祁東煤礦0.9Mta新井設計-采礦工程含5張CAD圖.zip,祁東,煤礦,0.9,Mta,設計,采礦工程,CAD 英文原文 Outburst control technology for rapid excavation in severe outburst coal QU 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 injection Introduction Coal 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 situation The 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 140o to 160o, and the rake angle is 20o to 25o. 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 extrusion 2.1 Borehole arrangement parameter There 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 parameter The 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 extrusion 3.1 Effective influence circle When 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 L＇as the axial influence circle of the injection hole. According to the geometrical relationship, the value of L＇was 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 influence 3.2 Variations of stress before and after the measure According 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 borehole’s 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 borehole 3.3 Variation rule of gas emission among the measure According 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 m3/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 injection 4 Outburst prevention mechanism of hydraulic extrusion When 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. References [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. 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在高瓦斯煤層快速掘進中的應用 曲陽 （采礦工程，河南工程技術學院，焦作 454000，中國） 摘要：分析現(xiàn)有掘進面瓦斯防治措施的優(yōu)缺點。通過對瓦斯防治有關的機理的研究,提出了 水力擠出防治瓦斯的方法，并對技術參數(shù)進行了詳細介紹，同時對影響瓦斯防治進行了實 驗研究?，F(xiàn)場實驗結果表明，水力擠出措施應用于煤與瓦斯突出礦井，不僅有效的減弱了 瓦斯的突出應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。對存在煤與瓦斯突出危險的巷道，掘進速度提高了 1.5 倍，實現(xiàn)了安全、快 速掘進。 關鍵字：煤與瓦斯突出；預防措施；快速掘進、液壓注水 前言 煤與瓦斯突出是煤礦自然災害危害最大的一種，同時其發(fā)生作用的機理也相對復雜。 據(jù)統(tǒng)計（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。當在突出危險嚴 重的煤巷中掘進時，瓦斯涌出量很大，瓦斯?jié)舛瘸^安全界限，煤巷的掘進速度大為降低， 平均月進尺只有 35m。掘進速度過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)帶來了潛在的新危險。 為了防治存在煤與瓦斯突出危險的煤巷，采取了一些有效的防突措施，如采用淺孔松 動爆破、先進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，這些技術都有各自的不足之處，尤其是都無法提高煤巷的掘進速度。例如，淺孔松動 爆破應用于煤層難以解決煤與瓦斯突出強度問題，它可能引起嚴重的煤與瓦斯突出。采用 先進的排放鉆孔，打鉆時間長，有效鉆孔面積小，鉆孔的重復率很高，而且還可能引發(fā)嚴 重的煤與瓦斯突出。深孔控制爆破技術，因為灌裝炸藥技術沒有本質的解決，以及操作技 術復雜，所以不能大范圍的應用在生產(chǎn)實踐中。高壓注水主要用于較松軟的巖巷和煤巷掘 進。因此，我們需要研究新的防突措施，來提高安全的掘進速度。 液壓擠壓是一種安全的施工措施，其施工工藝簡單、防治突出效果顯著。此技術已經(jīng) 成功的應用在了淮南礦業(yè)集團的李一礦。其煤巷掘進速度達到了每月 100 米，取得了良好 的經(jīng)濟效益。 1 礦區(qū)概況 試驗巷道位于東二采區(qū)-610 m 的 W2EB8 工作面。巷道設計標高為-612m，設計巷道 長度為 450m。整條巷道采用錨索和錨網(wǎng)聯(lián)合支護，巷道斷面為 11.2m2。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 140゜～160゜，傾向角度為 20゜～25゜。煤 層的直接頂為分層的粉砂巖，其厚度為 4.0 m 到 6.0 m，巖層結構發(fā)育良好。底板巖層為緊 湊的灰頁巖，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 構造發(fā)生了改變和高瓦斯含量，該地區(qū)已存在嚴重的突出危險。盡管巷道采用了先進的瓦 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。煤巷的掘進速度低于 平均每月 40 m，極大的影響了正常的采掘接替。因此，需要找到一個新的措施來防止煤與 瓦斯突出，提高煤巷掘進速度。 2 液壓水力擠出防止煤與瓦斯突出 2.1 鉆孔布置參數(shù) 在煤巷掘進工作面共布置 5 個鉆孔。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相同。 2.2 鉆孔注水參數(shù) -610 米 W2EB8 工作面的實際的注水壓力在 8～12 MPa 之間。在注水困難區(qū)域，注射 壓力將會提高，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，即對鉆孔依次注水，逐步提高注射壓力。當 壓力表顯示的壓力相比最大壓力減少 30％時，這說明此鉆孔的注水已完成。然后，再轉向 另一個鉆孔。根據(jù)許多試驗數(shù)據(jù)表明，5 個鉆孔的總注入量約為 4 m3，平均每個鉆孔的注 水量為 0.8 m3，注水總時間小于 2 小時。 3 水力擠出效應分析 3.1 有效的影響圈 在使用水力擠出措施前，當在-610 米的 W2EB8 掘進工作面回風巷打鉆時，鉆屑量 S 值連續(xù)兩次嚴重超出了臨界值。第一次是預測鉆孔。事情發(fā)生 2006 年 3 月 23 日，當鉆孔 打到 8 m 的深度時。鉆屑量的 S 值等于 28 公斤。當超出了 8 米鉆孔深度，發(fā)生了噴孔的 動態(tài)現(xiàn)象。第二次也是預測鉆孔，發(fā)生于 2006 年 3 月 24 日，當鉆孔打到 8 米的深度時。 鉆屑量 S 值等于 23 公斤，當超出了 8 米鉆孔深度，同樣發(fā)生了噴孔的動態(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)對防突有效半徑的 測量方法，液壓擠壓的有效影響范圍可以通過分析這些（煤炭工業(yè)部，1995 年）的典型案 件來計算。該預測是用于注水的鉆孔。首先，預測鉆孔鉆至 10 米的深度，然后，利用水 力擠出措施，向鉆孔中注水。第二，當注水完成后，鉆一個有效性檢查鉆孔聯(lián)通預測鉆孔。 它與預測鉆孔的夾角為 5 °，鉆孔深度為 10 m，它被用來檢查水力擠出措施的效果。第三， 測量每米的鉆屑重量。將位于同一鉆孔深度的鉆屑值進行比較。當有效性檢查值小于臨界 值，然后有效性檢查鉆孔和預測鉆孔之間的最大距離就是有效影響半徑，如圖 3.1（a）所 示。我們可以計算長度 L，由幾何關系計算出注入孔的有效半徑，值約為 0.9 米。同時， 由于鉆屑值 S 的預測值在 8 m 時超出臨界值兩倍，而且不斷發(fā)生，我們也可以計算出注水 孔的軸向有效范圍。正如我們所知，注入孔的長度為 10 米，每個注入孔的影響半徑是 5 米。從圖 3.1（b），我們可以計算出注入孔的軸向的有效圈。根據(jù)幾何關系，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 一結論，我們可以知道需要多少個鉆孔，用來防治煤與瓦斯突出。 123 頁 中國礦業(yè)大學 2012 屆本科生畢業(yè)設計 第 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 應力變化前后的措施 根據(jù)-610 m W2EB8 工作面 40 個鉆孔鉆屑量的值，可以計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，它受地應力的影響。第三部分，鉆屑量 S3 的 價值，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 個定值，S2 和 S3 分別反映了煤層地應力和瓦斯的能量。因此，工作面前方煤層地應力的分 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。從圖 3.2，我們可以知道， 煤層地應力分布規(guī)律與鉆孔鉆屑量隨鉆孔深度變化的規(guī)律：在開始鉆孔深度約在 1 m～3 m 時，鉆屑量增加了一點。它表明，煤層應力得到了充分釋放。當鉆孔深度超過 3 m 時，鉆 屑量逐漸增加。它表明，煤層已經(jīng)進入了轉型時期的壓力帶。在 6 m～9 m 的深度，煤層 進入了應力集中降低區(qū)域，最大應力在鉆孔深度為 9 m 時，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，應力降低帶變的更寬。所以安全掘進距離提高 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 工作面回風巷中 40 個鉆孔的瓦斯噴出量，當鉆孔注水后瓦斯涌出 量的比例從 0.07 m3/min～0.42 m3 /min 變化。圖 3.3 是一個典型的鉆孔注水前后噴出的瓦斯 濃度變化規(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。因為 在液壓注水之前，煤層壓力被集中，煤層的透氣性差。在使用液壓注水后，高壓水壓裂煤 層，煤層的應力狀態(tài)的改變，應力集中區(qū)向前發(fā)展的。因此，煤層壓力被釋放，封閉裂縫 打開，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。 4 液壓擠壓突出預防機制 圖 3.3 注水后瓦斯密度的變化 當液壓注射高壓水到事先已完成的鉆孔時，水在煤層中的滲入速度快于煤炭滲流；此 時，煤層斷裂，向工作面移動。由于煤層的位移，應力集中帶移至煤層更深處，臨界狀態(tài) 帶位置向深處移動；工作面附近的應力充分的釋放。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，高壓力不僅破壞了煤層，使壓力釋放，也濕潤了煤層。煤層脆性降低，但煤 層的塑性增強，防治煤與瓦斯突出能力得到增強。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，對煤與瓦斯突出作了全面的防治。 5 結論 1）與淺層松動爆破相比，先進的排放鉆孔等，液壓擠壓操作技術簡便，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，煤層應力梯度下降，應力集中帶前移，壓力減緩帶變的 更寬。同時，煤層透氣性大大增加，煤層儲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）通過液壓擠出措施，符合標準的鉆孔有效性檢查率明顯提高，巷道掘進速度提高 了 1.5 倍，具有良好的社會效益和經(jīng)濟效益。 參考文獻 [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 preve