姚橋煤礦5.0 Mta新井設(shè)計(jì)含5張CAD圖-采礦工程.zip

姚橋煤礦5.0 Mta新井設(shè)計(jì)含5張CAD圖-采礦工程.zip,姚橋煤礦5.0,Mta新井設(shè)計(jì)含5張CAD圖-采礦工程,煤礦,5.0,Mta,設(shè)計(jì),CAD,采礦工程 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.中文譯文煤與瓦斯突出控制技術(shù)在高瓦斯煤層快速掘進(jìn)中的應(yīng)用曲陽(yáng)（采礦工程，河南工程技術(shù)學(xué)院，焦作454000，中國(guó)）摘要：分析現(xiàn)有掘進(jìn)面瓦斯防治措施的優(yōu)缺點(diǎn)。通過(guò)對(duì)瓦斯防治有關(guān)的機(jī)理的研究,提出了水力擠出防治瓦斯的方法，并對(duì)技術(shù)參數(shù)進(jìn)行了詳細(xì)介紹，同時(shí)對(duì)影響瓦斯防治進(jìn)行了實(shí)驗(yàn)研究?，F(xiàn)場(chǎng)實(shí)驗(yàn)結(jié)果表明，水力擠出措施應(yīng)用于煤與瓦斯突出礦井，不僅有效的減弱了瓦斯的突出應(yīng)力并且控制了瓦斯在煤層中的釋放，這些措施在控制煤與瓦斯突出上得到了顯著的效果。對(duì)存在煤與瓦斯突出危險(xiǎn)的巷道，掘進(jìn)速度提高了1.5倍，實(shí)現(xiàn)了安全、快速掘進(jìn)。關(guān)鍵字：煤與瓦斯突出；預(yù)防措施；快速掘進(jìn)、液壓注水前言 煤與瓦斯突出是煤礦自然災(zāi)害危害最大的一種，同時(shí)其發(fā)生作用的機(jī)理也相對(duì)復(fù)雜。據(jù)統(tǒng)計(jì)（發(fā)生煤與瓦斯突出的工作面，1992年），大量的煤與瓦斯突出事故發(fā)生在煤巷掘進(jìn)工作面，占煤與瓦斯突出事故總數(shù)的66.2%，平均突出瓦斯量為66.9 t。當(dāng)在突出危險(xiǎn)嚴(yán)重的煤巷中掘進(jìn)時(shí)，瓦斯涌出量很大，瓦斯?jié)舛瘸^(guò)安全界限，煤巷的掘進(jìn)速度大為降低，平均月進(jìn)尺只有35m。掘進(jìn)速度過(guò)慢影響了正常的采掘接替。而這種情況又使瓦斯抽放所需的時(shí)間變成很短。這樣就形成了瓦斯抽放的惡性循環(huán)，給礦井生產(chǎn)帶來(lái)了潛在的新危險(xiǎn)。為了防治存在煤與瓦斯突出危險(xiǎn)的煤巷，采取了一些有效的防突措施，如采用淺孔松動(dòng)爆破、先進(jìn)的排放鉆孔控制爆破，深孔水力沖刷等。并且在一定程度上取得了成功，然而，這些技術(shù)都有各自的不足之處，尤其是都無(wú)法提高煤巷的掘進(jìn)速度。例如，淺孔松動(dòng)爆破應(yīng)用于煤層難以解決煤與瓦斯突出強(qiáng)度問(wèn)題，它可能引起嚴(yán)重的煤與瓦斯突出。采用先進(jìn)的排放鉆孔，打鉆時(shí)間長(zhǎng)，有效鉆孔面積小，鉆孔的重復(fù)率很高，而且還可能引發(fā)嚴(yán)重的煤與瓦斯突出。深孔控制爆破技術(shù)，因?yàn)楣嘌b炸藥技術(shù)沒(méi)有本質(zhì)的解決，以及操作技術(shù)復(fù)雜，所以不能大范圍的應(yīng)用在生產(chǎn)實(shí)踐中。高壓注水主要用于較松軟的巖巷和煤巷掘進(jìn)。因此，我們需要研究新的防突措施，來(lái)提高安全的掘進(jìn)速度。液壓擠壓是一種安全的施工措施，其施工工藝簡(jiǎn)單、防治突出效果顯著。此技術(shù)已經(jīng)成功的應(yīng)用在了淮南礦業(yè)集團(tuán)的李一礦。其煤巷掘進(jìn)速度達(dá)到了每月100米，取得了良好的經(jīng)濟(jì)效益。1 礦區(qū)概況試驗(yàn)巷道位于東二采區(qū)-610 m的 W2EB8工作面。巷道設(shè)計(jì)標(biāo)高為-612m，設(shè)計(jì)巷道長(zhǎng)度為450m。整條巷道采用錨索和錨網(wǎng)聯(lián)合支護(hù)，巷道斷面為11.2m。B8煤層的厚度在這一地區(qū)是3.0 m到4.0 m，煤層走向傾角為140160，傾向角度為2025。煤層的直接頂為分層的粉砂巖，其厚度為4.0 m到6.0 m，巖層結(jié)構(gòu)發(fā)育良好。底板巖層為緊湊的灰頁(yè)巖，厚度為4.0 m-6.0 m。工作面位于F13-8-2斷層的底部。由于受到斷層的影響，巖層中裂隙發(fā)育較多，煤炭走向、傾向傾角和煤層厚度在斷層附近發(fā)生了變化。由于巖層構(gòu)造發(fā)生了改變和高瓦斯含量，該地區(qū)已存在嚴(yán)重的突出危險(xiǎn)。盡管巷道采用了先進(jìn)的瓦斯抽排孔抽排瓦斯，雖然得到一些成效，但瓦斯?jié)舛热匀唤?jīng)常超標(biāo)。煤巷的掘進(jìn)速度低于平均每月40 m，極大的影響了正常的采掘接替。因此，需要找到一個(gè)新的措施來(lái)防止煤與瓦斯突出，提高煤巷掘進(jìn)速度。2 液壓水力擠出防止煤與瓦斯突出2.1 鉆孔布置參數(shù)在煤巷掘進(jìn)工作面共布置5個(gè)鉆孔。鉆孔打在軟煤層中并成梅花形排列，鉆孔直徑為42 mm，孔深為9.5 m至10 m，而深度為3米插頭。前角的鉆孔與巷道級(jí)相同。2.2 鉆孔注水參數(shù)-610米W2EB8工作面的實(shí)際的注水壓力在812 MPa之間。在注水困難區(qū)域，注射壓力將會(huì)提高，最大壓力為15 MPa。因此，注射壓力是受周圍巖層的硬度和煤層的普氏系數(shù)的影響。為此我們采用一種新的注水模式，即對(duì)鉆孔依次注水，逐步提高注射壓力。當(dāng)壓力表顯示的壓力相比最大壓力減少30時(shí)，這說(shuō)明此鉆孔的注水已完成。然后，再轉(zhuǎn)向另一個(gè)鉆孔。根據(jù)許多試驗(yàn)數(shù)據(jù)表明，5個(gè)鉆孔的總注入量約為4 m，平均每個(gè)鉆孔的注水量為0.8 m，注水總時(shí)間小于2小時(shí)。3 水力擠出效應(yīng)分析3.1有效的影響圈在使用水力擠出措施前，當(dāng)在-610米的W2EB8掘進(jìn)工作面回風(fēng)巷打鉆時(shí)，鉆屑量S值連續(xù)兩次嚴(yán)重超出了臨界值。第一次是預(yù)測(cè)鉆孔。事情發(fā)生2006年3月23日，當(dāng)鉆孔打到8 m的深度時(shí)。鉆屑量的S值等于28公斤。當(dāng)超出了8米鉆孔深度，發(fā)生了噴孔的動(dòng)態(tài)現(xiàn)象。第二次也是預(yù)測(cè)鉆孔，發(fā)生于2006年3月24日，當(dāng)鉆孔打到8米的深度時(shí)。鉆屑量S值等于23公斤，當(dāng)超出了8米鉆孔深度，同樣發(fā)生了噴孔的動(dòng)態(tài)現(xiàn)象。但是，在使用了水力擠出措施之后，鉆屑值S減少到了2.9 kg和2.2 kg。根據(jù)對(duì)防突有效半徑的測(cè)量方法，液壓擠壓的有效影響范圍可以通過(guò)分析這些（煤炭工業(yè)部，1995年）的典型案件來(lái)計(jì)算。該預(yù)測(cè)是用于注水的鉆孔。首先，預(yù)測(cè)鉆孔鉆至10米的深度，然后，利用水力擠出措施，向鉆孔中注水。第二，當(dāng)注水完成后，鉆一個(gè)有效性檢查鉆孔聯(lián)通預(yù)測(cè)鉆孔。它與預(yù)測(cè)鉆孔的夾角為5 ，鉆孔深度為10 m，它被用來(lái)檢查水力擠出措施的效果。第三，測(cè)量每米的鉆屑重量。將位于同一鉆孔深度的鉆屑值進(jìn)行比較。當(dāng)有效性檢查值小于臨界值，然后有效性檢查鉆孔和預(yù)測(cè)鉆孔之間的最大距離就是有效影響半徑，如圖3.1（a）所示。我們可以計(jì)算長(zhǎng)度L，由幾何關(guān)系計(jì)算出注入孔的有效半徑，值約為0.9米。同時(shí)，由于鉆屑值S的預(yù)測(cè)值在8 m時(shí)超出臨界值兩倍，而且不斷發(fā)生，我們也可以計(jì)算出注水孔的軸向有效范圍。正如我們所知，注入孔的長(zhǎng)度為10米，每個(gè)注入孔的影響半徑是5米。從圖3.1（b），我們可以計(jì)算出注入孔的軸向的有效圈。根據(jù)幾何關(guān)系，軸向有效半徑為2.5 m。因此，注水鉆孔的有效半徑為0.9米，鉆孔的軸向有效范圍為2.5米。根據(jù)這一結(jié)論，我們可以知道需要多少個(gè)鉆孔，用來(lái)防治煤與瓦斯突出。圖3.1 鉆孔的有效影響范圍（a）徑向有效范圍 （b）軸向有效范圍3.2應(yīng)力變化前后的措施根據(jù)-610 m W2EB8工作面40個(gè)鉆孔鉆屑量的值，可以計(jì)算出平均每鉆一米鉆孔的鉆屑量，如圖3.2所示。鉆屑量S值由三部分組成。第一部分，煤柱S1的重量，它的直徑等于鉆孔的直徑。第二部分，鉆屑量S2的值，它受地應(yīng)力的影響。第三部分，鉆屑量S3的價(jià)值，它受噴出的瓦斯釋放的能量的影響。在煤層條件和鉆孔直徑相同的條件下，S1為一個(gè)定值，S2和S3分別反映了煤層地應(yīng)力和瓦斯的能量。因此，工作面前方煤層地應(yīng)力的分布規(guī)律與鉆孔鉆屑量的變化規(guī)律一致，與鉆孔深度的變化相關(guān)。從圖3.2，我們可以知道，煤層地應(yīng)力分布規(guī)律與鉆孔鉆屑量隨鉆孔深度變化的規(guī)律：在開(kāi)始鉆孔深度約在1 m3 m時(shí)，鉆屑量增加了一點(diǎn)。它表明，煤層應(yīng)力得到了充分釋放。當(dāng)鉆孔深度超過(guò)3 m時(shí)，鉆屑量逐漸增加。它表明，煤層已經(jīng)進(jìn)入了轉(zhuǎn)型時(shí)期的壓力帶。在6 m9 m的深度，煤層進(jìn)入了應(yīng)力集中降低區(qū)域，最大應(yīng)力在鉆孔深度為9 m時(shí)，相比采取注水這一措施前，出現(xiàn)最大壓力的深度至少前移了2 m。因此，應(yīng)力降低帶變的更寬。所以安全掘進(jìn)距離提高了5m。3.3不同措施之間瓦斯涌出的變化規(guī)律根據(jù)-610m W2EB8工作面回風(fēng)巷中40個(gè)鉆孔的瓦斯噴出量，當(dāng)鉆孔注水后瓦斯涌出量的比例從0.07 m/min0.42 m /min變化。圖3.3是一個(gè)典型的鉆孔注水前后噴出的瓦斯?jié)舛茸兓?guī)律曲線圖。鉆孔注水前，瓦斯緩慢釋放。注水后，瓦斯涌出量迅速增加。因?yàn)樵谝簤鹤⑺埃簩訅毫Ρ患?，煤層的透氣性差。在使用液壓注水后，高壓水壓裂煤層，煤層的?yīng)力狀態(tài)的改變，應(yīng)力集中區(qū)向前發(fā)展的。因此，煤層壓力被釋放，封閉裂縫打開(kāi)，煤層透氣性變高。大量的吸附性氣體很快被釋放；氣體排放量增加。因此，在采取措施后煤層瓦斯含量降低，煤層壓力也減少。圖3.3 注水后瓦斯密度的變化4 液壓擠壓突出預(yù)防機(jī)制當(dāng)液壓注射高壓水到事先已完成的鉆孔時(shí)，水在煤層中的滲入速度快于煤炭滲流；此時(shí)，煤層斷裂，向工作面移動(dòng)。由于煤層的位移，應(yīng)力集中帶移至煤層更深處，臨界狀態(tài)帶位置向深處移動(dòng)；工作面附近的應(yīng)力充分的釋放。然后，煤層裂縫增加，煤層透氣性大大增加。因此，氣體由吸附狀態(tài)轉(zhuǎn)向游離狀態(tài)，煤層瓦斯釋放充分。瓦斯含量和瓦斯壓力降低。同時(shí)，高壓力不僅破壞了煤層，使壓力釋放，也濕潤(rùn)了煤層。煤層脆性降低，但煤層的塑性增強(qiáng)，防治煤與瓦斯突出能力得到增強(qiáng)。因此，水力擠出措施減少了瓦斯和周圍煤層的壓力。它也提高了煤與瓦斯突出性的壓力，對(duì)煤與瓦斯突出作了全面的防治。5 結(jié)論1）與淺層松動(dòng)爆破相比，先進(jìn)的排放鉆孔等，液壓擠壓操作技術(shù)簡(jiǎn)便，安全。它是一種方便和有效的防突措施。 2）在利用水力擠出措施后，煤層應(yīng)力梯度下降，應(yīng)力集中帶前移，壓力減緩帶變的更寬。同時(shí)，煤層透氣性大大增加，煤層儲(chǔ)存的壓力被充分釋放，瓦斯含量和壓力降低。它消除了造成煤與瓦斯突出的主要因素。 3）通過(guò)液壓擠出措施，符合標(biāo)準(zhǔn)的鉆孔有效性檢查率明顯提高，巷道掘進(jìn)速度提高了1.5倍，具有良好的社會(huì)效益和經(jīng)濟(jì)效益。參考文獻(xiàn)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 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