Study On Seepage Law Of Isolated Overburden Grout Injection Slurry Bleeding Water

Isolated overburden grout injection technology is an economical and efficient green mining technology,which scientifically solves the problems of surface subsidence control,aquifer protection,waste material utilization and mine earthquake treatment.In this technology,water is used as the medium to transport the solid medium into the separation space,and the injection slurry forms a compacted filling body in the separation space to compress the overlying expansion rock mass and support the overlying rock layer,so as to control the surface subsidence.In the grout injection process,there will be a large amount of slurry bleeding water leaking into the formation.The grout injection layer is generally located above the water-conducting fissure zone above the coal seam.Under certain conditions,the bleeding water of slurry will leak into the working face along the overlying strata,resulting in an increase in the water yield of the working face.Therefore,in order to ensure the safety of working face production and the effectiveness of grout injection,it is necessary to study the distribution characteristics of grout water in the stratum and the seepage law in the overlying strata,determine the conditions and influencing factors of bleeding water leaking into the working face,and establish the prediction method of bleeding water leaking into the working face.Obviously,the study of the above problems has important theoretical and practical value.To this end,this thesis focuses on the problem of slurry bleeding water seepage in isolated overburden grout injection technology,and comprehensively adopts the method of laboratory experiment,theoretical analysis,numerical simulation and engineering measurement,and obtains the following innovative research results:（1）The seepage distribution characteristics of slurry bleeding water in the lower rock layer of grouting horizon were revealed.A 3D visualization simulation experiment system of"diffusion-bleeding and seepage"of isolated overburden grout injection technology was developed by ourselves,and fluid-solid coupling similar materials for seepage of slurry bleeding water were given.Based on the experimental system,the slurry compression instrument and theoretical analysis,the characteristics of slurry diffusion,final and dynamic bleeding were revealed,and the formula of slurry bleeding water was derived.The distribution characteristics of slurry bleeding water seepage in strata and the four-stage variation characteristics of overlying rock saturation in slurry bleeding water seepage were revealed.The three-dimensional seepage form distribution characteristics of the"semi-ellipsoid"body are revealed,and the central point of the form moves towards the mining direction with the expansion of the mining fracture,and the theoretical equation of the seepage boundary is given.（2）The influence law of initial overburden saturation,grouting flow,overburden permeability coefficient and strike mining length on the seepage of slurry bleeding water was revealed.Based on the experimental results,the relationship formula between overlying initial saturation,grouting flow,permeability coefficient,strike mining length and seepage boundary of slurry bleeding water was established.The larger the initial saturation of overburden,the larger the grouting flow,the larger the permeability coefficient,the larger the strike mining length,the larger the seepage range,and the closer the vertical seepage boundary to the working face.When the effluent does not percolate to the aquifer,the seepage distribution pattern of the slurry bleeding water is not affected by the aquifer.When the slurry bleeding watert to the aquifer,the vertical seepage boundary does not change,and the horizontal seepage range gradually expands.（3）A method for predicting the leakage of slurry bleeding water seepage working face was established.The dimensionless formula of seepage boundary parameters was obtained according to the study of influencing factors of slurry bleeding water seepage.The concepts of seepage critical boundary and critical water capacity of slurry bleeding water seepage in overlying rock were put forward,the formula of critical water capacity was derived,and the method of discriminating slurry bleeding water leaking into working face and predicting the water yield were established.When the seepage boundary of slurry bleeding water was larger than the critical seepage boundary,the stope working face would produce slurry bleeding water.The formula of water yieldδ,q were established.The reliability of the method was verified by predicting the leakage of grout injection working face in Linhuan coal mine and Yuandian No.2coal mine.On this basis,the isolation of grouting filling grouting strata are given a choice of the critical height,the grouting seepage boundary strata and coal seam roof distance>|c₁|+Height of fracture zone of water conduction H_d.This dissertation contains 111 figures,30 tables and 167 references.