Verification of Initial Mining Height Recovery Technology and Top Coal Caving Promotion Effect in Coal Seam Fully Mechanized Caving
During the initial mining of the coal mining working face in Hulonggou Coal Industry,there are problems such as large block size,low recovery rate of top coal caving and so on,resulting in serious waste of coal resources.According to the actual situation of the mine,a recovery scheme based on hydraulic fracturing technology is designed.Through numerical simulation analysis of the coal rock fracture law and top coal transportation situation after the caving promotion,a hydraulic fracturing drilling scheme is formulated for the initial mining stage.The results show that after constructing hydraulic fracturing drilling,hydraulic fractures are formed at the coal rock interface,which together with the existing natural fractures form a fracture grid,improving the overall caving performance;The top coal and basic top cracks are well developed,and some of the top coal develops into a network crack structure;The basic top crack length accounts for 25%of the total crack length;Compared with adjacent unfractured working faces,the average recovery rate of top coal in the initial mining stage after fracturing and caving promotion increases by 42%,shortens the initial pressure step distance by about 30 m,and the periodic pressure step distance by about 20 m,which to some extent reduces the resistance of support work and reduces the probability of coal wall caving and roof leakage between frames.
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