为确定顺层瓦斯抽采钻孔封孔长度,基于煤层内开挖巷道后巷道周围的应力分布情况,煤层渗透率与煤体所受应力的关系,以及流过煤体的气体流量与煤层渗透率变化规律,提出了“稳压测流量”法测定煤层巷道松动带的范围,分析了该方法在理论上的可行性,并依据该测定方法的原理,设计出了该测定方法的设备.在薛湖煤矿进行了现场试验,根据测定结果,发现随封孔位置的深入,注气稳定流量均呈衰减趋势,直至一定封孔深度,气体流量趋于稳定.在松动带范围内,气体的流量较大,虽有衰减,但衰减的幅度不大,均为21％ ～26％;松动带过渡地带,随着钻孔的深入,裂隙急剧减少,稳定流量急速衰减,衰减量为71％～82％,这两个区域裂隙较多,不适于封孔抽采,而在10.5 rn以内,裂隙发育趋于稳定,达到最小值,可进行封孔抽采.依据测定现场进行了不同封孔距离下的抽采效果考察,发现依据测定的松动带范围封孔,能显著提高抽采浓度,增加钻孔寿命,解决封孔长度不科学造成的漏风问题.%In order to determine drilling sealing length of gas drainage with horizontal drill bore,based on the stress distribution around coal roadway and the relationship between permeability of coal seam and strain on coal-body after tunnel excavation in coal seam,theoretical analysis on the law of gas flow through coal-body which change with permeability of coal seam,"Constant pressure flow measurement" had been put forward to determine relaxation zone scope of coal roadway.The feasibility of the method had been analyzed in theory and the equipment for the determination had been designed according to the principle of the method.A field experiment was conducted in Xuehu Coal Mine,according to the measured results,steady gas injection flow suffers from attenuation gradually along with the rising on sealing depth;the gas flow appears to be stabilizing while the bore sealing reaching a certain depth.Although the attenuation,but at a modest rate within a range of 21％ to 26％,the gas flow rate was much lager in the relaxation zone.However,the fractures reduced sharply along with the rising on drilling depth and steady flow reduced at a large rate within a range of 71％ to 82％ in the transition to relaxation zone.These two regions was not suitable for sealing drainage due to much more fractures.However the development of fractures was stabilizing in the scope of 10.5 meters,drainage was workable.Drainage effect was investigated at site based on different bore sealing depth.It turned out that the drainage concentration and bore life increased while bore sealing conducted on the basis of measuring relaxation zone.The problem of air leakage due to the unscientific bore sealing depth had been solved.
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