Pressure Relief Mechanism and Gas Extraction Method during the Mining of the Steep and Extra-Thick Coal Seam: A Case Study in the Yaojie No. 3 Coal Mine

Gas disasters, such as coal and gas outburst overflow, always occur during the mining of steep extra-thick seam in horizontal, fully mechanized, top slice caving (HFMTCSC) method. To solve these issues guarantee safe efficient Yaojie No. 3 mine, 3DEC software was used this work to investigate overburden movement collapse law well stress redistribution coal-seam deformation characteristics below goaf. The results show that a pressure arch structure hinge are formed succession rock, which induces During upper slice, more than 75% lower is located at effective relief zone; therefore, can then be protected by slice. Meanwhile, with increase depth, range expands. Based on mechanism, crossing boreholes bedding were reasonably designed efficiently extract mine.