近距离煤层群中煤组瓦斯集中治理技术研究

Study on Gas Centralized Control for Mid-coal Measures in Close Coalbed Group

土城矿属于煤层群开采,各主采煤层均具有突出危险性,首采保护层回采期间面临着瓦斯突出和涌出量超限2大难题,故提出中煤组集中瓦斯治理技术。根据煤层覆存条件合理选择首采层,可对上覆及下伏煤层有效卸压;保护层顶、底板裂隙带最大发育深度分别为58.9、31.7 m,在保护层回采期间,中煤组各临近层瓦斯均会涌入生产空间。施工穿层长钻孔对首采面及临近层进行瓦斯集中抽放具有显著效果,钻孔有效抽采半径的理论值为2.5 m。对中煤组瓦斯浓度、流量监测结果归一化处理,得到首采层瓦斯抽采比例占整个中煤组的30.6%,预抽300 d时抽采量约5.5×106m3,并可有效降低回采期间邻近层瓦斯涌出量。

Tucheng coal mine belongs to coalbed group mining, and each main coalbed has outburst risk. During the first mining of protective layer, there are two major problems of gas outburst and emission exceeding the limit. Therefore, the centralized gas control technology of middle coal group was proposed. According to the coalbed occurrence conditions, optimal selection of the first mining layer can effectively relieve the stress around the overlying and underlying coal seams;the maximum fracture zone depth at the top and bottom of the protective layer are 58.9 m and 31.7 m respectively, which indicates the gas in the adjacent layers would flow into the production space. The theoretical value of effective drainage radius is 2.5 m. Through the normalization of gas concentration and flowrate results,the gas drainage proportion of the first mining layer accounts for 30.6% of the whole middle coal group,and the drainage amount is about 5.5 million cubic meters when the pre drainage is 300 days.Moreover, this method can also effectively reduce the gas emission of adjacent layers during the mining period.