Study On The Ascending Mining Technology Of The Closed Distance Coal Seams Under The Condition Of The Underlying Thick Coal Seam With Fully Mechanized Caving

To improve the coal recovery rate,extend the mine service life and realize the reasonable mining between the thick coal seam and the thin one,the feasibility study of ascending mining technology(AMT)was carried out under the condition of the closed distance coal seams which contained the underlying thick coal seam with fully mechanized caving(CUFMC).Based on the geological conditions of the CUFMC in Yanjiahe Coalmine(YC),the AMT under this condition was further studied by a combination of theoretical analysis,physical simulation,numerical simulation,and field research.Based on the migration law and fracture characteristics of the overlying strata on the No.8 coal seam,the failure characteristics and deformation law of the overlying strata,the ascending mining feasibility and the key parameters of face arrangement in the No.5-1 and No.5-2coal seam were determined to ensure the safe and efficiency mining in the CUFMC.Innovative achievements of the thesis have been displayed as follows:(1)The theoretical result shows that the No.5-1 coal seam is located in the upper position of caving zone and the lower position of the fracture zone of the No.8 coal seam,but the No.5-2coal seam is located in the transition position between fracture zone and its caving zone.Some the drilling regions does not meet the requirement of the AMT.(2)The analysis of migration law and fracture characteristic of the overlying strata shows that the height of caving zone of No.8 coal seam is about 25 m and the height of its fracture zone is 35 m to 60 m.The No.5-1coal seam is above the caving zone,so the roof and floor don't appear the step diastrophism which means thatthe integral continuity is relatively good.So,the AMT can be carried out.The No.5-2coal seam is located in the transition position between the fracture zone and caving zone,so it is badly destroyed.(3)Observation drilling test shows that the caving zone hight of No.8 coal seam is 16 to 26.7 meters.Tunneling prospecting shows that the No.5-2 coal seam is integral sinking,whose roof and floor have no step diastrophism with the integral continuity relatively good.So,the AMT can be carried out.When the entity coal seam or the wide coal pillar(>20 m)is beside the goaf of No.8 coal,seam,the transportation tunnel of the No.5-2coal seam should be at least 25 m far away within the No.8 coal goaf.(4)To sum up,under the condition of fully mechanized caving,the overlying No.5-1 and No.5-2 coal seams is integral sinking,which means that the overlying strata is in a good condition and no step diastrophism apears in the No.5-1and No.5-2coal seams.The AMT is feasible,except for the cut-hole,the stopping mining line and the upper and lower position of and the upper part of working face.