Stress Wave Propagation In Fluid-Saturated Porous Media Under Impact Loading

Geological material, no matter soil or rocks, has the characteristic, such as crystal grain structures, pores or micro-cracks etc., on micro-scale and usually contains fluid or gas in pores and micro-cracks. So the problems about geological material are really the problem of the interaction between the fluid, solid and gas. In practical engineering, reasonable solution of some important and key problems in common, such as the stability of the side slope in the explosion of water conservation construction; using explosion to improve the productivity in oil production etc., require the thoroughly research on the dynamic mechanics of fluid-saturated porous media under impacting loading from the theories, numerical simulations and experiments. The rational solution of these problems will have great effects on the scientific advances, financial improvement and development of the society in these engineering fields.The present thesis reviews the development process of the theory of porous media and summarizes systematically the state and major progress of the wave propagation problem in the fluid-saturated porous media. It consists of two parts: the first part (Chapter 2,3,4,5) studies the characteristic of elastic waves and surface waves in orthotropic fluid-saturated porous media using Biot's theory which is based on the substitutive model. In the second one (Chapter 6) , a new three-dimensional meso-calculating model, which is more coincided with the inner action mechanism of porous media, is proposed. Based on this model, the elastic wave propagation in fluid-saturated porous media under longitudinal impacting is discussed.In Chapter 2, based on generalized characteristics theory, characteristic analysis is carried out on the problem of stress wave propagation in orthotropic fluid-saturated porous media under longitudinal impacting. Differential equations for characteristic curves, velocity curves and slowness curves are given and the analytical expressions for wave fronts in orthotropic porous media are also obtained. The wave fronts in anisotropic fluid-saturated porous media are discussed in detail.In Chapter 3, the plane wave propagation in orthotropic fluid-saturated porous media is researched according to Biot's theory and the concept of dynamic permeability. Attenuation characteristic of fast wave, slow wave, quasi-transverse wave and anti-plane transverse wave are discussed and the combined effects of the anisotropy of the solid skeleton and fluid viscosity on the propagation characteristic of plane waves are analyzed numerically. The influence of horizontal anisotropy and fluid viscosity on the propagation characteristic of elastic waves is clarified.In Chapter 4, using Biot's theory, the characteristic of Rayleigh waves in transverselyin________________________________________Abstract________________________________________isotropic fluid-saturated porous media is researched. Considering fluid viscosity and compressibility of solid grains, the three-dimensional complex characteristic equations for Rayleigh waves are derived and the propagation speed and particle traces are calculated. The analysis about the effects of the fluid viscosity and material parameters on the Rayleigh waves are performed. The results show that the existing of the fluid phase has great influence on the propagation of Rayleigh waves. When compressibility of the solid grains are considered, the speed of Rayleigh waves is not only decided by the speed of the fast wave and the quasi-transverse wave in the solid skeleton, but also affected by the speed of the slow wave.In Chapter 5, based on Biot's theory for anisotropic fluid-saturated porous media, the Rayleigh waves in orthotropic non-viscous fluid-saturated porous media are studied. The numerical simulations show that the phase plane and amplitude plane in orthotropic fluid-saturated porous media is not paralleled to each other any more though the dispersion caused by the fluid is omitted. It is one kind of non-homogeneous wave. The maximum attenuation i...