Study Of Rational Width Of Chain Pillar Of Extremely Thick Coal Seam In Datong Mining Area

The Permo-Carboniferous 3-5^#extremely thick coal seam,whose average thickness is 16.8 meters,is the main mining coal seam in datong mining area.The datong mine field sets large coal pillar for its huge coal reserve,which leads to coal resources wasted seriously,mine and layer is influenced by igneous,the strata-pressure behaves different in different mining area.Based on the background of different horizon of coal and rack was invaded in different mining area in Tashan mine,the paper majorly study on the rational width of coal pillar?the width of pillar between roadway,the width of pillar of end-line mining?in different type of overburden strata.The paper made further study on the internal stress of end coal pillar,vertical stress and abutment pressure distribution of around roadway with different overburden's types,and study the influence of overburden structure in end mining to the end-line mining coal pillar.The paper used the major research method includes theoretical research,numerical simulation and similar simulation.The results shows as follows:Firstly,the paper studied the stability of chain Pillar using theoretical research.The reason of instability coal pillar between roadways dues to the plastic extended to the deep coal pillar,which made the pillar capacity gets weak.The reason of instability end-line mining coal pillar dues to the result of the strength of surrounding rock exceeds its limit because the abutment pressure keep passing forward.Secondly,the paper simulated the rational width coal pillar between roadways based on the geological condition that different horizontal stress and different horizon coal and rock intruded by igneous was disturbed with different coefficient vertical stress using FLAC^3D numerical simulation software,and the result shows that the minimum width of pillar is 20 meters.Thirdly,the paper studied the structure morphology of extremely thick coal seam key stratum with the stope mining using similar simulation test.The paper shows that when the high and low key layer breaks at the same time,the stress of end-line mining coal pillar gets higher markedly,and the stress of surrounding rock gets high suddenly;The paper established mechanical model of low key layer,and studied the elastic zone stress distribution characteristics of end-line mining coal pillar by the beeding deflection of rock beam.Finally,the Flac^3D numerical simulation software was applied to explore the reasonable width of end-line coal pillar in extra-thick coal mining with different overburden's types.The internal stress of end coal pillar,vertical stress and abutment pressure distribution of around roadway with different overburden's types were analyzed emphatically,and made deep analysis to the difference reasons of width coal pillar,the stress of coal pillar and lead abutment pressure.With the increasing of hard layers formed by intruded igneous,the width of pillar is smaller.The result of numerical modeling shows that the width of end coal pillar without igneous intrusion is 150 m,the width of end coal pillar with three layered igneous is 135 m.The study can provide some significant references for the determination of end coal pillar's width and the monitoring of stress around roadway for the designation of chain pillar of extra-thick coal seam in datong mining area.