孙村煤矿1.8Mta新井设计含5张CAD图.zip
孙村煤矿1.8Mta新井设计含5张CAD图.zip,煤矿,1.8,Mta,设计,CAD
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, gas emission 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, advanced discharge 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 to research 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 the fracture; 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 weight S 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 of S 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 hydraulic extrusion 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 validity checking borehole was effective influence radius as shown in Fig3.1(a). We can calculate the length 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 the axial 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 how many boreholes are needed in order to control outburst.Fig3.1 The 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.Fig3.2 The 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.Fig3.3 The 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 seam decreased, stress concentration belt moved forward, and stress relief belt turned out to be wider. Meanwhile, the gas permeability of coal seam increased greatly, 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 was reduced 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(a)所示。我们可以计算长度L,由几何关系计算出注入孔的有效半径,值约为0.9米。同时,由于钻屑值S的预测值在8 m时超出临界值两倍,而且不断发生,我们也可以计算出注水孔的轴向有效范围。正如我们所知,注入孔的长度为10米,每个注入孔的影响半径是5米。从图3.1(b),我们可以计算出注入孔的轴向的有效圈。根据几何关系,轴向有效半径为2.5 m。因此,注水钻孔的有效半径为0.9米,钻孔的轴向有效范围为2.5米。根据这一结论,我们可以知道需要多少个钻孔,用来防治煤与瓦斯突出。图3.1 钻孔的有效影响范围(a)径向有效范围 (b)轴向有效范围3.2应力变化前后的措施根据-610 m W2EB8工作面40个钻孔钻屑量的值,可以计算出平均每钻一米钻孔的钻屑量,如图3.2所示。钻屑量S值由三部分组成。第一部分,煤柱S1的重量,它的直径等于钻孔的直径。第二部分,钻屑量S2的值,它受地应力的影响。第三部分,钻屑量S3的价值,它受喷出的瓦斯释放的能量的影响。在煤层条件和钻孔直径相同的条件下,S1为一个定值,S2和S3分别反映了煤层地应力和瓦斯的能量。因此,工作面前方煤层地应力的分布规律与钻孔钻屑量的变化规律一致,与钻孔深度的变化相关。从图3.2,我们可以知道,煤层地应力分布规律与钻孔钻屑量随钻孔深度变化的规律:在开始钻孔深度约在1 m3 m时,钻屑量增加了一点。它表明,煤层应力得到了充分释放。当钻孔深度超过3 m时,钻屑量逐渐增加。它表明,煤层已经进入了转型时期的压力带。在6 m9 m的深度,煤层进入了应力集中降低区域,最大应力在钻孔深度为9 m时,相比采取注水这一措施前,出现最大压力的深度至少前移了2 m。因此,应力降低带变的更宽。所以安全掘进距离提高了5m。3.3不同措施之间瓦斯涌出的变化规律根据-610m W2EB8工作面回风巷中40个钻孔的瓦斯喷出量,当钻孔注水后瓦斯涌出量的比例从0.07 m/min0.42 m /min变化。图3.3是一个典型的钻孔注水前后喷出的瓦斯浓度变化规律曲线图。钻孔注水前,瓦斯缓慢释放。注水后,瓦斯涌出量迅速增加。因为在液压注水之前,煤层压力被集中,煤层的透气性差。在使用液压注水后,高压水压裂煤层,煤层的应力状态的改变,应力集中区向前发展的。因此,煤层压力被释放,封闭裂缝打开,煤层透气性变高。大量的吸附性气体很快被释放;气体排放量增加。因此,在采取措施后煤层瓦斯含量降低,煤层压力也减少。图3.3 注水后瓦斯密度的变化4 液压挤压突出预防机制当液压注射高压水到事先已完成的钻孔时,水在煤层中的渗入速度快于煤炭渗流;此时,煤层断裂,向工作面移动。由于煤层的位移,应力集中带移至煤层更深处,临界状态带位置向深处移动;工作面附近的应力充分的释放。然后,煤层裂缝增加,煤层透气性大大增加。因此,气体由吸附状态转向游离状态,煤层瓦斯释放充分。瓦斯含量和瓦斯压力降低。同时,高压力不仅破坏了煤层,使压力释放,也湿润了煤层。煤层脆性降低,但煤层的塑性增强,防治煤与瓦斯突出能力得到增强。因此,水力挤出措施减少了瓦斯和周围煤层的压力。它也提高了煤与瓦斯突出性的压力,对煤与瓦斯突出作了全面的防治。5 结论1)与浅层松动爆破相比,先进的排放钻孔等,液压挤压操作技术简便,安全。它是一种方便和有效的防突措施。 2)在利用水力挤出措施后,煤层应力梯度下降,应力集中带前移,压力减缓带变的更宽。同时,煤层透气性大大增加,煤层储存的压力被充分释放,瓦斯含量和压力降低。它消除了造成煤与瓦斯突出的主要因素。 3)通过液压挤出措施,符合标准的钻孔有效性检查率明显提高,巷道掘进速度提高了1.5倍,具有良好的社会效益和经济效益。参考文献1 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
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