Stydy On Forced Roof Caving And Underground Pressure Regularity Of Double Hard Limestone Roof

At present more and more problems about roof of coal mining exciting in ourcountry, the most prominent is the hard roof difficult to caving, periodic weightingspace too long and periodic pressure strong. There is a hidden trouble to the safeproduction when the hard roof does not caving. Therefore, the double limeston hardroof on the15#coal of Ci LinShan coal ltd Shanxi lu’an group is studied by this paper,with field geological surveys, analysis the overburden’s litholgic, numerical simulationand industrial test, determine to control the15#coal hard roof by presplitting blasting.The feasibility and the validity are verified by hydraulic support pressure date monitorand analysis.According to the analysis, there is two hard roof in20meters of15#coaloverburden, the first hard roof is the second immediate roof which is argillaceouslimestone and the thickness is2.89meters, the second hard roof is the limestone whichis the main roof and the thickness is6.5meters. According to the monitor, withoutpresplitting blasting the periodic weighting space is35.47meters, periodic pressure isstrong. The pressure is calculated that the periodic pressure is8600KN withoutpresplitting blasting, this pressure is big than the max hydraulic support workingpressure, it is thus that presplitting blasting is necessary for the mining workface safe.The result show that, the roof of the Ci Lin Shan mine15#coal periodic pressure isstrong, use the presplitting blasting scheme can solve the periodic weighting problem tomake sure production safety.