基于底板岩巷全生命周期瓦斯治理技术研究

Research on full-life cycle gas treatment technology based on floor rock roadway

  • 摘要: 对于缺乏开采保护层条件的矿井,底板岩巷条带预抽煤层瓦斯是主流瓦斯治理方法。分析指出底板岩巷在实际应用中存在空间层位选择差异较大、 穿层冲孔致煤巷围岩稳定性差、底板岩巷掘进造价高且利用效率低等问题。以底板岩巷为基础,考虑整个煤炭生产过程中的瓦斯问题,提出了基于底板岩巷全生命周期瓦斯治理技术,形成了“层位优选−穿层冲孔−穿层注浆−采动抽采−矸石回填”五位一体的瓦斯综合治理模式。以首山一矿为例,通过测定采煤工作面地层的岩石力学性质,基于数值方法分析了巷道掘进和工作面回采条件下底板岩巷的稳定性,根据围岩损伤特征和采动围岩应力分布,确定了将底板岩巷布置在采煤工作面运输巷下部16 m、与上部运输巷内错1 m位置。对底板岩巷穿层水力冲孔钻孔布置进行优化,设定了组间距6.4 m、每组按单双号交错打孔的方案,通过测定水力冲孔钻孔残余瓦斯压力得出水力冲孔有效影响范围超过4 m,钻孔瓦斯浓度较高、衰减较慢,条带预抽效果良好。通过穿层注浆技术改善上部破碎煤体性质,钻孔窥探显示经过穿层注浆加固后的煤体强度提高、破碎程度降低,巷帮变形量监测结果表明巷道围岩整体稳定性较好、煤层强度提高,钻屑量监测结果表明注浆加固范围超过5 m,有效降低了巷道掘进的突出危险性。通过底板岩巷穿层钻孔,对工作面回采期间采动卸压瓦斯进行抽采,发现采动有效影响范围为采煤工作面前方50 m,采动影响区内瓦斯抽采效果良好,采煤工作面风流瓦斯体积分数降低至0.45%以下,有效降低了采煤工作面瓦斯浓度。回采结束后,设计了底板岩巷矸石回填方法,以降低矸石出井成本,提高巷道利用效率。

     

    Abstract: For mines lacking conditions for mining protective layers, pre extraction of coal seam gas from floor rock roadway strips is the mainstream gas control method. The analysis indicates that there are problems in the practical application of the floor rock roadway, such as significant differences in the selection of spatial layers, poor stability of the surrounding rock of the coal roadway caused by through layer punching, high excavation cost, and low utilization efficiency. Based on the floor rock roadway and considering the gas problem throughout the entire coal production process, a full-life cycle gas treatment technology based on floor rock roadway is proposed. It forms a five-in-one gas comprehensive treatment model of "layer optimization, through layer punching, layer grouting, mining extraction, and gangue backfill". Taking Shoushan No.1 Coal Mine as an example, by measuring the rock mechanics properties of the strata in the coal mining face, the stability of the floor rock roadway under the conditions of roadway excavation and mining face is analyzed based on the numerical method. Based on the characteristics of surrounding rock damage and the distribution of stress in the mining surrounding rock, it has been determined to arrange the bottom rock roadway at a position of 16 meters below the mining face transportation roadway and 1 meter inboard from the upper transportation roadway. The layout of hydraulic punching holes in the floor rock roadway is optimized. The group spacing is set to be 6.4 meters. The interleaving drilling is arranged by odd and even numbers for each group. By measuring the residual gas pressure of hydraulic punching holes, it is found that the effective influence range of hydraulic punching holes exceeds 4 meters. The hole gas concentration is high and the decline is slow. The strip pre-extraction effect is good. The though layer grouting technology is used to improve the properties of the upper broken coal body. The drilling observations show that the strength of the coal body after through layer grouting reinforcement is increased and the degree of fragmentation is decreased. The monitoring results of the deformation of the roadway side show that the overall stability of the surrounding rock of the roadway is good. The strength of the coal seam is increased. The monitoring results of the amount of drilling debris show that the grouting reinforcement range exceeds 5 meters, effectively reducing the risk of outburst in the roadway excavation. Through drilling through the floor rock roadway, the pressure relief gas extracted during the mining process of the working face is extracted. It is found that the effective influence range of mining is 50 meters in front of the coal working face. The gas extraction effect in the mining-affected area is good. The gas concentration in the air flow of the coal working face is reduced to below 0.45%, effectively reducing the gas concentration in the coal mining face. After the completion of mining, a method of backfill gangue in the floor rock roadway is designed to reduce the cost of gangue extraction and improve the utilization efficiency of the roadway.

     

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