Three Dimensional Gas Drainage Technology of Pillarless Coal Mining in Contiguous Outburst Seams Group

In order to solve the gas content over the limit and other problems occurred in the contiguous outbursts seams group of Shaqu Mine ,the theoretical analy sis,ab experiment,site experiment and other means were applied to analyze the high gas emission value from the first coal mining face,the difficulty of the gob-side entr y retaining of the high cutting coal mining face,the gas drainage was hard to reach the target and other problems. The paper provided the three dimensional gas drainag e technology of the pillarless mining in the contiguous outburst seams group and the key technology of the gob-side entry retaining of the high cutting coal mining. The r esults showed that the technology had realized the gob-side entry retaining of the 4.2 m high cutting coal mining face. The convergence of the gob-side entry retaining was controlled below 34% and the cross section of the gateway was ensured over 8.0 m2in order to meet the requirements of the mine ventilation and the gas control. The gas drainage rate of the coal mining face reached at 71.2% and the coal mining rate was improved by 13%.