Research On The Effect Of Grouting Plugging And Seepage Reduction In Fractured Coal Body And The Application Of Drainage Drilling And Sealing

Drilling gas drainage is the main method for coal seam gas prevention and utilization in my country.However,due to the double pressure relief effect of roadway and drilling hole,there are a large number of crack channels around the drilling hole,which seriously affects the drainage effect.The key factor that affects the effect of gas drainage is the sealing quality.However,the sealing quality of the drainage holes in most coal mines in my country cannot meet the requirements.Therefore,it is an urgent engineering problem to reveal the effect of grouting plugging and seepage reduction in drainage drilling holes and improve the sealing performance of drilling holes,which is beneficial to improve the safety of coal mines.In order to study the effect of grouting plugging and seepage reduction in fractured coal body and the application of drainage drilling and sealing,this paper comprehensively uses laboratory experiments,theoretical analysis,numerical simulation and field engineering experiments on the basis of the research on the distribution of fractures.Taking the actual engineering geological conditions of a coal mine in Anhui as the background,FLAC^3D and COMSOL software are used to establish a gas drainage hole grouting and sealing model and carry out relevant numerical simulation experiments to reveal the effect of drainage hole grouting to plug leakage and reduce seepage.Field engineering experiments were optimized and reasonable sealing parameters were obtained,which provided a solid foundation for reasonable sealing and efficient gas drainage of underground gas drainage holes in coal mines.The main research results are as follows:（1）Carry out grouting experiments and permeability measurement experiments under different confining pressures,grouting pressures,and water-cement ratios of the fractured coal body.The measurement results show that the permeability of the coal body before and after grouting has decreased significantly,and the decline rate is 90%.The above shows that the effect of grouting to plug leakage and reduce seepage is obvious.With the increase of the confining pressure,the permeability of the fractured coal body before and after grouting keeps decreasing;with the increase of grouting pressure,the decrease of the permeability of the coal body after grouting also keeps increasing With the decrease of water-cement ratio,the better the grouting effect of coal body,the greater the decrease of permeability.（2）The grouting plugging model of the loaded fractured coal body is established through theoretical analysis,and the numerical calculation model of grouting of the fractured coal sample is established on this basis.The change of permeability,the final simulation results and the experimental results have a high consistency,which proves the correctness of the theory and the reliability of the fractured coal body plugging model.（3）Based on the actual engineering geological conditions of Anhui coal mine,FLAC^3D software is used to simulate and analyze the distribution characteristics of coal stress and plastic zone under the double pressure relief of roadway and borehole in the actual situation.With the continuous deepening from the roadway wall,the distribution range of the plastic zone of the coal body around the borehole continues to shrink.When the borehole is in the pressure relief zone formed after the roadway excavation,the radius of the plastic zone is the largest;when the borehole is under stress When the borehole is in the concentration zone,the radius of the plastic zone gradually decreases with the depth;when the borehole is in the original rock stress zone,the plastic zone is the smallest.（4）With the help of COMSOL numerical simulation software,the numerical calculation model of grouting and sealing of gas drainage holes under field conditions was established,and the leakage law of gas drainage holes and the effect of grouting and sealing under different grouting parameters were simulated and studied.And conduct on-site engineering experimental research in 360803 working face of Anhui Coal Mine,and select reasonable sealing parameters.The research results show that the grouting pressure and the water-cement ratio of the slurry have an important influence on the grouting hole sealing effect.Combined with the feasibility and simulation effect of the actual operation on site,the optimal grouting pressure is 1.2MPa;And the fluidity of the slurry,the optimal water-cement ratio of the slurry is 1.0.The paper has 48 figures,9 tables,and 73 references.