Determing Rational Sub-level Interval For Top Coal Caving Operations In Steeply Inclined And Very Thick Coal Seam

According to the characteristics of horizontal sectioned fully-mechanized top-coal cavingin steep-inclined thick coal seam in Jian gou coal mine, This paper obtained the variation ofthe mechanical parameters of top coal under different moisture content condition by themethods of theory analysis to the damage of top coal and laboratory mechanical experiments.And simulated damage and migration law of the roof and floor and stress distribution ofdifferent vertical height by the methods of physics resemble simulation and FLAC3D.Analyzed the determination of the section of the horizontal sectioned according to theory ofrectangular plate, and further weakened extremely thick and hard top coal by water injectionto ensure the smooth release of top coal and then improved top coal recovery rate, it can guidejob of top coal weakening by water injection during the production.First of all, analyzed the broken law of the roof during the interaction of normal load andtangential load, and theoretically analyzed the broken and collapse law of top coal. At thesame time, researched the influence of the roof and floor to the destruction of the top coalwhen we used the method of horizontal sectioned fully-mechanized top-coal caving insteep-inclined thick coal seam by sublevel mining model, and explored the relationshipbetween coal and rock mechanical parameters and moisture content by mechanicsexperiments.Secondly, according to coal seam geological data of Jian gou coal mine, researched thebroken and collapse law of the roof and floor and the migration law of top coal of horizontalsectioned fully-mechanized top-coal caving in steep-inclined thick coal seam by physicsresemble simulation, simulated the stress field distribution along strike and trend o f the roofand floor and the top coal of sublevel mining by FLAC3D and analyzed the stress fielddistribution of overburden and top coal, provided a basis for the determination of reasonablesection.On the basis of these, we can ensure the top coal recover y rate by changing thephysical and mechanical properties of top coal through the method of water injectionweakened, because it can change the stress distribution of the top coal. Finally, the water injection work was put into practice inhorizontal sectio n of27mfully-mechanized sublevel caving mining working face of Jian-gou coal mine by the results ofthe above study. Practice has proved that the recovery rate and the raw coal productionincreased and the amount of dust greatly reduced after water injec tion, and the effect of waterinjection is good.