Mathematical Model Study On Liquid-Solid Coupling Of Water-Air Two-Phase Flow Infiltrating And Double Porosity Deforming

Based on rock hydraulics and multiphase seepage mechanics, the engineering geologic body is simplified as double porosity media, and the coupled effects of water-air two-phase flow penetrating and double porosity media deforming are studied systematically. The main researches include water-air two-phase flow penetrating theories, mechanical behavior of complicated porous media with pore-fissure structure and the analysis of coupled effects. The followings are some of the major works in detail in this dissertation:(1) To the duality of pore-fissure structure in rock and soil, one kind of new constitutive relation, classical elastic-plastic-damage combination model, is developed for double porosity media. In this model, the mechanical behavior of the part which contains pores is described with the classical elastic-plastic constitutive model; while to the part which contains fissures, the damage model is referred. And to the double porosity media, as a combination of pores and fissures, the elastic-plastic-damage combination model is presented to model its constitutive relation. In addition, a method of weight coefficients distribution is provided, which is able to illustrate the allocated effects or functions of pores and fissures.(2) From the viewpoint of system science, the interconnecting and interactional geologic solid body and liquids within are considered one system, and the coupled effects mechanics of water-air two-phase flow infiltrating and double porosity media deforming are analyzed. Furthermore, continuum mechanics is applied to derive the theoretical formulations of two-phase flow seeping and pore-fissure dual rock medium deforming. The mathematical formulations, combined with the boundary and initial condition equations, form the mathematical model, which reflects the coupling process of two-phase flow seeping and rock deforming.(3) The resultant governing equations of the mathematical model are very complex in both expression and mathematical properties. In order to derive an efficient numerical solution scheme, an uncoupled equation system is proposed. With the system, the uncoupled equations describing water-air two-phase flow pressure, saturation, and rock or soil deformation are established. Moreover, the numerical solution formulas with Galerkin finite element method are provided.(4) Lack of data, inaccurate parameters given and scale effect problems are bottleneck difficulties in research of geologic rock. In order to avoid these problems, the artificial neural network (ANN) nonlinear method for parameter recognition is adopted to inverse the mechanical and hydraulic parameters, and a method. Interval Rating method, determining approximately the nodes number of neural network is developed. Moreover, an example is analyzed to illustrate and verify the ANN method.(5) With the computer program design method of modularization, computer languages VC++, VB and Visual Fortran mixed programming technique and object-oriented finite element method (FEM) are adopted to develop a FEM-based computer program, which is utilized to compute and simulate the liquid-solid coupling phenomena of water-air two-phase flow and pore-fissure double porosity rock and soil medium.(6) Theoretical analysis and numerical analysis, qualitative analysis and quantitative analysis, and static simulation and dynamic simulation are combined to illustrate the example. To the specific problem, different methods are adopted, which makes the study of more scientificalness and practicality.