts of slow waves, which is a new propagation characteristic for slow waves in fluid-saturated
porous materials. The material parameters, as well as the propagation directions, are chosen as the control parameters. Combined
with the two axial variables, the influence of the anisotropy of the solid skeleton and pore fluid parameters on the propagation
characteristic of slow waves in anisotropic fluid-saturated porous materials is discussed. The correspondence between the
focusing on the wave fronts and the contours of zero Gaussian curvature on the slowness surface is explored. The development
of the focusing patterns is investigated and the distinct trends in the energy flux focusing structures are revealed. This
is helpful in further understanding the roles of the pore fluid in the damage of the fluid-saturated porous media. 相似文献
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为了深入研究液饱和多孔介质中应力波的传播,提出了三维两相细观计算模型.基于此模型。应用Galerkin余量法并计及流-固耦合界面的耦合效应,利用直接耦合的技术,开发了三维流-固混合显式动力有限元计算程序.在此基础上对冲击载荷作用下液饱和多孔介质中三维应力波的传播现象进行了数值模拟,并详细讨论了孔隙率,孔隙形状等因素对应力波传播主导波形的影响. 相似文献
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The present study deals with reflection and transmission of plane waves between two different fluid-saturated porous half-spaces,
where longitudinal and transversal waves impinge obliquely onto the interface. Amplitude ratios of various reflected and transmitted
waves are obtained. Variations of amplitude ratios with the angle of incidence are depicted graphically. A particular case
of reflection at the free surface of the fluid-saturated porous half-spaces is discussed. 相似文献
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A conceptual model is developed in this article that accounts for the effect of slow and fast moving liquid zones on solute
transport in porous media. The liquid phase within the porous media is divided into three zones—immobile, slow moving, and
fast moving. Slow moving liquids surround the solid particles in thin layers and have lower velocity in flow. Fast moving
liquids have higher velocity and are not in contact with the solid particles. Solute mass transfer occurs between the slow
and fast liquids, and the slow and immobile liquids. The immobile and slow moving liquids interact with the solid matrix in
the media through the mechanism of sorption and desorption. Implicit finite-difference methods are used to solve the partial
differential equations that describe the slow and fast movement of solute in the porous medium. The model was validated for
a laboratory column experimental data. Sensitivity analyses were conducted to ascertain the effects of the model parameters
on solute movement. The effect of each parameter on retardation of the solute movement was analyzed. It was observed that
the maximum retardation of solute occurs when there is high adsorption coefficient, high mass transfer rates, and high volume
of slow moving liquid in the porous media. 相似文献
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According to generalized characteristic theory, a characteristic analysis for stress wave propagation in transversely isotropic fluid-saturated porous media was performed. The characteristic differential equations and compatibility relations along bicharacteristics were deduced and the analytical expressions for wave surfaces were obtained. The characteristic and shapes of the velocity surfaces and wave surfaces in the transversely isotropic fluid-saturated porous media were discussed in detail. The results also show that the characteristic equations for stress waves in pure solids are particular cases of the characteristic equations for fluid-saturated porous media. 相似文献
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P. Phurkhao 《International Journal of Solids and Structures》2013,50(25-26):4292-4304
Diffraction of normal compression waves by a penny-shaped crack in a fluid-saturated porous medium is investigated. Two wave types are considered, namely, compressional wave of the first kind, and the second kind. The former, also known as fast wave, propagates primarily through the solid, whereas the latter or slow wave, propagates mainly in the fluid. Each wave propagates in the medium along with induced wave of the same type in the companion constituent of the material. Application of Biot’s theory in conjunction with integral transform technique reduces the problem to a mixed boundary-value problem whose solution is in turn governed by a Fredholm integral equation of the second kind. Near-field and far-field solutions are obtained in terms of the dynamic stress-intensity factor and the scattering cross section, respectively. They are of particular importance to the linear elastic fracture mechanics (LEFM) and in the scattering theory of elastic waves. The mode I stress-intensity factors are computed numerically for a set of selected material property values, and shown graphically for various mass density and viscosity-to-permeability ratios. The obtained results reveal significant impact of the presence of pore fluid upon the stress-intensity factors, both magnitudes and frequencies at their peak values. The influence of the fluid is also observed from the calculated scattering cross sections of the scattered far-field. Accuracy of the present solution procedure is verified by comparing the numerical results with existing results in the limiting case of dry elastic materials. 相似文献
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Eduard Rohan 《Theoretical and Computational Fluid Dynamics》2006,20(4):251-276
The homogenization approach to multiscale modeling of soft biological tissues is presented. The homogenized model describes the relationship between the macroscopic hereditary creep behavior and the microflow in a fluid-saturated dual-porous medium at the microscopic level. The micromodel is based on Biot’s system for quasistatic deformation processes, modified for the updated Lagrangian formulation to account for coupling the fluid diffusion through a porous solid undergoing large deformation. Its microstructure is constituted by fluid-filled inclusions embedded in the porous matrix. The tangential stiffness coefficients and the retardation stress for the macromodel are derived for a time-stepping algorithm. Numerical examples are discussed, showing the strong potential of the model for simulations of deformation-driven physiological processes at the microscopic scale. 相似文献
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The present study investigates novelties brought into the classic Biot's theory of propagation of elastic waves in a fluid-saturated porous solid by inclusion of non-Newtonian effects that are important, for example, for hydrocarbons. Based on our previous results (Tsiklauri and Beresnev, 2001), we investigated the propagation of rotational and dilatational elastic waves by calculating their phase velocities and attenuation coefficients as a function of frequency. We found that the replacement of an ordinary Newtonian fluid by a Maxwell fluid in the fluid-saturated porous solid results in: (a) an overall increase of the phase velocities of both the rotational and dilatational waves. With the increase of frequency these quantities tend to a fixed, higher level, as compared to the Newtonian limiting case, which does not change with the decrease of the Deborah number . (b) The overall decrease of the attenuation coefficients of both the rotational and dilatational waves. With the increase of frequency these quantities tend to a progressively lower level, as compared to the Newtonian limiting case, as decreases. (c) Appearance of oscillations in all physical quantities in the deeply non-Newtonian regime. 相似文献
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基于饱和多孔介质理论,在固相和液相微观不可压,固相骨架小变形且满足线性粘弹性积分型本构关系的假定下,建立了流体饱和粘弹性多孔介质动力响应的若干Gurtin型变分原理,包括Hu-Washizu变分原理.利用所建立的变分原理,导出了流体饱和粘弹性多孔介质动力响应无网格数值模拟的离散控制方程,此方程是一个关于时间的对称微分方程组,便于分析计算.作为数值例子,研究了流体饱和粘弹性多孔柱体的一维动力响应,数值结果揭示了流体饱和粘弹性多孔柱体中波的传播特性以及固相粘性的影响. 相似文献
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A study of body waves in fractured porous media saturated by two fluids is presented. We show the existence of four compressional and one rotational waves. The first and third compressional waves are analogous to the fast and slow compressional waves in Biot's theory. The second compressional wave arises because of fractures, whereas the fourth compressional wave is associated with the pressure difference between the fluid phases in the porous blocks. The effects of fractures on the phase velocity and attenuation coefficient of body waves are numerically investigated for a fractured sandstone saturated by air and water phases. All compressional waves except the first compressional wave are diffusive-type waves, i.e., highly attenuated and do not exist at low frequencies.Now at Izmir Institute of Technology, Faculty of Engineering, Gaziosmanpasa Bulvari, No.16, Cankaya, Izmir, Turkey. 相似文献
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Based on the finite deformation theory of the continuum and poroelastic theory, the aeoustoelastic theory for fluid-saturated porous media (FSPM) in natural and initial coordi- nates is developed to investigate the influence of effective stresses and fluid pore pressure on wave velocities. Firstly, the assumption of a small dynamic motion superimposed on a largely static pre- deformation of the FSPM yields natural, initial, and final configurations, whose displacements, strains, and stresses of the solid-skeleton and the fluid in an FSPM particle could be described in natural and initial coordinates, respectively. Secondly, the subtraction of initial-state equations of equilibrium from the final-state equations of motion and the introduction of non-linear constitu- rive relations of the FSPM lead to equations of motion for the small dynamic motion. Thirdly, the consideration of homogeneous pre-deformation and the plane harmonic form of the small dynamic motion gives an acoustoelastic equation, which provides analytical formulations for the relation of the fast longitudinal wave, the fast shear wave, the slow shear wave, and the slow longitudinal wave with solid-skeleton stresses and fluid pore-pressure. Lastly, an isotropic FSPM under the close-pore jacketed condition, open-pore jacketed condition, traditional unjacketed condition, and triaxial condition is taken as an example to discuss the velocities of the fast and slow shear waves propagating along the direction of one of the initial principal solid-skeleton strains. The detailed discussion shows that the wave velocities of the FSPM are usually influenced by the effective stresses and the fluid pore pressure. The fluid pore-pressure has little effect on the wave velocities of the FSPM only when the components of the applied initial principal solid-skeleton stresses or strains are equal, which is consistent with the previous experimental results. 相似文献
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The objective of this article is to derive a macroscopic Darcy’s law for a fluid-saturated moving porous medium whose matrix
is composed of two solid phases which are not in direct contact with each other (weakly coupled solid phases). An example of this composite medium is the case of a solid matrix, unfrozen water, and an ice matrix within the pore space.
The macroscopic equations for this type of saturated porous material are obtained using two-space homogenization techniques
from microscopic periodic structures. The pore size is assumed to be small compared to the macroscopic scale under consideration.
At the microscopic scale the two weakly coupled solids are described by the linear elastic equations, and the fluid by the linearized Navier–Stokes equations with appropriate
boundary conditions at the solid–fluid interfaces. The derived Darcy’s law contains three permeability tensors whose properties
are analyzed. Also, a formal relation with a previous macroscopic fluid flow equation obtained using a phenomenological approach
is given. Moreover, a constructive proof of the existence of the three permeability tensors allows for their explicit computation
employing finite elements or analogous numerical procedures. 相似文献
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川藏公路地质环境与整治改建方案的思考 总被引:3,自引:1,他引:3
川藏公路由于地质环境复杂、建设标准低、后遗病害多,抗灾能力差,泥石流、滑坡、山崩、雪害、水毁等自然灾害频繁发生,公路阻车断道严重。国家投入巨资进行整治改建,并取得了明显的效果,但由于自然环境特殊、影响因素复杂,许多特大型、大型工程地质病害问题还没有可行、可靠的解决方案。本文通过分析川藏公路沿线的地质环境和灾害特点,总结历年整治改建和经验的教训,提出川藏公路建设的途径、可能达到的目标和应采用的原则。 相似文献
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横观各向同性液体饱和多孔介质中平面波的传播 总被引:11,自引:2,他引:11
基于孔隙介质的Biot理论1,研究了横观各向同性液体饱和多孔介质中平面波的传播特性。首先导出了波传播的特征方程并给出了其解析解,结果显示:有4种不同波速的平面体波传播;第一准纵波,第二准纵波,准横波和反平面横波。文中给出了波速和衰减的解析表达式,数值计算了频散曲线和衰减曲线,并讨论了各类准体波位移之间的耦合关系。 相似文献
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This article deals with the theoretical aspects of chemical-dissolution front instability problems in two-dimensional fluid-saturated
porous media including solute dispersion effects. Since the solute equilibrium concentration is much smaller than the molar
density of the dissolvable mineral in a mineral dissolution system, a limit case, in which the ratio of the solute equilibrium
concentration (in the pore fluid) to the molar density of the dissolvable mineral (in the solid matrix of the porous medium)
approaches zero, is considered in the theoretical analysis. Under this assumption, the critical condition under which a planar
chemical-dissolution front becomes unstable has been mathematically derived when solute dispersion effects are considered.
The present theoretical results clearly demonstrated that: (1) the propagation speed of a planar chemical-dissolution front
in the case of considering solute dispersion effects is the same as that when solute dispersion effects are neglected. This
indicates that solute dispersion does not affect the propagation speed of the planar chemical-dissolution front in a fluid-saturated
porous medium. (2) The consideration of solute dispersion can cause a significant increase in the critical Zhao number, which
is used to judge whether or not a planar chemical-dissolution front may become unstable in the fluid-saturated porous medium.
This means that the consideration of solute dispersion can stabilize a planar chemical-dissolution front, because an increase
in the critical Zhao number reduces the likelihood of the planar chemical-dissolution front instability in a fluid-saturated
porous medium. In addition, the present results can be used as benchmark solutions for verifying numerical methods employed
to simulate detailed morphological evolution processes of chemical dissolution fronts in two-dimensional fluid-saturated porous
media. 相似文献
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The features of propagation of one-dimensional monochromatic waves and dynamics of weak perturbations with axial and central symmetries in liquid-saturated porous medium are investigated. Non-stationary interaction forces and viscoelastic skeleton characteristics are taken into account. The research is carried out within the two-velocity, two-stress tensor model by applying methods of multiphase media mechanics. The system of equations is solved numerically by applying Fast Fourier Transform (FFT) algorithm. The influence of geometry of the process on wave propagation behavior is studied.It is shown that the initial pressure perturbation splits into two waves: fast (deformational) wave and slow (filtrational) one. Each of them is followed by the balance wave: that is, rarefaction wave after compression wave and compression wave after rarefaction wave; at that slow wave and balance one following fast wave may interfere. 相似文献
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GURTIN VARIATIONAL PRINCIPLE AND FINITE ELEMENT SIMULATION FOR DYNAMICAL PROBLEMS OF FLUID-SATURATED POROUS MEDIA 总被引:8,自引:0,他引:8
Yang Xiao Cheng Changjun Department o f Mechanics Shanghai Institute of Applied Mathematics Mechanics Shanghai University Shanghai China) 《Acta Mechanica Solida Sinica》2003,16(1):24-32
Based on the theory of porous media,a general Gurtin variational principle for theinitial boundary value problem of dynamical response of fluid-saturated elastic porous media isdeveloped by assuming infinitesimal deformation and incompressible constituents of the solid andfluid phase.The finite element formulation based on this variational principle is also derived.Asthe functional of the variational principle is a spatial integral of the convolution formulation,thegeneral finite element discretization in space results in symmetrical differential-integral equationsin the time domain.In some situations,the differential-integral equations can be reduced to sym-metrical differential equations and,as a numerical example,it is employed to analyze the reflectionof one-dimensional longitudinal wave in a fluid-saturated porous solid.The numerical results canprovide further understanding of the wave propagation in porous media. 相似文献