【正文】 6俞啟香 礦井瓦斯防治 中國礦業(yè)大學(xué)出版社1992。在C13煤層瓦斯排除后，C13煤層的瓦斯量有效降低，％以上。當(dāng)保護(hù)工作面超前過去400米的壓力孔測量，保持穩(wěn)定，這表明。瓦斯抽放2080天之間的時(shí)期是活躍的時(shí)期，壓力活動(dòng)和滲透率達(dá)到了最大。開始，我們在C13煤層頂板和地板鉆一個(gè)鉆孔來看是否變形，然后安裝測試點(diǎn)由兩個(gè)試驗(yàn)點(diǎn)的相對位移。每個(gè)鉆鉆場沿著減壓區(qū)的方向打4個(gè)鉆，每個(gè)鉆的間距是40m，它被安置在煤層厚表層的中間?；诿簩訔l件和具體的地質(zhì)條件，巷道在C13煤層以下10～20米較好的巖層里布置或在C13煤層以上46～56米較好的巖層。當(dāng)然，.，氣體量減少到低于6m179。/ t，～l㎡/(MPa178?！?3176。通常,煤層的低滲透系數(shù)低，例如,平均來說,～1m2/()，它目前最大的困難在提前排出瓦斯控制在煤層中發(fā)生瓦斯突出。為了能夠有效地釋放瓦斯壓力，消除瓦斯突出的風(fēng)險(xiǎn)，我們使用一個(gè)特定數(shù)量的滲透鉆孔抽瓦斯。 engineering application1 IntroductionWith an increase in mining depth, the amount and pressure of gas increases, gas disasters are being more serious and several shallow and nonoutburst coal seams are gradually being outburst coal seams. Today, China has bee the country with the most serious coal and gas outburst disasters in the entire world. Globally, our frequency and intensity of outbursts are the most severe. In contrast, coal and gas outbursts coal mines had been stopped production in the USA, Australia, Russia and other countries. According to a statistical analysis by expert consultants in 2005, among 415 coal mines of the 45 major monitored state owned coal enterprises, 234 mines are high gas and outburst coal mines, accounting for % of the major coal mines and 142 mines are subjected to coal and gas outbursts, accounting for %.Usually, the permeability coefficient of outburst coal seams is low. For example, on average, this coefficient in the C13 coal seam of the Huainan ore area was only m2/(), which presented great difficulties in predrainage of gas and in gas control to prevent outbursts in coal seams. Based on the current condition of coal seams in the Panyi coal mine, we adopted a protective layer in our mining technology to drain pressure relief gas from protected seams,using RC net penetration boreholes in floor roadways, effectively reducing its gas content, pletely eliminating the danger of outbursts and achieved safe and highly efficient mining conditions.2 General situation of test areaThe Panyi coal mine is a large mine designed for 3Mt production capacity. The C13 coal seam is one of its primary and most productive coal seams, which contained a large amount of gas under high large number of outburst accidents have formerly occurred during mining, including a major gas explosion, so control over coal gas was very urgent before we could exploit this coal seam.The test area was located between the East1 and East2 mining areas, with the B 11 coal seam as a protective layer. We planned to bine mining the 21511 working face in East1 and the 23521 in East2 and called the bination 23521 instead The strike of the face is 1640 m and the trend 190 thickness of the coal seam is between ～ m, m on average and the dip angle 60130, 90 on average. The amount of gas of the B11 coal seam is , designed for 2000 t/d.The C13 coal seam is a protected layer, located 70m above the B11 coal seam. The corresponding test working face of the protected layer consists of the 21213 working face in East1 and the 23223 in East2 (called 21213/23223 bined). The strike is 1680 m (two faces in all) and the trend is 160 coal seam is ～ m thick, m on average,the dip angle 60～130 and 90 on average. The original measured gas pressure was MPa, the amount of gas (). The coal seam was also stable and its geological structure simple. By draining the pressure relief gas, the danger of outbursts in the C13 coal seam could be eliminated and the amount of gas was effectively prehensive，mechanized cover caving coal mining technology been adopted for this working face, which was signed for 5000 t/d.3 Drainage principle of pressure relief gasDraining of pressure relief gas is referred to as protective layer mining technology. When we mine coal seams in outburst coal mines, we should first mine the nonoutburst or low risk outburst coal seams as protective layers, where the outburst coal seam is then called the protected layer. With protective layer mining, the coal and rock mass among the roof and floor moves and deforms within certain limits,which causes stress changing. Fracture fields are redistributed, ground stress is reduced, the coal seam expands, the coal se