Numerical Simulation Study On Characteristics Of Top Coal Release From Fully Mechanized Mining In Extra Thick Coal Seam

In order to study the law of the top coal release in the thick coal seam,the practical conditions of the fully mechanized top coal caving face in Datong mining area are the engineering basis,and the three-dimensional geological modeling,theoretical analysis and numerical simulation are used as the research means.Combined with CAD,SUFFER and ANSYS software for coal seam three-dimensional geological modeling.Through the theory of key layer,the characteristics of overlying strata in working face are analyzed.The numerical simulation method was used to study the release law of top coal,and the coal process was optimized.The theoretical formula of the main coal caving parameters which affect the normal production of working face is deduced by theoretical analysis.Research indicates: Through the three-dimensional modeling of coal seam,the occurrence status of coal seam with different spatial position can be obtained intuitively.With the increase of the thickness of the top coal,the effective release rate of the top coal is gradually reduced.For the traditional coal-free process,the top coal release time of single bracket hydraulic is irregular,however,automated coal release is regular and easy to operate.The ejector of the top coal is approximately elliptical in the direction of the working face and is irregularly elliptical in the direction of the working face.Increase the coal step,the top coal release rate decreased.Multi-round automated coal caving process can make coal gangue sub-interface gently subsidence,effectively improve the top coal release rate,reduce the rate of gangue.Through theoretical analysis,the relationship between the single-shot time and the overall working time is established,the relationship between the number of brackets in the coal release state and the coal handling power of the rear scraper is established.