Abstract：Gas of coal mine is one of the most hazardous problems in coal industry of the world. In China，the lower permeability of coal is the main character which limits the development of gas extraction industry. In this testing study of gas extraction from low permeability coal，the big coal samples(500 mm×500 mm×500 mm) are used. There are many pores and fractures in these samples. While the coal mass is under fracturing，the gas outbursts intermittently. This phenomenon is never reported in articles before while small samples had been used. So we can conclude that when big samples are used，each sample can contain more information which leads to the experiment result closer the in-situ rock test. The experiment results also reveal that to release the initial earth stress is a better way to improve the permeability of coal. Water fracturing method is one of the efficient methods to release the initial earth stress.
杨 栋 冯增超 赵阳升. 大煤样瓦斯抽放试验研究及尺寸效应现象*[J]. 岩石力学与工程学报, 2004, 23(S2): 4912-4915.
Yang Dong，Feng Zengchao，Zhao Yangsheng. Testing study of Gas outburst in Big coal sample and phenomenon of dimensional effect. , 2004, 23(S2): 4912-4915.
7 Zhao Yangsheng，Kang Tianhe，Hu Yaoqing. Permeability classification of coal seam in China[J]. Int. J. Rock Mech. & Min. Sci. & Geomech. Abstr.，1995，32(2)：328～333
2004, Vol. 23 
