Pillar Size Determination and Panel Layout Optimization for Fully Mechanized Faces in Shallow Seams

The extraction of shallow seam with thin bedrock is characterized by roof caving vertically along the edge of the goaf,accompanied by rapid surface subsidence and goaf compaction.In this paper,taking the actual conditions of Seam 3-2 in Wenjialiang coal mine of Ulan mining group,Erdos for example,by using theoretical analysis,numerical simulation and field observations,et al,it is concluded that the reasonable width of chain pillar for gob-side entry driving is 5 m,and the goaf will gradually reach a stable state at about 50 m behind the face.Consequently,gateway layout optimization by combination of pillar entry protection and gob-side entry driving is proposed under the condition of ensuring the face mining supersedure in order.Field application demonstrates that the entries along both the goaf and solid coal can be maintained stably during the mining operation,thus making the coal recovery rate of working face increased by 13%.