A Simplified Calculation Method for Ultimate Mining Dimension in Thin Coal Seam

Coal seam mining is one of the most widely participated engineering activities in China. This study examined the failure process induced by underground thin coal seam mining of Wangxia perilous rock in Chongqing, China. Numerical simulation was conducted on the stress, displacement and plastic deformation with Fast Lagrangian Analysis of Continua 3D (FLAC 3D ). Results show that tensile stress is dominant and it keeps increasing during coal mining. The stability failure process experiences four stages from the perspective of crack propagation. A new simplified subsidence prediction method was proposed for quick engineering applications. The relationship between mining geometric parameters and rock mass stability was established and the ultimate mining dimensions were suggested. The simplified method was demonstrated to be reliable.