Investigation and analysis of coal-gas outburst accident induced by overlapping mining stress

Coal-gas outburst occurred on the headentry driving face of 11041 air intake in Malingshan coal mine, Zhengzhou Coal Co. Ltd, China, at about half past 18 on February 10, 2006. The mass of jetting coal was 339 tons, gas 28 341 m(3), and 15 persons lost-their lives in this calamity. On-the-spot investigation showed that the headentry driving face located in overlapping concentrated stress zones caused by the coal pillars, which were left behind after underlayer A(7) coal bed had been mined in Malingshan coal mine. When tunneling along the floor, the dropping of coal body from the upper roadway increased the risk of coal-gas outburst. So stress concentration and coal body dropping were.the key factors of the accident. When deep hole was drilled, the balance of the stress was destroyed, and then the accident of coal and gas outburst was induced. In addition, the incomplete ventilation system was the important reason why the number of deaths increased after the coal-gas outburst accident happened.