Study on protective coal pillar left design method of mine shaft based on solid backfill mining

In order to solve a rational left problem of the protective coal pillar in the mine shaft when a solid backfill mining was applied torecover the coal pillars under the surface industrial park,according to the failure features of the mine shaft,an analysis was conducted onthe main factors affected to the mine shaft failure under the cond ition of a compact rate,size of the protective coal pillars in the mine shaftand other backfill mining conditions. The protective coal pillar left principle of the mine shaft was p rovided based on the compact rate con-trol. Based on the circumstances,an analysis was conducted on a vertical profile method,Kowarzik probability integral method,ABA QUSnumerical simulation method and other protective coal pillar left method of the mine shaft. A comprehensive left method and design processof the protective coal pillar in the backfill mining shaft was established with profile method to set up the coal pillar boundary and the theo-retical calculation and numerical simulation combined to stea dily reduce the boundary. This method was applied to the backfill mining andrecovery of the coal pillar project under the industrial park of Baishan Mine and the protective coal pillar division of the mine shaft underthe different compact rate condition was obtained. The results showed that the compact rate of the solid backfill mining could be C ontrolledover 80%. Based on a coal pillar calculation of the mine shaft with a left radius of 154 m,the coal under the industrial park at less couldbe safely released with a co al resource of 1.745 million.