Researches On Mined Rockmass Failure Features And Gas Seepage Evolution Law With The Upper Protective Layer Mining And Its Application

The Dengfeng mine area gas storage geology characteristic and level control gas-geology rule were analized. The protective layer mining conditions in the Dengcao mine were demonstrated. Based on the mine pressure theory, dynamic failure process and coupled gas-solid interaction between gas flow and solid deformation, the stress variation law, roof and floor deformation, fracture evolution law, displacement in the protected seam, change in gas permeability and gas flow law during upper protective layer extraction were studied. A large number of abscission layer cracks and trans-layer cracks were produced in pressure relief expansion of the protective layer to make gas desorbed. Under the gas pressure, the desorbed gas flow to the goaf through the cracks to eliminate the gas outburst risk of protected layer. The coal and rock failure and strata movement process were affected by the Young’s modulus, internal friction angle, tensile strength and Theological properties. The mermal effects in the rockmass damage-strain-failure were studied. The effective measures were taken to detect gas coal layer and geological structure to prevent the gas outburst of protected layer. The method of gas sources control was proposed through measuring and analyzing gas emission sources during tunnel excavation process. Field test results showed that measures were safe and effective in fast driving. So the methods could be used in controlling gas outbursts under the similar conditions.