Study On Pressure Relief And Scour Prevention Control Of Mining Roadway In Fully Mechanized Caving Face With Hard Roof

The stability of mining roadway in fully mechanized caving face with hard roof is an important guarantee for safe and efficient mining face.The hard roof has the characteristics of high strength,large thickness and difficulburstt caving.Mining can easily lead to stress concentration and induce roadway rock.It is of great significance to study and determine the parameters of pressure relief and scour prevention for large diameter boreholes in roadways to avoid rock burst disaster of coal pillars and realize safe mining.Aiming at the roadway safety control of W1123 fully mechanized caving face in B2 coal seam of Kuangou Coal Mine,in this study,the control of pressure relief and scour prevention in the mining roadway of fully mechanized caving face with hard roof problems was analyzed by means of field investigation,theoretical analysis,numerical simulation and field industrial test.The main research achievements include the following aspects:The geological occurrence conditions of B2 coal seam are studied by investigating the on-site mining technique conditions.The relationship between deformation and failure of roadway and mining of working face is analyzed by monitoring the deformation and internal stress of transportation roadway in W1123 fully mechanized top coal caving face.The theoretical analysis method is adopted to analyze the principle of pressure relief and energy absorption of large diameter boreholes.The method of scour prevention and pressure relief of large diameter boreholes in coal pillars is proposed.The numerical calculation model of pressure relief of large diameter boreholes and the orthogonal experiment of borehole parameters are established to simulate the pressure relief effect of large diameter boreholes and the parameter factors influencing the pressure relief effect of large diameter boreholes.Completed the three-dimensional FLAC3D modeling and numerical calculation,the results show that large diameter borehole pressure relief is arranged in high stress coal,which changes the high stress state of roadway coal,forms a pressure relief zone in high stress area,and forms a large plastic deformation zone around the borehole.Therefore,the effect of weakening the coal body and absorbing the elastic deformation energy is achieved.The diameter of borehole is 300mm,the depth is 12m and the spacing is 2.0m.The engineering practice results show that the stability of roadway is obviously improved after large diameter borehole pressure relief and reinforcement support and the deformation of surrounding rock is controlled,which plays a role in preventing the occurrence of rock burst and guarantees the safe and efficient mining face.This study has a good scientific basis and practical value for the stability failure of coal and rock mass in the roadway of hard roof fully mechanized top coal caving face and the selection of risk relief methods,which provides a reference basis for the selection of scour prevention and risk relief methods in mines with similar geological conditions.