Study on Coal Pillar Pressure Behavior Law of Fully Mechanized High Cutting and Top Coal Caving Mining in Shallow Mining Depth

Due to the base rock thin thickness and the dynamic loading obvious in the coal mining face,the width of the sectional coal pillars in the fully mechanized high cutting and top coal caving mining face in the shallow mining depth would be always hard to be rationally set up.With the stress sensors layout along the strike direction of the sectional pillars in the coal mining face,the paper studied the mine pressure behavior law of the coal pillars influenced by the mining full process.The coal pillars were affected by the mining operation of the coal mining face,the stress would be in an asymmetric saddle distribution and the stress variation would be beyond the advancing of the coal mining face.The stress concentration coefficient at the goaf side near the coal mining face would be higher than at the actual coal side.There was low stress zone with a width about 8 m between the two saddle type peak values which could fit the results of the dispersed element numerical simulation.The results showed that there would be a low stress zone in the coal pillar.In comparison with the plans,the rational width of the coal pillar was set as 20 m.