Protection scope and gas extraction of the low-protective layer in a thin coal seam: lessons from the DaHe coalfield, China

Aiming at promoting thin coal seam pressure relief gas extraction, as well as delimiting the protection range of the low-protective layer in thin coal seam, in this paper, we simulated the changing process of the protective layer stress field and deformation field during the low-protective layer mining and obtained the characteristics of the displacement as well as the stress varied characteristics of the overlying strata in the low-protective layer mining. According to the protection layer mining stress relief and the deformation protection criterion, the tendency and trend of the protection layer protection scope were determined, and the theoretical calculation results were basically consistent with the direction protection angle of the protected coal seam. Taking the Dahe (DH) coalmine as an example, the floor rock roadway as the gas drainage roadway to extraction gas as well as the scheme of gas extraction and pressure relief in the upper and lower layers of the protective layer were implemented. The effect of gas control scheme showed that the working gas concentration reached the mining requirement. We finally established the low-protective layer in thin coal mining integrated technical scheme of protection scope and pressure relief gas extraction.