Mechanism Study And Finite Element Simulation Of Multi-phase Coupling Piping

China has large population and inadequate water, water resource distribution is uneven temporally and spatially, flood disaster occurs frequently and many other factors led to the construction of a large number of Water Resources and Hydropower projects. Water Resources and Hydropower projects across the country makes the safety and stability critical. Piping is an important induced factor, but because of the complexity and randomness of piping, there are still many disputes on the study of its mechanism, there is no generally accepted theory with the most appropriate method, so study the development process and steady state has important theoretical and practical value. Based on the achievement in the past, series research of experiments, theoretical analysis and computing simulations on occurrence and development process and steady state of piping are presented, governing equations of piping are given, finite element simulation are applied, the main contents of this paper include the following aspects:(1) Based on a large number of collection and studied of literature at home and abroad, including the theoretical research, experimental study and numerical simulation, summarize the research status of piping.(2) According to the characteristics of piping and the former study, assumes that the soil is made up of three phase:the fluid, the skeleton solids, the fluidized-solids, based on the theory of fluid dynamics in porous media establish the differential equations of three phases, introduce the traditional constitutive equations of seepage erosion, governing equations of piping are established combine with the Darcy’s law. The occurrence and development process and steady state of piping are summarized according to the laboratory experiment of piping, concept the initial hydraulic gradient and stable porosity, the relations of stable porosity and hydraulic gradient are established, modify the traditional constitutive equation of seepage erosion.(3) Discrete spatial domain of the piping governing equations by the Galerkin finite element method, discrete time domain of the piping governing equations by the finite difference method, simulating the production of solids in wells and other axisymmetric piping with the program of finite element.(4) The embankment dam piping is the process of seepage erosion with free surface, numerical simulating the embankment dam piping process by combining the Bathe Method and the governing equations of piping under the condition of two-dimensional, this numerical simulation can show the development process and the steady state of embankment dam piping.