Numerical Simulation for Size of Coal Pillar of Large Mining Depth Along Gob-side Entry Driving Direction

In order to determine a reasonable coal pillar size suitable for large mining depth gateways, numerical simulations are carried out for the coal pilar of different width. Analysis and comparison are made for the stress distribution of the surrounding rock of roadways, and for the deformation and the plastic failure zones to study the stability of the coal pillar. The results show that the coal pillar internal stress peak distribution is an important factor for determining the reasonable width of the narrow coal pillar along the gob-side entry driving direction, the retained size of the pillar should be determined in a way to avoid a too high stress peak value. When the width of the coal pillar is 6-8m, the stress peak value under the pillar is not large, the displacements of the roof, the floor and two sides are small. Therefore, the pillar is relatively stable, the maintenance of the gateway becomes easy and the recovering rate is enhanced. At the same time , the coal mine production safety is easy to maintain. The application of this method offers a way for determining the reasonable size of the narrow coal pillar along the gob-side entry driving direction.