| In rencent years,Shanxi province fully 2rectified and standardized mineral resources development order,and reorganized and intergrated many small coal mines,and changed slow and extensive production model formatted a long time ago,and built a number of high mechanization and large-scale production mines.But many integrated mine faced old mining residual coal area left by origin small coal that adopted low recovery old mining method,and recycling rate less than 30%,and a large number of coal resources were left,which could contain anthracite?coking coal and so on.That recovering these coal resources could promote the full development and rational utilization of resources and achieve resources efficient development and utilization demand,and could maintain coal industries long-term development.The paper based on secondary mining of Jinmei group Shenghua 3#coal seam old mining area,on the basis of fully studied original old mine area technical data and early revealed case of 3101 working face,and summarized the residual coal occurrence structure,and studied the stability of abandoned roadway and surrounding rock stress and deformation and control technology by the means of theory?numerical simulation and similar simulation.The main work as follows:1.Analyzing residual coal occurrence structure of Shenghua 3#coal seam old mining area,and took the structure into five types,and determined that old mining area occurrence situations mostly contained abandoned roadway and pillar.2.Applying girder theory to analyze the roof breakage case of abandoned roadway(group)in old mining area,studies as follow:When single roadway existed in front of residual working face,the maximum span was 10.8m;when roadway existed in front of residual face,the maximum roof span was 8.8m;and concluded that the minimum width of pillar was 5.5m by applying extended SMP criterion.The roadways span in Shenghua old mining area were 2m? 8m,and the left pillars width were 8m?20m,so we knew that the roadway and coal pillar kept stable before recovering.3.Applying numerical simulation to analyze roadway(group)surrounding rock stress in old mining area,when single roadway spans were 6.6m,8.7m,roadway sides stress concentration factors were 1.95,2.39,when two roadways spans were 6.6m8.7m,stress concentration factors were 1.95,2.39,so roadway surrounding rock stress concentration factor K increased with the more roadways and the larger span.4.Applying numerical simulation to research roadway surrounding rock regular with residual working face advance:in recovery progress,roadway group in front of working face didn't occur large-scale instability failure.Roof fissures developed and appeared roof fall phenomenon with working face gradually outskirted roadway;pillar and top coal formed concentrated stress,and the larger ratio between span and pillar width,the larger concentrated stress factor;stress in top coal above roadway far less than stress in top coal above pillar.5.Applying similar simulation to research residual working face regular pattern in the case of untreated roadway in old mining area.?Rock subsidence displacement reduced with the increase of rock layers,and the larger span,the larger roof subsidence displacement,and generally the maximum displacement occurred in the middle.? When residual working face attached to abandoned roadway,the greater roadway span,the easier to caving.?Residual working face basic roof caving initial span was 77cm(23.1m in reality),and the maximum collapse height was 48cm(14.2m in reality),simultaneously,support working resistance peak was 14000kN,which showed thar mine pressure beheaved strongly.?The maximum support resistance near small abandoned roadway was 10000kN,and near large abandoned roadway was 12500kN.So we knew that support working resistance occurred peak when crossing roadway,the larger span,the greater support resistance.6.Applying similar simulation to research residual working face regular pattern in the case of prefilling roadway in old mining area:?When residual working face attached to abandoned roadway,prefilling effectively controlled roof displacement diversification,and did not occur deformation and failure.?Residual working face basic roof caving initial span was 70cm(21m in reality),and the maximum collapse height was 35cm(10.5m in reality),simultaneously,support working resistance peak was 8700kN.?The maximum support resistance near small abandoned roadway was 6800kN,and near large abandoned roadway was 8000kN.Comparised with untreated abandoned roadway,prefilling could effectively reduced support resistance,and could actively control roadway surrounding rock in the front of working face and moderate mine pressure behavior. |
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