Study On Strata Pressure Law Of Fully Mechanized Mining Face With Large Mining Height In Shallow Coal Seam

The Wangjiata coal mine located in Shenfu mining area of Dongsheng coalfield in Wanli mining area southwest of the shallow buried coal seam, a small angle of overlying thick loose layer and the coal seam occurrence characteristics. Long term practice of shallow coal seam longwall mining shows that the pressure of shallow buried coal seam is more obvious than that of the common buried depth. According to the mining experience of 3101 - 3106 working face in the coal mine,the mine face pressure is relatively stable, there is no gas outburst, rock burst and other geological disasters, and the coal pillar of 20m mining roadway is safe. Combined with the actual geological conditions and mining conditions, the paper studied the movement law of the 3107 roof,the strata pressure and the reasonable coal pillar.First, using the key strata theory of key strata layer 3107 working surface are determined by theoretical calculations show that the roof, C1,C2 two key layer, using the transfer of rock beam theory and the key layer further analysis the damage of roof movement form instability mechanism. The results are then analyzed according to the KJ216 detection system on the working face of mine pressure law measured: the minimum setting force must be greater than 5760KN, pressure to step away from the 8.7 ? 42.0m,the cycle pressure and pressure to step away from the size and the alternation of working face pressure is relatively stable, further evidence of the overlying strata in two key layer then, on the three of the roadway surrounding rock dynamic monitoring that the roof and floor of the roadway and help the two largest moving amount was 34mm and 15.2mm respectively, the roadway pressure is small and weak deformation, indicating the existing tunnel and working face support method is reasonable and safe. Finally, theoretical analysis of rational width of coal pillar, the three surrounding rock displacement and the strata are analyzed using numerical simulation method, 20m wide coal pillar size allowed is reduced, in order to reduce the cost of increasing the recovery rate, 10-20m simulation of different width of coal pillar, analysis of the plastic deformation and displacement and stress nephogram, summarize mine reasonable width of coal pillars for 12-14m.