Research On Variable Mass Fluid-solid Coupling Dynamic Theory Of Broken Rockmass And Application

As the mining activity rapidly develop to deep ground for day by day, coal minewater inrush accidents become one of the most serious disaster that threaten the saftymining in China. The water inrush accidents number rank thrid behind coal mine gasexplosion accidents and roof accidents, while ranking top in terms of economicloss.Seepage characteristic and mutation rule of broken rock mass is the basis of coalmine water inrush mechanism. In this paper, we systemtically investigated the variablemass fluid-solid coupling theory and Karst collapse column water inrush mechanism byusing methods involving theretical analysis, numerical simuation and experiments, andobtained the following results:(1) We independently designed an equipment and the experiment system which cantake particle transport into account, and successfully tested the seepage mutation ruleunder the conditions of different proportion, axial pressure and so on, obtaining thefilling material flow velocity, porosity, water pressure and flow volume as the time forbroken rock mass.(2) Based on the continuous medium mechanics, we built a variable massfluid-solid coupling model including solid deformation, particle transport and fluidseepage, deducing the mass conservation and moment conservation for the broken rockmass seepage, obtaining the governing equations of porosity evolution under conditionsof erosion and particle transport, and getting the porosity, permeability, filling materialflow ration, water inflow volume and water pressure for broken rock mass.(3) We carried out the X ray diffraction testing for filling material of Karst collapsecolumn and obtained the components and content of the filling material; We tested theparticle size distribution characteristics of the filling material by using hydrometeranalysis, and obtained the particles size distribution curves, and detail analysis the effectof component and particle size distribution on the seepage characteristics of Karstcollapse column.(4) We analyzed and evaluate the Karst collapse column water inrush risk by usingnumerical simulation method, obtaining the water inflow volume, Karst collapse columeand particle transport ratio change under different conditions including aquifer pressure,surrounding rock strength, initial porosity of Karst collapse column and working faceadvanced distance, which can provide reference for the coal pillar leaving.The research results can provide important reference for coal mine water inrushmechanism, prediction method and prevention technics.