Technology Research For Working Face Preliminary Safe Mining In Condition Of Thick Coal Seam And Tight Roof With High Gas Content

In China,the geological condition of coal mining in total are complex and changeable,in this case,we come across many problems in mining.For example,when the hard roof high gas thick coal seam working face coming into initial mining period,it will facing some common problems like the top-coal hard to cave,the mine pressure too big when the roof broken,the gas density too high to regular work.So we take the N1101 working face of Yuwu coal mine in Shanxi province as an example.Through the methods like the theoretical analysis,the numerical simulation and the field test,we take the measure of forced caving in initial mining period to change the structure of roof,therefore the distance of roof broken range coming short,so the problem of the top-coal hard to caving and the mine roof pressure too big been resolved.In a suitable position,we make the roof high pumping lane sinking until it connected with the cutting eye,in these case we overcome the high gas.Finally,we get a technical system which can resolve the problems of high gas tight roof and thick coal seam working face during initial mining period.Through theoretical calculation,the broken range for each roof after forced caving of N1101 working face are as follow.Lower immediate roof broken range is 8.97m,upper immediate roof broken range is 17.69m,basic roof broken range is 25.13m.Field monitoring results as follow.Lower immediate roof broken range is 8m,upper immediate roof broken range is 14?16m,basic roof broken step is 24m.The result of numerical simulation is consistent with theoretical analysis and field monitoring results.Theoretical analysis show that the roof high pumping lane 's location should be put in the place where above the working face 15m.Through plastic zone development Simulate,we can get that the higher of plastic zone is 34m when the working developed 100m and the roof high pumping lane be included with plastic zone bottom,therefore we make the roof high pumping lane sinking in this distance.With field monitoring,in this distance the higher of roof high pumping lane is 37.4m,the roof high pumping lane gas extraction is 18m3/min which shown that it can working well.Studies showm that,the method of forced caving and roof high pumping lane location changing can resolve the problems of high gas tight roof and thick coal seam working face in initial mining period.