Small Pillar Driving Technique in Fully Mechanized Working Face of Outburst Coal Seam

Abstract

Aiming at the safety problems caused by poor roadway stability and other factors during gob-side entry driving of 15106 isolated island face in Sijiazhuang Mine, theoretical calculations, numerical simulations and field tests were adopted to determine the coal pillar size and field practice effect of gob-side entry driving in isolated face. The results show that there are key blocks in the lateral structure of the overlying strata on the isolated face that affect stress distribution. Through analysis and calculation, there is a critical value for the coal pillar size for gob-side entry driving. When the size of coal pillar exceeds this value, the stress of coal pillar increases significantly, this is not conducive to the stability of stoping roadway. Through numerical simulation and field test of coal pillar lateral stress distribution, combined with mining safety analysis, the coal pillar size of 15106 isolated island face in Sijiazhuang Mine was determined to be 7 m. After the gob-side entry driving with small coal according to the determined coal pillar size, the maximum approach amount of the top and bottom plates is about 324 mm, and the maximum approach amount of the two groups is about 224 mm, which are 42% and 29% lower than those when gob-side entry driving method is not used. The maximum concentration of return gas is 0.35% and the average is 0.15%, the amount of anti-outburst drilling works decreased by about 2/3, and the average monthly footage of the 15106 face into the return air lane increased to 2.35 times of the average monthly footage of the original coal body.

Keywords

• isolated island face
• gob-side entry driving
• small coal pillar
• coal pillar size
• stress distribution