Failure Characteristic of Residual Coal Pillar and Its Influence on Downward Mining

Taking Wangfeng Colliery as an example,this paper applied Wilson coal pillar design method and limit equilibrium condition to analyzing elastic-plastic deformation area of residual coal pillar after mining with wedge pillar method and calculating limit loading on coal pillar.Result shows that actual loading on pillars in 8th Coal Seam is smaller than limit value and pillars are stable.Stress concentration due to overlying strata weight on pillar will make downward coal seam mining difficult.