煤与瓦斯突出控制技术在高瓦斯煤层快速掘进中的应用外文文献翻译

英文原文Outburst control technology for rapid excavation in severe outburst coalQU Yang（ Department of Mining Engineering, Henan Engineering Technical School, Jiaozuo 454000, China ）Abstract: The advantages and disadvantages of various outburst prevention measures in heading face were analyzed. The mechanism of outburst prevention about hydraulic extrusion measure was studied, the technological parameters were introduced, and the effect of outburst prevention was investigated. The in-situ experimental results show that the hydraulic extrusion measures are applied in serious outburst mine, not only the stress of stimulate outburst is eliminated effectively but also the gas in coal seam is released efficiently, the measures get obvious effect on coal and gas outburst prevention, and the roadway driving speed is increased by 1.5 times, implementing a safe and rapid excavation.Keywords: mechanism of outburst prevention, outburst prevention measure, rapid excavation, hydraulic extrusion, water injectionIntroductionCoal and gas outburst is one of the most serious natural disasters in coal mine exploitation and is a complex dynamic phenomenon. According to the statistics of working place where coal and gas outburst occurred （Yu, 1992）, a great number of outburst accidents occurred at the heading face of coal roadway, taking up 66.2% of all outburst accidents, and the average outburst intensity was 66.9 t. When driving in coal roadway with severe outburst potential danger, gasemission is great, the situation shall become serious as gas concentration exceeds the standard, and the driving speed is affected so greatly in coal roadway that the average driving speed is only 35 m each month in countrywide outburst mines. The speed of driving is so slow that it affects the normal replacement between coal-driving and cutting. This situation consequently makes the time needed for gas drainage turn out to be short. A vicious circle starts when the gas drainage rate is practically low, which brings new potential danger to mines.In order to prevent coal and gas outburst efficiently in coal roadway,some outburst prevention measures are adopted, such as the measure of shallow loose explosion, advanceddischarge orifice, deep borehole control blasting, hydraulic flushing, etc. （Bo, 2000; Liu and Shi,2002; He, 2004; Liu et al., 2005）. A definite effect of outburst prevention has been achieved; nevertheless, they have respective disadvantages of safety and the slow driving speed. For example, shallow loose explosion is applied in coal seam whose anthrax is hard and outburst intensity is weak; it may induce outburst in severe outburst coal. The measuring time of advanced discharge orifice is long, and effective function region of its borehole is small, its repetition rate is high, and it may also induce coal and gas outburst in severe outburst coal. Deep borehole control blasting, because the technology of explosives filling is not essentially settled, and the technology of operation is complex and not available. Hydraulic flushing is mainly used to excavate rock crosscut or driving in coal seams whose flowing ability is strong. So, we need toresearch for new measures of outburst prevention to improve the driving speed under the safe circumstance.Hydraulic extrusion is a safe measure compared with other measures, its technology is easy,and the effect of outburst prevention is obvious. This technology was applied at Liyi Coal Mine in Huainan Mining Industrial （Group） Co., Ltd. The driving speed reached 100 m each month and got good economic benefits.1 Basic situationThe test roadway is a return airway of -610 m W2EB8 working face. It is at the east of the second mine section. The height mark of tunnel is -612 m; its designed length is 450 m. The roadway is supported by anchor net and anchor wire; its basal area is 11.2 m2. The thickness of B8 coal seam at this area is 3.0 m to 4.0 m, the coal seam strike is 140 to 160, and the rake angle is 20 to 25. The immediate roof of coal seam is grayish white sand rock, and its thickness is 4.0 m to 6.0 m. The lamination of rock stratum develops well. The floor of coal seam is compact shale and gray, and its thickness is 4.0 m to 6.0 m. This working face is at the bottom of F13-8-2 fracture, be-cause it is affected by this fracture. small derivative constitution develops, and the coal strike and inclination change greatly near thefracture; the thickness of coal seam changes. Because of small constitution and high gas content, the region has serious outburst potential. Since the roadway was exploited, advanced discharge orifice and joint excavation and gas drainage had been used, although, getting some effectiveness, validity checking and gas concentration often exceed the standard. The speed of driving is slow, and the average speed is less than 40 m each month; it affects the normal replacement between coal-driving and cutting. Therefore, we need a measure that can prevent outburst quickly.2 Outburst prevention measure of hydraulic extrusion2.1 Borehole arrangement parameterThere are 5 boreholes arranged at the heading face of coal roadway. These boreholes are at the soft coal seam and arranged at the shape of quincunx. Their diameter is 42 mm, the depth of holes is 9.5 m to 10 m, and the depth of plug is 3 m. The rake angle of boreholes is identical with the roadway grade.2.2 Water injection parameterThe actual injection pressure is 8 to 12 MPa at -610 m W2EB8 working face. When water injection at the area where anthrax is hard, injection pressure will be higher, and the maximum pressure is 15 MPa. Therefore, injection pressure is influenced by stress surrounding the strata and stability coefficient of coal. We adopt a new water injection mode that is injecting water into borehole one by one and increasing the pressure of injection gradually. When pressure displayed on manometer is reduced by 30% compared with the maximum pressure, it illustrates that this borehole has been finished; then, it is time to turn to another borehole. According to many tests, the total flowing rate of injection to 5 boreholes is about 4 m3, the average flowing rate of water injection is 0.8 m3 each borehole, and the total time of water injection is less than 2 h.3 Effect analyses of hydraulic extrusion3.1 Effective influence circleWhen driving in the return airway of-610 m W2EB8 working face, the value of drilling cuttings weightS was beyond the critical value seriously; it happened continuously twice before water injection. The first time was prediction borehole. It happened at the depth of 8 m on 23rd March 2006. The value of drilling cuttings weight S was equal to 28 kg. When drilled beyond the depth of 8 m, the dynamic phenomenon of jet orifice occurred. The second time was also prediction borehole that happened at the depth of 8 m on 24th March 2006. The value ofS was equal to 23 kg, and dynamic phenomenon also occurred beyond the depth of 8 m. However, after using the measure of hydraulic extrusion, the value of S was less than the critical value and was reduced to 2.9 and 2.2 kg, respectively. According to the measured methods of effective radius on the book of outburst prevention rules, the effective influence circle of hydraulicextrusion can be calculated by analyzing these typical cases（Coal Industrial Department, 1995）.The prediction borehole was used to be water injection holes. First, drilling the prediction borehole to the depth of 10 m and then, using the measure of hydraulic extrusion, injecting water into the borehole. Second, when water injection was finished, drilling a validity checking borehole at the open pore of the prediction borehole. It had an included angle of 5, it was at the depth of 10 m, and it was used to check the result of hydraulic extrusion measure. Third, measuring the value of drilling cuttings weight at every meter. These values were compared with values of prediction borehole at the same depth. When the value of validity checking was less than the critical value, then the maximum distance between the prediction borehole and validitychecking borehole was effective influence radius as shown in Fig3.1（a）. We can calculate thelength of L, the effective radius of injection hole, by geometrical relationship as equal to 0.9 m. Meanwhile, because the prediction value of S was beyond the critical value at the depth of 8 m twice, and it happened continuously, we can also calculate the axial influence circle of the injection hole. As we know, the length of injection holes was 10 m. Every circle can drive 5 m,and 5 m was left as advanced distance. From Fig3.1（b）, we can calculate the length of Las theaxial influence circle of the injection hole. According to the geometrical relationship, the value of Lwas 2.5 m. Therefore, the effective radius of water injection borehole was 0.9 m, and the axial influence circle of the borehole was 2.5 m. According to this conclusion, we can know howmany boreholes are needed in order to control outburst.Fig3.1The effective influence circle of borehole（a） Radial range of influence（b） Axial range of influence3.2 Variations of stress before and after the measureAccording to the statistics of the value of drilling cuttings weight of 40 water injection circles in the return airway of -610 m W2EB8 working face, the average value of drilling cuttings weight of every meter was calculated and drew as in Fig.2. The value of drilling cuttings weight S is composed of three parts. First, the weight of coal wedge S1; its diameter was equal to the boreholes diameter. Second, the value of drilling cuttings weight S2; it was induced by the element of ground stress. Third, the value of drilling cuttings weight S3; it was induced by energy release of gas. Under the same condition of coal seam and the definite borehole diameter,S1 was a definite value and S2 and S3 reflected the ground stress of coal seam and potential energy of gas, respectively. Therefore, the stress distribution state of coal seam in the front of working face corresponded with the variation rule of the value of drilling cuttings weight following the depth change of borehole. From Fig.2, we can know the stress distribution rule of coal seam following the variation of the value of drilling cuttings weight along the depth of borehole: at the beginning of the borehole, about the depth of 1 to 3 m, the value of drilling cuttings weight increased a bit; it indicated that coal stress was released adequately. The value of drilling cuttings weight increased gradually when the depth was more than 3 m; it indicated that coal seam had entered the stress belt of transition. At the depth of 6 to 9 m, the coal seam entered the stress concentration decreased obviously, and the maximum stress site was at the depth of 9 m; it moved forward for 2 m at least compared with the maximum stress site before water injection. Therefore, the pressure relief belt turned out to be wider. We can drive safely when there is 5 m left as advanced distance.Fig3.2The variation values of drilling cutting weight following the depth of borehole3.3 Variation rule of gas emission among the measureAccording to the statistics of gas emission of 40 water injection circles in the return airway of -610 m W2EB8 working face, the amount of gas emission increased from 0.07 to 0.42 m/min after injecting water into the coal seam. Fig3.3 is a typical gas concentration changing curve before and after injecting water. Before injecting water, gas was released slowly. During water injection, gas emission increased quickly and changed continuously following the destruction of coal seam. After water injection, gas emission was also high. Because coal seam stress was concentrated before using the measure of hydraulic extrusion, the gas permeability of coal seam was bad. There was plenty of gas stored in the coal seam. After using the measure of hydraulic extrusion, the high-pressure water fractured the coal seam, the stress state of coal seam changed, and the stress concentration region moved forward. Therefore, the stress of coal seam was released, the closed crack seam was opened, and the gas permeability of coal seam turned out to be high. A great deal of adsorbed gas was released quickly; gas emission increased. Therefore, the gas content of coal seam was reduced after the measure, and the pressure of coal seam was also reduced.Fig3.3The change of gas density for and after the water injection4 Outburst prevention mechanism of hydraulic extrusionWhen injecting high-pressure water into boreholes that are finished beforehand, the velocity of water is faster than coal seepage; then, the coal seam is fractured and moves towards the working face. Because of the displacement of coal, the stress concentration belt is moved to the deeper site of coal seam, and the depth of critical state belt turned out to be longer; the stress surrounding the near working face is released sufficiently. Then, the crack of coal seam increases, and the gas permeability of coal seam increases greatly. As a result, gas desorption is promoted and gas stored in coal seam is released sufficiently. Gas content and gas pressure are reduced.Meanwhile, the high pressure not only destructs the coal seam, making stress released, but also increases and humidifies the coal seam. The coal brittleness is diminished, the plasticity of coal is enhanced, and the ability of preventing coal and gas outburst is enhanced. Therefore, the measure of hydraulic extrusion reduces the gas pressure and stress surrounding the coal seam. It also enhances the resistance pressure of coal and gas outburst and makes a comprehensive measure of outburst prevention.5 Conclusions（1）Compared with measures of shallow loose explosion, advanced discharge orifice, etc., the operation technology of hydraulic extrusion is easy and safe. It is a convenient and effective measure of outburst prevention.（2） After using the measure of hydraulic extrusion, the stress gradient of coal seamdecreased, stress concentration belt moved forward, and stress relief belt turned out to be wider. Meanwhile, the gas permeability of coal seam increasedgreatly, gas stored in coal was released adequately, and gas content and pressure were reduced. It eliminated major power that would agitate coal and gas outburst.（3） By the measure of hydraulic extrusion, the super standard rate of validity check wasreduced obviously, and the roadway driving speed was increased by 1.5 times with good social and economic benefits.References1 Bo F S, 2000. The technology of gas prevention for excavation in roadway.Mining Safety Environmental Protection, 27（4）: 42-44.2 Coal Industrial Department, 1995. The rule of coal and gas outburst prevention. Beijing: China Coal Industry Publishing House.3 He Y S, 2004. Exploration of loose explosion and its outburst prevention function principles.Coal Technology, 23（7）: 105-106.4 Liu J, Shi B M, 2002. Application of deep borehole blasting in coal seam with high outburst and lower permeability. Coal Science Technology Magazine, （3）: 1-3.5 Liu M J, Kong L A, Hao F C, Xin X P, W G Y, Liu Y W, 2005. Application of hydraulic flushing technology in severe outburst coal.Journal of China Coal Society, 30（4）: 451-454.6 Yu Q X, 1992. Gas prevention and cure of mines. Xuzhou: China University of Mining and Technology Press.中文译文煤与瓦斯突出控制技术在高瓦斯煤层快速掘进中的应用曲阳（采矿工程，河南工程技术学院，焦作 454000，中国） 摘要：分析现有掘进面瓦斯防治措施的优缺点。通过对瓦斯防治有关的机理的研究,提出了 水力挤出防治瓦斯的方法，并对技术参数进行了详细介绍，同时对影响瓦斯防治进行了实 验研究。现场实验结果表明，水力挤出措施应用于煤与瓦斯突出矿井，不仅有效的减弱了 瓦斯的突出应力并且控制了瓦斯在煤层中的释放，这些措施在控制煤与瓦斯突出上得到了 显著的效果。对存在煤与瓦斯突出危险的巷道，掘进速度提高了 1.5 倍，实现了安全、快 速掘进。关键字：煤与瓦斯突出；预防措施；快速掘进、液压注水前言煤与瓦斯突出是煤矿自然灾害危害最大的一种，同时其发生作用的机理也相对复杂。 据统计（发生煤与瓦斯突出的工作面，1992 年），大量的煤与瓦斯突出事故发生在煤巷掘 进工作面，占煤与瓦斯突出事故总数的 66.2%，平均突出瓦斯量为 66.9 t。当在突出危险严 重的煤巷中掘进时，瓦斯涌出量很大，瓦斯浓度超过安全界限，煤巷的掘进速度大为降低， 平均月进尺只有 35m。掘进速度过慢影响了正常的采掘接替。而这种情况又使瓦斯抽放所 需的时间变成很短。这样就形成了瓦斯抽放的恶性循环，给矿井生产带来了潜在的新危险。为了防治存在煤与瓦斯突出危险的煤巷，采取了一些有效的防突措施，如采用浅孔松 动爆破、先进的排放钻孔控制爆破，深孔水力冲刷等。并且在一定程度上取得了成功，然 而，这些技术都有各自的不足之处，尤其是都无法提高煤巷的掘进速度。例如，浅孔松动 爆破应用于煤层难以解决煤与瓦斯突出强度问题，它可能引起严重的煤与瓦斯突出。采用 先进的排放钻孔，打钻时间长，有效钻孔面积小，钻孔的重复率很高，而且还可能引发严 重的煤与瓦斯突出。深孔控制爆破技术，因为灌装炸药技术没有本质的解决，以及操作技 术复杂，所以不能大范围的应用在生产实践中。高压注水主要用于较松软的岩巷和煤巷掘 进。因此，我们需要研究新的防突措施，来提高安全的掘进速度。液压挤压是一种安全的施工措施，其施工工艺简单、防治突出效果显著。此技术已经 成功的应用在了淮南矿业集团的李一矿。其煤巷掘进速度达到了每月 100 米，取得了良好 的经济效益。1 矿区概况试验巷道位于东二采区-610 m 的 W2EB8 工作面。巷道设计标高为-612m，设计巷道 长度为 450m。整条巷道采用锚索和锚网联合支护，巷道断面为 11.2m。B8 煤层的厚度在 这一地区是 3.0 m 到 4.0 m，煤层走向倾角为 140160，倾向角度为 2025。煤 层的直接顶为分层的粉砂岩，其厚度为 4.0 m 到 6.0 m，岩层结构发育良好。底板岩层为紧 凑的灰页岩，厚度为 4.0 m-6.0 m。工作面位于 F13-8-2 断层的底部。由于受到断层的影响， 岩层中裂隙发育较多，煤炭走向、倾向倾角和煤层厚度在断层附近发生了变化。由于岩层 构造发生了改变和高瓦斯含量，该地区已存在严重的突出危险。尽管巷道采用了先进的瓦斯抽排孔抽排瓦斯，虽然得到一些成效，但瓦斯浓度仍然经常超标。煤巷的掘进速度低于 平均每月 40 m，极大的影响了正常的采掘接替。因此，需要找到一个新的措施来防止煤与 瓦斯突出，提高煤巷掘进速度。2 液压水力挤出防止煤与瓦斯突出2.1 钻孔布置参数在煤巷掘进工作面共布置 5 个钻孔。钻孔打在软煤层中并成梅花形排列，钻孔直径为42 mm，孔深为 9.5 m 至 10 m，而深度为 3 米插头。前角的钻孔与巷道级相同。2.2 钻孔注水参数-610 米 W2EB8 工作面的实际的注水压力在 812 MPa 之间。在注水困难区域，注射 压力将会提高，最大压力为 15 MPa。因此，注射压力是受周围岩层的硬度和煤层的普氏系 数的影响。为此我们采用一种新的注水模式，即对钻孔依次注水，逐步提高注射压力。当 压力表显示的压力相比最大压力减少 30时，这说明此钻孔的注水已完成。然后，再转向 另一个钻孔。根据许多试验数据表明，5 个钻孔的总注入量约为 4 m，平均每个钻孔的注 水量为 0.8 m，注水总时间小于 2 小时。3 水力挤出效应分析3.1 有效的影响圈在使用水力挤出措施前，当在-610 米的 W2EB8 掘进工作面回风巷打钻时，钻屑量 S 值连续两次严重超出了临界值。第一次是预测钻孔。事情发生 2006 年 3 月 23 日，当钻孔 打到 8 m 的深度时。钻屑量的 S 值等于 28 公斤。当超出了 8 米钻孔深度，发生了喷孔的 动态现象。第二次也是预测钻孔，发生于 2006 年 3 月 24 日，当钻孔打到 8 米的深度时。 钻屑量 S 值等于 23 公斤，当超出了 8 米钻孔深度，同样发生了喷孔的动态现象。但是， 在使用了水力挤出措施之后，钻屑值 S 减少到了 2.9 kg 和 2.2 kg。根据对防突有效半径的 测量方法，液压挤压的有效影响范围可以通过分析这些（煤炭工业部，1995 年）的典型案 件来计算。该预测是用于注水的钻孔。首先，预测钻孔钻至 10 米的深度，然后，利用水 力挤出措施，向钻孔中注水。第二，当注水完成后，钻一个有效性检查钻孔联通预测钻孔。 它与预测钻孔的夹角为 5 ，钻孔深度为 10 m，它被用来检查水力挤出措施的效果。第三， 测量每米的钻屑重量。将位于同一钻孔深度的钻屑值进行比较。当有效性检查值小于临界 值，然后有效性检查钻孔和预测钻孔之间的最大距离就是有效影响半径，如图 3.1（