Study on mechanism and control of strong ore pressure in mining thick coal seam under goaf in close coal seam
Aiming at the phenomenon of strong ore pressure on the top of W1701 working face of thick coal seam under in close coal seam goaf,the induced mechanism and control measures of strong ore pressure on the top of W1701 working face under the condition of full thickness mining at one time are studied by physical similarity simulation experiment,theoretical analysis and numerical simulation experiment.The results show that the roof of W1701 working face is affected by the overlying rock structure breaking movement of"high key layer(hard rock)and extremely thick weak rock group and low key layer(hard rock)"above it,the roof presents large and small periodic pressure changes,in which the"masonry beam"of the low key layer is structurally unstable and forms small periodic pressure.The longitudinal cracks of the extremely thick weak rock group are periodically broken through and step subsidence occurs to form a large period of pressure,which causes a jump in the supporting pressure of the roof of the working face.The support load is as high as 67 248 kN,which is 3.7 times the rated working resistance of the support.It is easy to crush the entire working face support and cause major production safety accidents.For the thick coal seam under the goaf of such close multi-coal seam in Zhunnan Coal Mine,and it is not suitable to adopt single mining with full thickness,instead,it is suitable to adopt stratified mining,which makes the extremely thick weak rock group between the high and low key layers produce fractional failure,and the pressure of the working face is greatly eased compared with the full thickness of a single mining,which can effectively avoid the strong ore pressure accident of the working face.
goaf in close coal seamstrong ore pressurethick coal seamextremely thick weak rock groupore pressure control
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