Numerical Simulation of Protective Coal Pillar Setup in Open-underground Combined Mining

In order to study the setup of the safety coal pillar in Open-underground combined mining, in Pingzhuang West Open-pit and Wujia No.4 Mine for engineering background, simulated protective coal pillar width 400m,375m,350m mining process by FLAC3D numerical simulation software, get the stress and deformation curve of the slope and the factor of slope stability in different protective coal pillar width cases. Research shows that the factors of safety are more than 1 when protective coal pillar width are 400m,375m, landslide not occur. When the slope protective pillar is 350m, slope displacement occurred by a large margin, the factors of stability in 1, 2, 3 monitoring position were less than 1, landslide will happen. So make sure the width of coal protective pillar above 350m.