Research On The Key Technology Of Regional Outburst Prevention Of Steeply Lower Protective Layer With Gob-side Entry Retaining

In order to solve the serious gas outburst hazard of three soft coal seam which difficult to drainage, this paper puts forward the protective layer regional comprehensive outburst prevention technology, In Li Gou mine of Yima Coal Group one 8 and two 1 coal seam are taken as the research object. after the protective seam mining, research the situation of pressure relief and expansion deformation of protected layer in the influence of mining, and extract the gas of pressure releasing area.By analyzing the controlling factors of coal seams outburst, investigating two 1 coal and one 8 coal, and predicting gas emission of working face. protection layer is put forward to control the gas of work face, followed by feasibility study for protective layer mining. take the technical gob-side entry retaining as arrangement of borehole to drainage the protected layer gas in 12050 working face roadways; expansion rate of two 1 coal seam is measured with deep base point method, the change of permeability coefficient is investigated by arranging borehole after mining, expansion deformation rate and permeability coefficient are taken as the evaluation of the protective effect of index. determine the residual gas content of effect of comprehensive outburst prevention. The COMSOL multi field coupling method determine the drainage radius of borehole layout for optimization. The results show that the protected layer expansion deformation rate was 10.3‰, the permeability coefficient increased by 198 times, that prove pressure of 12052 is full relieved and has good protection effect, COMSOL determines the relieved drainage radius 6.5m, residual gas content measurement point is 2.33m3/t on average, 70% lower than the original gas content, the inverse residual gas pressure is much smaller than 0.74 MPa, this showed that the comprehensive outburst prevention of protective layer and achieved very good results, eliminates the protected layer working face outburst. comprehensive outburst prevention technique of lower protective layer provides guidance and basis to control gas in three soft.