Optimized Study on Coal Pillar Width of Fully- Mechanized Coal Face in Medium Thick Seam with Shallow Depth

In order to improve the coal mining rate under the mine safety mining and high efficient conditions, based on the analysis on the mine geological informa tion, the numerical simulation, theoretical analysis and site observation means were applied to optimize the coal pillar width of the coal mining face in medium thick sea m with shallow depth. The analysis showed that with the coal pillar width continuously increased, the gateway deformation value, coal pillar deformation value and coal pillar stress in the coal mining face would be steadily decreased. When the coal pillar width was 16 m, the gateway and the coal pillar would be stable basically and the deformation value would be small. During the mining process of the coal mining face with the 16 m wide coal pillar, an observation analysis was conducted on the worki ng resistance of the powered supports applied in the coal mining face and the gateway deformation value. The results showed that the average working resistance of th e powered support applied in the coal mining face was only 70% of the rated working resistance, the max value of the lateral deformation in the coal pillar of the gatewa y was 153 mm and the safety and high efficient mining of the coal mining face could be ensured based on the coal resources highly caved.