基于钻孔瓦斯流量和压力测定有效抽采半径

为了准确的测定有效抽采半径,提出基于钻孔瓦斯流量和压力的测定方法。以抽采钻孔影响范围内残余瓦斯压力小于0.74 MPa且预抽率大于30%为指标,基于钻孔瓦斯流量的负指数衰减规律,推导出有效抽采半径计算公式,并结合瓦斯压力变化共同确定有效抽采半径。该方法应用于区域预抽消突钻孔布置中,分析了不同预抽时间下的钻孔有效抽采半径和极限抽采时间,并依据预抽90 d有效抽采半径为2.5 m,布置消突钻孔。残余瓦斯压力和预抽率的检验以及煤巷掘进期间的区域验证,均证明按该方法布置的预抽钻孔,消突效果有效。

Measurement of Effective Drainage Radius Based on Gas Flow and Pressure of Boreholes

In order to measure effective drainage radius exactly,we propose the method based on gas flow and pressure of boreholes.Under the index of remnant gas pressure less than 0.74 MPa and pre-drainage rate more than 30%,the computing formula is deduced based on the negative exponent attenuation law of gas flow,and the effective drainage radius is determined in combination with the variation of gas pressure.The method is applied in the arrangement of zonal pre-drainage boreholes.The effective drainage radius of different pre-drainage time and the utmost pre-drainage time are analyzed.Based on the premise that effective drainage radius reaches to 2.5 m in 90 pre-drainage days,the boreholes are designed to eliminate coal and gas outburst.The measurement method is demonstrated valid in outburst elimination by the examination of remnant gas pressure,pre-drainage rate and the zonal verification during the coal roadway driving.