To improve the coal recovery rate

it is crucial to properly determine the coal pillar size

supporting patterns and parameters of the roadway

since this can ensure the stable of butt entry with fully-mechanized mining. The evolution of principal stresses

deformation and failure are studied using FLAC3D with different pillar widths in haulage roadway 20103 of Wangjialing coal mine. It is shown that the most reasonable and economic pillar widths range from 6 m to 10 m. The final reasonable pillar width is determined to be 8 m based on the geological production conditions. Theoretical analysis and borehole observation show that the main roof breaks at 7 m next to the gob. The property and structure of the surrounding rock and the stress distribution are asymmetric along the axis of roadway

resulting in asymmetric roof strata behaviors including the subsidence of roof near the pillar and even the dislocation

embedding

step convergence of rock on the abutment of coal mine. The roof near the pillar and the abutment of coal mine are the key positions of deformation failure. A comprehensive supporting technology is proposed including high strength anchor-beam-net

asymmetric cable-beam and cable truss. The mechanism of supporting measures for surrounding rock is analyzed. It is shown that the pillar width with 8 m is reasonable and the proposed measure can control the asymmetric deformation failure. The proposed supporting measure has been successfully applied to Wangjialing mine area.