Study On Mechanism Of Fault-induced Activation Water Inrush Induced By Working Face Mining And Application Of Grouting Reinforcement

During the coal seam mining process,the presence of confined water in the fault and floor greatly increases the risk of water inrush when mining near the working face.In actual engineering,in order to avoid the occurrence of water inrush accidents,a faulty waterproof coal pillar with a large width is usually left,but at the same time,a large amount of coal resources are wasted.Based on the actual geological conditions of the F4 fault in Wugou Coal Mine,this paper uses theoretical analysis,laboratory tests,numerical simulations and engineering practices to consider the characteristics of the fault activation and the fault-waterproof coal pillars after grouting.The problem was studied.The main conclusions are as follows:(1)Through theoretical analysis,the stress transfer mechanics model is constructed for the mining stress variation of the upper and lower face of the fault.It is concluded that the fault has a more obvious effect on the stress transfer barrier when the lower face is mined.The mechanical model is constructed for the fault activation mechanism and the fault activation mechanics is given.(2)Through laboratory tests,for the physical properties of the slurry in the grouting project,cement,bentonite,water reducing agent and water glass are used as raw materials,and the water-splitting rate,viscosity and setting time of the slurry are measured by single factor test and orthogonal test method.The physical properties such as stone strength were optimized,and the ratio of the slurry with better performance was obtained.(3)Through the similar material test,the system analyzes the stress transfer law during the mining of the upper and lower working faces of the fault,and draws the difference;The evolution law of the floor stress during the mining of the upper face of the fault is analyzed.It is concluded that the closer the floor is to the fault during the mining process,the greater the peak value of the stress and the more serious the damage;The variation law of the stress in the interrupted layer of the mining face is analyzed,and the closer the working face is to the fault,the more obvious the fault is affected by the mining.The analysis of the residual coal pillars before and after grouting is carried out,and the grouting reinforcement of the fault is obtained.Afterwards,the width of the fault waterproof coal pillar can be effectively reduced.(4)The numerical simulation is used to study the stress variation law,plastic failure characteristics and seepage characteristics of the fault zone under different working conditions such as aquifer water pressure and fault grouting.The fault peak stress and fault waterproof coal are obtained.The column width is negatively correlated and positively correlated with the water pressure value;The plastic failure range is negatively correlated with the width of the fault waterproof coal pillar and positively correlated with the water pressure;the water flow vector is negatively correlated with the width of the fault waterproof coal pillar and positively correlated with the water pressure value;compared with the grouting before grouting The normal stress of the posterior fault zone increases,the shear stress decreases,the plastic damage range becomes smaller,and the water flow vector decreases.(5)Through engineering practice,grouting and strengthening F4 fault and further reducing the width of fault waterproof coal pillar,verifying the feasibility of theoretical research,providing a scientific basis for mine safety production and improving coal resource recovery rate.