Study On The Movement And Gas Emission Law Of The Compound Roof Of Coal Seam And Oil Shale

In response to the abnormal gas emission in the upper corner of the fully mechanized coal face with compound roof of coal mass and oil shale rock in the coal bearing strata of Triassic system,take the example of the mining geological conditions of the 50212 and 50109 fully mechanized coal faces in Guantun coal mine,based on the methods of field investigation,theoretical analysis,laboratory experiment,physical similarity simulation experiment,numerical simulation and field experiment,to analyze the movement and gas emission of the compound roof are studied.The main conclusions are as follows:(1)When mining 5#coal seam in the Fully mechanized coal face of Guantun coal mine,mining about 20m,the immediate roof collapses for the first time.As the coal face continues to mine,the 6#coal seam and oil shale compound roof will collapse with the mining.When the coal face mines about 50m,the basic roof will break for the first time and the periodic weighting distance is about 18m.(2)When mining 5#coal seam in the Fully mechanized coal face of Guantun coal mine,The range of the sum of the caving and fracture zone is about 21m,and the 6#coal seam and oil shale are located in the caving and fracture zone.(3)The gas content of 5#,6#coal seams and oil shale in Guantun coal mine is 2.71m3/t,2.40m3/t and 0.09m3/t,respectively.The gas emission of Guantun coal mine is predicted by the method of separate source prediction.the coal face and goaf,heading face accounts for about 68%,24%and 8%.(4)The thinner the compound roof coal seam and oil shale is,the lower the abnormal degree of gas emission is.(5)The high-level boreholes for gas drainage at the upper corner of the coal face is proposed.The final position of the high-level boreholes is 8m and 12m above the coal seam roof of ventilation roadway in the 50212 and 50109 coal faces.After gas drainage,the gas concentration can be controlled at about 0.3%in the upper corner of the fully mechanized face.The research results have guiding significance for gas control of Triassic oil shale coalfield in Northern Shaanxi.