Overlying Rock Failure and Deformation of Lower Protective Coal Seam Mining in No. 10 Mine of Pingdingshan

According to the occurrence characteristics of F_15-16 coal seam in No.10 mine of Pingdingshan, the stress distribution characteristics, released range and deformation law of protected layer in the process of near distance and lower protective layer mining were analyzed by adopting similar material simulation, digital speckle and numerical simulation. The results showed that the protected layer was located in the middle and lower part of fractured zone after the protective layer mining, and the pressure was fully released. The rate of maximum swelling deformation reached 1.91%, and the protected scope of protected layer was inward migration 8 m to 10 m towards the trend direction and inward migration 8 m to 11 m towards the inclined direction. The protected layer generated the expansion deformation which makes the permeability increase, created the condition of simultaneous extraction of coal and gas. The scheme of pressure relief and gas extraction was determined.