Permeability Evolution And Groundwater Migration Characteristics Of Floor With Large Dip Angle And High Pressure

Based on the permeability characteristics of the mining floor and the groundwater movement characteristics under the conditions of large dip angle and high pressure,the hydraulic characteristics of the floor water resisting strata under the coupling of pressure and shear are analyzed,the equivalent permeability of the mining floor and the sensitivity of influencing factors are analyzed,the groundwater flow field and solute movement characteristics are determined,the floor equivalent water blocking thickness and the feasibility evaluation method of floor water in-situ protection are proposed,and the field industrial test is carried out,The following research results have been achieved:(1)The pore structure characteristics of water resisting rock in the floor are analyzed,the hydraulic characteristics of rock under the coupling of pressure and shear are determined,and the permeability characteristics of water resisting rock under different dip angles and water pressures are revealed.Based on T2 NMR spectrum,the correlation between rock micro pore structure and multifractal characteristics is clarified,and the influence of osmotic pressure difference on rock fracture stress threshold and permeability is determined.The instability criterion of rock considering the deflection effect of principal stress and the mechanical mechanism of crack propagation are established,and the influence mechanism of confining pressure effect and seepage stress under different dip angles and water pressures on the permeability characteristics of water resisting strata is revealed.The coupling equation of seepage damage stress considering plastic strain and dilatancy effect is established,and the transformation process of bond weakening and friction strengthening during rock fracture is verified.(2)The distribution of floor stress environment and the main control factors of failure are revealed,and the characteristics of structural instability and seepage instability of water resisting strata are clarified.Based on the measured data of floor failure depth,a prediction model of floor failure depth considering the boundary between deep and shallow is proposed and verified.Based on the semi infinite plane stress transfer,the stress environment and failure characteristics of the floor under different dip angles and water pressures are determined.A mechanical model of the stability of the non uniformly distributed aquiclude considering water pressure and overburden stress is established,and the primary and secondary order of the influence of various factors on the stability of the aquiclude is determined.The seepage instability criterion of Forchheimer type non Darcy seepage system considering seepage refraction effect is constructed.(3)The characteristics of equivalent permeability and energy release of the floor under the condition of large dip angle and high pressure are revealed,and the floor water inflow mode and main control factors are obtained.A numerical characterization method of mining permeability and acoustic emission to distinguish loading and unloading times and elastic-plastic state is proposed and verified.The feasibility of equivalent permeability theory is determined by the correlation between equivalent permeability and seepage path.The characteristics of floor failure depth and equivalent permeability evolution under different water pressure and dip angle conditions are analyzed,and the location of energy release concentration in the surrounding rock of the stope floor and the main controlling factors of the floor equivalent permeability are determined.The dominant seepage path driven by the combination of upper ends of the working face and high seepage stress under the condition of large dip angle is revealed.(4)The characteristics of groundwater drawdown and solute transport under different equivalent permeability are determined,and the feasibility evaluation method of in-situ protection of floor confined water is proposed.A generalized general coupling model of groundwater including flow regime transformation,mass loss and damage effect is established,and the characteristics of groundwater drawdown and solute distribution under different equivalent permeability conditions are analyzed.The equivalent permeability model of mining floor with cooperative deformation of floor is constructed,the influence mechanism of different factors and lithological combination on equivalent permeability is analyzed,and the competitive mechanism of permeability caused by changes of strain and deflection of neutral layer with dip angle is revealed.Based on the conservation of flow and the three equivalent theory,the calculation method of equivalent water blocking thickness and equivalent permeability of mining floor,the evaluation of water resources carrying capacity with the threshold of water level drawdown and the judgment steps of floor water in-situ protection are proposed.(5)A multi parameter coupling model of equivalent permeability based on response surface method is established,the water inrush coefficient of mining floor is evaluated,and the chemical characteristics of mine water and the determination and identification of floor water source are determined.A quadratic equivalent permeability multi parameter coupling model suitable for the actual formation conditions of Fenyuan Mine is established,and the response degree of single factor and interaction effect to equivalent permeability is analyzed.Based on improved entropy and analytic hierarchy process,the safety mining of floor in mining area is evaluated.The hydrochemical characteristics and water rock interaction modes of different types of groundwater are clarified,and a multi-dimensional water source determination method is proposed.The in-situ protection of floor water is identified from the perspective of water volume and water source,and is successfully applied to the field practice.This thesis has 157 figures,34 tables and 293 references...