Study On Optimization Of Mining Pillar In Isolated Island Working Face Of Thick Coal Seam Under Complex Conditions

In this paper, a thick coal seam in Shandong Province is used as a prototype, which is located below the upper layer of 6 m residual pillar, and is a typical isolated island coal face based on the mining theory of upper liberation layer. The optimization study on the coal pillar of the island coal pillar working face formed by the ower stratification is carried out. When mining the coal face with stratified island pillar, it is easy to be affected by the upper residual coal pillar and the lateral support stress of the two side goaf. The isolated island surface is easy to form high concentration stress, the roof movement is violent, the impact ground pressure is easy to be induced, and the support press frame is easy to be formed. Mining earthquake and other dynamic disasters seriously threaten the safety of working face. Therefore, the reasonable determination of the width of coal pillar is guaranteed. By using UDEC numerical simulation method, this paper studies the mining optimization of the coal face under the influence of the upper stratified residual pillar, which is the important factor of the safe mining of the separated island working face under the thick coal seam, and the optimization of the mining of the coal face under the influence of the upper stratified residual pillar. This paper analyzes the stress distribution and evolution law of coal pillar in lower layer protecting roadway, and determines that it is appropriate to keep 12 m coal pillar in isolated island working face of lower stratified coal pillar, and the internal dislocation is 6 m in the residual pillar of upper stratification, which can reduce its impact risk at this time. It can ensure the safe mining and high recovery rate of coal.