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某矿三水平阶段运输大巷掘进过程中,前方有瓦斯积聚的近距离煤层群A3-2煤层、A3-1煤层、A5煤层导致了掘进的危险系数增加。在揭露A2煤层过程中实施钻孔预测而钻孔岩石段出现了喷孔现象,借助于瓦斯现场监测及地质资料分析相关喷孔原因,并提出了集中布置预抽钻孔实施3层近距离煤层的提前预抽,得出了以下结论:掘进中煤线附近瓦斯涌出及炭质泥岩变质的瓦斯涌出,导致岩石段喷孔;在揭露极薄煤、矸混合的煤线时,以测定钻屑瓦斯解吸指标K1值为标准,在进行突出危险性判断时,取日常临界值的70%~80%作为其临界值;在揭煤前应实施超前集中布置的预抽钻孔,进行A3-2、A3-1、A5煤层的瓦斯提前集中预抽,降低了石门揭煤的工程量及危险系数。
In the process of tunneling of a three-level transport tunnel, the A3-2, A3-1 and A5 coal seams with gas accumulation in front of the mine lead to an increase of the danger coefficient of driving. In the process of exposing the A2 coal seam, the drilling prediction was carried out and the hole injection occurred in the rock drilling section. With the help of gas field monitoring and geologic data analysis, the reasons of the injection holes were analyzed. , The following conclusions are drawn: The gas emission near the coal line during the excavation and the metamorphic gas emission from the carbonaceous mudstone lead to the jetting of the rock section. When the coal line with extremely thin coal and rock mixed is exposed, The K1 value of desorption index of cuttings gas is the standard, and 70% ~ 80% of the daily critical value is used as the critical value when judging the prominent danger. Before the coal uncovering, pre-drill holes arranged in advance shall be implemented to carry out A3 -2, A3-1, A5 pre-pumping gas concentration ahead of schedule to reduce the amount of stone cross-cut coal and dangerous coefficient.