許廠煤礦3.0 Mta新井設(shè)計(jì)含5張CAD圖.zip

許廠煤礦3.0 Mta新井設(shè)計(jì)含5張CAD圖.zip,許廠煤礦3.0,Mta新井設(shè)計(jì)含5張CAD圖,煤礦,3.0,Mta,設(shè)計(jì),CAD Control of gas emissions in underground coal mines Klaus Noack*DMT-Gesellschaft fr Forschung und Prfung mbH, Institut fr Bewetterung, Klimatisierung und Staubbekmpfung, Franz-Fischer-Weg 61, Essen, GermanyReceived 2 August 1996; accepted 24 February 1997. Available online 24 November 1998. Abstract A high level of knowledge is now available in the extremely relevant field of underground gas emissions from coal mines. However, there are still tasks seeking improved solutions, such as prediction of gas emissions, choice of the most suitable panel design, extension of predrainage systems, further optimization of postdrainage systems, options for the control of gas emissions during retreat mining operations, and prevention of gas outbursts. Research results on these most important topics are presented and critically evaluated. Methods to predict gas emissions for disturbed and undisturbed longwall faces are presented. Prediction of the worked seam gas emission and the gas emission from headings are also mentioned but not examined in detail. The ventilation requirements are derived from the prediction results and in combination with gas drainage the best distribution of available air currents is planned. The drainage of the gas from the worked coal seam, also referred to as predrainage, can be performed without application of suction only by over or underworking the seam. But in cases where this simple method is not applicable or not effective enough, inseam-boreholes are needed to which suction is applied for a relatively long time. The reason for this is the low permeability of deep coal seams in Europe. The main influences on the efficiency of the different degasing methods are explained. Conventional gas drainage employing cross measure boreholes is still capable of improvement, in terms of drilling and equipment as well as the geometrical borehole parameters and the operation of the overall system. Improved control of gas emissions at the return end of retreating faces can be achieved by installation of gas drainage systems based on drainage roadways or with long and large diameter boreholes. The back-return method can be operated safely only with great difficulty, if at all. Another method is lean-gas drainage from the goaf. The gas outburst situation in Germany is characterized by events predominantly in the form of non-classical outbursts categorized as sudden liberation of significant quantities of gas. Recent research results in this field led to a classification of these phenomena into five categories, for which suitable early detection and prevention measures are mentioned.Author Keywords: gas emission; prediction; pre-degassing; gas drainage; gas outbursts1. Introduction Coal deposits contain mine gas (mostly methane) in quantities which are functions of the degree of coalification and permeability of the overburden rocks. This is the reason why the gas content of coal seams (and rock layers) varies from 0 m3/t in the flame coal and gas-flame coal of the northwestern Ruhr Basin to 25 m3/t in the anthracite of Ibbenbren in Germany.When influenced by mining activities this gas is emitted into the coal mine. For better understanding of this process a distinction has been established between basic and additional gas emissions. Basic gas emission is the gas influx from the worked coal seam, which is the equivalent of a partial influx in a multi-seam deposit and of the total gas influx in a single-seam deposit. Additional gas emission represents gas influx coming from neighbouring coal seams (in the case of a multi-seam deposit) and from associated rock layers. The additional gas emission may be in excess of ten times the basic gas emission. So it is mostly the additional gas emission which determines the measures to control the gas emission. In Germany the gas emission is considered to be under control if the gas concentration of the mine air can be kept permanently at all relevant places under 1% CH4. This value is at an adequate distance to the lower explosion limit of methane-air mixtures, which under normal conditions is 4.4% CH4. In exceptional cases, the permissible limit value can be raised to 1.5% CH4. For historical reasons, different permissible limits sometimes apply in other countries, for example 1.25% CH4 in the United Kingdom and up to 2% CH4 in France. Basically, the options for control of gas emission are as follows:(1) Total avoidance of gas release from the deposit. This is only possible with regard to the additional gas emission and only for mining procedures which do not affect stability; hence permeability of the overlying and underlying strata (e.g., room-and-pillar mining where the pillars are left standing during the development phase).(2) Removal of the gas from the deposit before working. For this purpose, all procedures for pre-degassing, either by vertical or by deflected cross measure boreholes drilled from the surface, or by inseam-holes drilled below ground, are technically suitable provided the natural or induced gas permeability permits pre-degassing.(3) Capture and drainage of the gas during mining operations before it mixes with the air flow. This is a classic procedure developed for capturing the additional gas using drainage boreholes, drainage roadways or drainage chambers.(4) Homogenize and evacuate the gas influx after diluting it with sufficient amount of air. This involves panel design, air supply, air distribution, and the prevention of gas outbursts. The following discussions concentrate on problems which are currently given priority in the European Union (EU) funded research. They also cover a significant portion of the gas emission problems worldwide. Problems from non-EU states (e.g., Australia, the Community of Independent States (CIS), South Africa and the United Stated of America (USA) are also taken into consideration, as far as the authors knowledge permits it. This subject matter is presented in a condensed form under the following headings: prediction of gas emissions; measures taken to control gas emissions; pre-degassing of coal seams; optimization of conventional gas drainage; control of gas emissions for retreating faces; and prevention of gas outbursts.2. Prediction of gas emissions Prediction of firedamp emission has been practized for many years in the German hardcoal industry (Winter, 1958; Schulz, 1959; Noack, 1970 and Noack, 1971; Flgge, 1971; Koppe, 1975) so that several prediction methods are now available. Among these, the following methods are mentioned:(1) the calculation of the amount of gas emission (Koppe, 1976; Noack, 1985), as used to deal with emission from both the worked coal seam and adjacent seams, which are disturbed by earlier mining activities;(2) the calculation of the reduction of gas pressure (Noack and Janas, 1984; Janas, 1985a and Janas, 1985b), as used in undisturbed parts of the deposit; and(3) prediction methods for the worked coal seam gas emission from longwall faces, for the gas emission from headings and for the gas emission from coal seams cut through during drifting. The first two methods provide a prediction of the specific gas emission from a mine working, expressed in cubic metres of gas per ton of saleable coal production. The gas influx to the mine working in cubic metres of gas per unit time, which is a relevant factor for mine planning, can be derived from multiplying the predicted result by the scheduled production volume. Both methods determine the mean gas emission from a coal face area for a nearly constant face advance rate during a sufficiently long period of time (several months). The prediction assumes that the zone from which the gas is emitted is fully developed, in other words the coal face starting phase has been passed. Furthermore, the coal face has to be above a critical length (i.e., longer than 180190 m at 600 m working depth and longer than 220240 m at 1000 m depth). The influx of gas to a coal face area (both into the mine air current and into the gas drainage system) is defined by the following factors: (1) the geometry and size of the zone from which gas is emitted, both in the roof and the floor of the face area, including the number and thickness of gas-bearing strata in that zone; (2) the gas content of the strata; (3) the degree of gas emission, as a function of time- and space-related influences; and (4) the intensity of mining activities. The geometry and size of the zone from which additional gas is emitted are simplified forming a parallelepiped above and below the worked area; its extension normal to the stratification depends on the prediction method. The number and location, type, and thickness of the strata in the zone from which additional gas is emitted can be derived from existing boreholes, staple-shafts, and roadways inclined to the stratification. The gas content of the strata (Paul, 1971; Janas, 1976; Janas and Opahle, 1986) is difficult to determine. There are two alternatives for direct gas content determination available for coal seams (Verlag Glckauf GmbH, 1987). One alternative uses samples of drillings from inseam-boreholes (for developed seams) and the other alternative uses core samples from boreholes inclined to the stratification (for undeveloped seams). Since a suitable method of determining the gas content of rock is not yet available, a double prediction is made with the first prediction neglecting the rock altogether and the second prediction using the assumption of an estimated gas content of the rock strata. The methods for predicting the proportion of gas content emitted are basically divergent. On the one hand the prediction, which is based on the degree of gas emission, assumes that the emitted gas proportion is not a function of the initial gas content but rather of the geometric location of the relevant strata towards the coal face area. The other method, which relies on gas pressure, commences with a fixed residual gas pressure, hence residual gas content. Its value depends on the geometric location of the strata. This means that the emitted proportion of the gas content, representing the balance against the initial gas content, depends on the latter.2.1. Prediction for previously disturbed conditionsThe method to predict the total gas make from longwalling in a previously disturbed zone in shallow to moderately inclined deposits (dip between 0 and 40 gon) is based on the degree of gas emission (Fig. 1). It uses the degree of gas emission curve designated as PFG for the roof (considering an attenuation factor of 0.016) and the curve designated as FGK for the floor.Fig. 1. PFG/FGK method. For practical reasons the upper boundary of the zone from which gas is emitted is assumed to be at h=+165 m, whereas, the lower boundary is at h=59 m. In the absence of empirical data a mean degree of gas emission of 75% in the worked coal seam is assumed. Above the seam, from the h=+0 m level to the h=+20 m level, and below the seam from the h=0 m level to the h=11 m level, the degree of gas emission is assumed to be 100%. For the purpose of prediction, the surrounding rock strata are considered as fictitious coal seams for which reduced gas contents are assumed. The reduction factors are 0.019 (for mudstone), 0.058 (for sandy shale) or 0.096 (for sandstone).2.2. Prediction for previously undisturbed conditions The method to predict the total gas make from longwalling in a previously undisturbed zone is based on the residual gas pressure profiles shown in Fig. 2. There are three zones visible in the roof and two in the floor, which are characterized by varying residual gas pressure gradients. The upper and lower boundaries of the zone from which gas is emitted (hlim and llim, respectively) are defined by the intersection of the residual gas pressure lines and the level of initial gas pressure pu, thus are dependent on the latter.Fig. 2. Gas pressure method: residual gas pressure lines dependent on thickness of the worked coal seam. The breaking points of the residual gas pressure profile for 1 m of worked coal seam thickness (continuous line) are defined by the coordinates in Table 1, whereas the lines are characterized by the residual gas pressure gradients also in Table 1.Table 1. Parameters for the gas pressure methodFull-size table (1K)View Within Article The dotted line on Fig. 2 applies to 1.5 m of worked coal seam thickness and shows that the h1 and h2 ordinate levels relating to the roof increase in linear proportion to the thickness of the worked coal seam, with gradients declining correspondingly. There is no dependence on coal seam thickness in the floor, where the value of l1 remains constant at 33 m. Based on the illustrated residual gas pressure profile, the residual gas pressures are first determined layer by layer in accordance with the mean normal distance of a layer from the worked coal seam and afterwards they are converted to residual gas contents using Langmuirs sorption isotherm. The difference between the initial and residual gas contents finally represents the emitted proportion of the adsorbed gas which is the required value. To this value will then be added the free gas, the proportion of which is found by multiplying the effective porosity of the strata under review by its thickness and gas pressure difference. Empirical values have to be used for the effective porosity of coal and rock for methane. Typical values for the coal are between 1 and 10%, and for the rock they are between 0.3 and 1.3%. The values vary in a wide range and depend on chronostratigraphy. In the absence of empirical values for the proportion of gas emission from the worked coal seam a value of 40% would be assumed.2.3. Comparison of the two methods The gas pressure method may claim the following advantages over the prediction based on the degree of gas emission: There are no rigid delimitations of the upper and lower zones from which gas is emitted. They rather depend on the value of the initial gas pressure and on the type of strata. In the roof the effect of the thickness of the worked coal seam is considered in the profile of residual gas pressure. The prediction takes into account not only the adsorbed gas but also the free gas; this is for both, the coal seams and the surrounding strata. The total gas content rather than the desorbable proportion is used for the prediction.2.4. Other methods The prediction methods for the worked coal seam gas emission in longwalls and for inseam-headings as well as for coal seam cut through operations during drifting with tunneling machines cannot be explained in detail. For further information refer to the following papers: Noack, 1977; Janas and Stamer, 1987; Noack and Janas, 1988; Noack and Opahle, 1992. It should be mentioned that DMT is testing the prediction of gas emission in machine-driven headings on the base of the INERIS method. Fig. 3 shows an excellent conformity between calculated and measured values (Tauzide et al., 1992).Fig. 3. Comparison between calculated and measured values of gas emission.煤礦井下瓦斯涌出控制摘要：一種先進(jìn)的方法已在與煤礦井下瓦斯涌出極其相關(guān)的領(lǐng)域獲得。雖然如此，卻仍然需要進(jìn)一步對(duì)方法進(jìn)行改進(jìn)，如預(yù)測(cè)瓦斯涌出量，選擇最合適的盤區(qū)設(shè)計(jì)，延長(zhǎng)預(yù)抽放瓦斯系統(tǒng)，進(jìn)一步優(yōu)化生產(chǎn)中抽放瓦斯系統(tǒng)，在在后退式開采時(shí)控制瓦斯涌出，以及預(yù)防瓦斯突出。介紹和批判性的評(píng)價(jià)這些重要問(wèn)題的研究成果。介紹已回采和未回采長(zhǎng)壁工作面的瓦斯涌出量預(yù)測(cè)方法。已開采煤層的瓦斯涌出量和巷道瓦斯涌出量的預(yù)測(cè)方法也被提及但未深入研究。對(duì)通風(fēng)的要求取決于預(yù)測(cè)結(jié)果，制定基于瓦斯抽放的最佳現(xiàn)有風(fēng)流分配方案。已開采煤層的瓦斯抽放，同預(yù)抽放一樣，不用使用抽風(fēng)機(jī)，而是通過(guò)從上面或下面進(jìn)入煤層來(lái)進(jìn)行。但有時(shí)這種簡(jiǎn)單的方法不是非常合適或有效，這時(shí)將會(huì)需要內(nèi)接縫鉆孔，同時(shí)會(huì)較長(zhǎng)時(shí)間的使用抽風(fēng)機(jī)，這是由歐洲深煤層的低滲透性決定的。解釋影響不同排瓦斯方法效率的主要因素。傳統(tǒng)的瓦斯抽放技術(shù)，無(wú)論從鉆眼和設(shè)備，以及鉆孔的幾何參數(shù)和操作的整體系統(tǒng)上都有較大的改進(jìn)空間。通過(guò)基于巷道抽放或長(zhǎng)而直徑大的鉆孔抽放的瓦斯抽放系統(tǒng)裝置能夠達(dá)到改善控制后退式開采工作面末端瓦斯涌出的目的。這種方法能在非常困難的情況下安全實(shí)施。另一種方法是從采空區(qū)傾斜式抽出瓦斯。在德國(guó)瓦斯突出以“非典型性”突出為主要形式，即突然釋放大量瓦斯。這個(gè)領(lǐng)域的最新研究成果將這些現(xiàn)象分為五類，適用于他們的早期檢測(cè)和預(yù)防措施也被提到。關(guān)鍵詞：瓦斯涌出 預(yù)測(cè) 預(yù)先脫氣 瓦斯抽放 瓦斯突出1 概述煤的沉積物包括瓦斯（主要成分為甲烷），其數(shù)量受煤化程度和地表巖層透氣性的影響。這就是在德國(guó)為何瓦斯在煤層（以及巖層）的含量，從在西北部Ruhr Basin礦中的長(zhǎng)焰煤含量為0m3/t到在Ibbenbren礦中的無(wú)煙煤含量大于25m3/t的原因。 受采礦活動(dòng)的影響，瓦斯擴(kuò)散進(jìn)礦井。為了更好的理解這個(gè)過(guò)程，需要區(qū)分基本的瓦斯涌出和附加的瓦斯涌出?；就咚褂砍鍪侵竿咚箯拈_采煤層涌出，其等價(jià)于在多層沉積物中的部分涌出和在單層沉積物中的全部涌出。附加瓦斯涌出是指相鄰煤層（就多層沉積物而言）和連接巖層的瓦斯涌出。附加瓦斯涌出量可能會(huì)超過(guò)基本瓦斯涌出量的10倍。因此瓦斯涌出的控制措施主要由附加瓦斯涌出量決定。在德國(guó)，如果礦井空氣中的瓦斯?jié)舛仍谒邢嚓P(guān)地段始終處于1%以下，那么則認(rèn)為瓦斯涌出量在控制之中。這個(gè)值離甲烷空氣混合氣體的爆炸下限有足夠的距離，在正常情況下當(dāng)達(dá)到甲烷空氣混合氣體的爆炸下限時(shí)甲烷的含量為4.4%，在礦井中甲烷濃度的極限值可允許達(dá)到1.5%。由于歷史的原因，其他的國(guó)家有時(shí)會(huì)使用不同的極限值，如在英國(guó)礦井中甲烷允許的極限值為1.25%，在德國(guó)則為2%?？刂仆咚褂砍龅姆椒ɑ救缦拢海?）總體上避免瓦斯從沉積物中釋放。這在僅考慮附加瓦斯涌出或采煤過(guò)程不影響穩(wěn)定性時(shí)才有可能。（2）在開采之前從沉積物中除去瓦斯。為了這個(gè)目的，所有自然的或人為的預(yù)先脫氣的方法，無(wú)論是通過(guò)通風(fēng)，還是從地表打斜交叉測(cè)量鉆孔，以及從地下打內(nèi)接縫鉆孔，在技術(shù)上都是合理的。（3）煤礦生產(chǎn)期間，在瓦斯與空氣流混合之前對(duì)其進(jìn)行捕捉和抽放。這是為了使用抽放鉆孔，抽放巷道或抽房峒室進(jìn)行瓦斯捕捉而發(fā)展起來(lái)的經(jīng)典方法。（4）用足量的空氣將瓦斯流稀釋后再將其均質(zhì)和疏散。這涉及到盤區(qū)設(shè)計(jì)、空氣供應(yīng)、空氣分配、以及預(yù)防瓦斯突出。接下來(lái)的討論將集中于在歐盟提供基金的研究中現(xiàn)在優(yōu)先給予考慮的問(wèn)題。這其中也包括世界上有關(guān)瓦斯涌出問(wèn)題的重要部分。就筆者許可的范圍內(nèi)，來(lái)自非歐盟國(guó)家（如澳大利亞、獨(dú)聯(lián)體、南非、美國(guó)）的問(wèn)題也將被考慮。本文主題的提出是基于對(duì)以下幾個(gè)標(biāo)題的考慮：瓦斯涌出量預(yù)測(cè)、考出瓦斯涌出的措施、煤層預(yù)先脫氣、常規(guī)瓦斯抽放技術(shù)的優(yōu)化、后退式開采瓦斯涌出的控制、瓦斯突出的預(yù)測(cè)。2 瓦斯涌出預(yù)測(cè)甲烷涌出量預(yù)測(cè)在德國(guó)硬煤工業(yè)已經(jīng)實(shí)踐了很多年(Winter, 1958; Schulz, 1959; Noack, 1970 and Noack, 1971; Flgge, 1971; Koppe, 1975)。所以現(xiàn)在已經(jīng)得到了一些預(yù)測(cè)方法。下面將介紹其中的一些：（1）瓦斯涌出量的估算(Koppe, 1976; Noack, 1985)，就像用于處理已采煤層和鄰近煤層的涌出一樣，已被先前的采煤活動(dòng)干擾。（2）瓦斯壓力減少量的估算(Noack and Janas, 1984; Janas, 1985a and Janas, 1985b)同樣地被應(yīng)用于沉積物的未開采部分中。（3）長(zhǎng)壁工作面的已采煤層的瓦斯涌出預(yù)測(cè)方法，掘進(jìn)巷道瓦斯涌出預(yù)測(cè)方法以及在鉆孔時(shí)被斜穿的煤層的瓦斯涌出預(yù)測(cè)方法。前兩種方法是預(yù)測(cè)礦井具體瓦斯涌出量的方法，用平均生產(chǎn)一噸煤涌出的瓦斯立方米數(shù)來(lái)表示。單位時(shí)間內(nèi)瓦斯涌出的立方米數(shù)，可通過(guò)預(yù)測(cè)結(jié)果乘以預(yù)計(jì)產(chǎn)生體積得到，它是制定煤礦計(jì)劃的一個(gè)重要因素。這些方法確定了在相當(dāng)長(zhǎng)的時(shí)間內(nèi)（幾個(gè)月）以幾乎相同的工作面掘進(jìn)速度工作時(shí)采煤工作面的平均瓦斯涌出量。這種預(yù)測(cè)假定瓦斯涌出的區(qū)域已經(jīng)被全面開拓，也就是說(shuō)采煤工作面的開始階段已經(jīng)過(guò)去。此外，采煤工作面長(zhǎng)度必須大于臨界長(zhǎng)度（即工作面600m深時(shí)，其長(zhǎng)度要大于180190m,1000m深時(shí)，其長(zhǎng)度要大于220-240m）。涌進(jìn)采煤工作面區(qū)域（包括進(jìn)入井下風(fēng)流和瓦斯抽放設(shè)備）的瓦斯受以下因素的限制：（1）在工作面頂板和底板內(nèi)瓦斯涌出區(qū)域的幾何形狀和尺寸，包括該區(qū)域內(nèi)瓦斯走向?qū)拥暮穸群蛿?shù)量；（2）瓦斯走向?qū)拥耐咚购浚唬?）瓦斯涌出程度；（4）采煤活動(dòng)的強(qiáng)度。附加瓦斯涌出區(qū)域的幾何形狀和尺寸被簡(jiǎn)化為位于開采工作面上側(cè)和下側(cè)的平行六面體。它距煤層的平均距離取決于預(yù)測(cè)方法。附加瓦斯涌出區(qū)域內(nèi)煤層的數(shù)量、位置、種類以及厚度可通過(guò)地面鉆孔，喑井-豎井，連接煤層的平巷來(lái)得到。煤層瓦斯含量很難確定。對(duì)于直接從煤層中獲取瓦斯含量有兩種方法可供選擇（Verlag Glckauf GmbH, 1987）。一種方法利用從內(nèi)接縫鉆孔鉆取得煤樣得到（已開拓煤層），另一種方法利用連接煤層的地面鉆孔內(nèi)的巖心樣品得到（未開拓煤層）。因?yàn)闆](méi)有一種合適的方法確定巖石中的瓦斯含量，一種雙重預(yù)測(cè)方法被應(yīng)用，第一種預(yù)測(cè)忽略所有巖石，第二種預(yù)測(cè)應(yīng)用一種預(yù)測(cè)巖層瓦斯含量的假想。預(yù)測(cè)涌出瓦斯占瓦斯含量比例的方法基本上存在分歧。一方面，基于瓦斯涌出程度的預(yù)測(cè)方法假定涌出瓦斯量與瓦斯原始含量有關(guān)也與接近采煤工作面區(qū)域相關(guān)煤層的幾何位置有關(guān)。另一種方法，依靠瓦斯壓力，利用瓦斯涌出后的瓦斯壓力得到殘余的瓦斯量。它的結(jié)果取決于煤層的幾何位置。這也就是說(shuō)涌出的瓦斯量占瓦斯含量的比例與原始瓦斯含量無(wú)關(guān)，而主要取決于后者。3 已回采條件下的預(yù)測(cè) 預(yù)測(cè)薄及中厚傾斜煤層先前開采區(qū)域的長(zhǎng)壁工作面中瓦斯總量的方法取決于瓦斯涌出程度(圖1) 。用PFG表示頂板瓦斯涌出程度曲線（考慮0.016的衰減系數(shù)），用FGK表示底板瓦斯涌出曲線。出于實(shí)際的原因，瓦斯涌出區(qū)域的上部邊界被設(shè)定為+165米，下部邊界被設(shè)定為-59米。在缺乏經(jīng)驗(yàn)數(shù)據(jù)的情況下，已開采煤層的瓦斯涌出程度被設(shè)定為75%。在煤層之上，從高度為0米到+20米，在煤層之下，從高度0米到-11米，瓦斯涌出程度被設(shè)定為100%。為了預(yù)測(cè)方便，巖層周圍被假想為煤層，并且煤層的瓦斯含量被認(rèn)為是減少了的。泥巖中的減少系數(shù)為0.019，沙頁(yè)巖的減少系數(shù)為0.058，砂巖中的減少系數(shù)為0.096。1.3未回采條件下的預(yù)測(cè)預(yù)測(cè)未回采區(qū)域長(zhǎng)壁工作面瓦斯總量的方法是以殘余瓦斯壓力的基本情況為基礎(chǔ)的（圖2）。由圖可知，在頂板有三個(gè)區(qū)域，底板有兩個(gè)區(qū)域，他們呈現(xiàn)出不同的殘余瓦斯壓力梯度。 upper boundary 上部邊界 weakened zone 減弱區(qū) cleaved zone 黏著區(qū) caved zone 陷落區(qū) loosened 疏松區(qū) lower boundary 下部邊界 residual gas pressure in bar 殘余瓦斯壓力（bar）以殘余瓦斯基本情況的圖例為基礎(chǔ)，殘余瓦斯壓力根據(jù)每一層距離開采煤層的平均一般距離一層層確定，然后使用Langmuir等溫吸附式轉(zhuǎn)化為殘余瓦斯含量。由原始瓦斯含量和殘余瓦斯含量的差異最終得到吸附瓦斯的涌出比例，吸附瓦斯量是需要得到的值。然后這個(gè)值與游離瓦斯量相加，游離瓦斯量的比例由修正后煤層的有效孔隙率乘以煤層厚度和煤層瓦斯壓力的差得到。經(jīng)驗(yàn)值用于煤和巖石有效孔隙中的甲烷。典型值在煤中為1%-10%，在巖石中為0.3%-1.3%。這個(gè)值在不同的范圍內(nèi)變化。在沒(méi)有開采煤層瓦斯涌出比例的經(jīng)驗(yàn)值時(shí)，這個(gè)值將被設(shè)定為40%。2.3兩種方法的比較 基于瓦斯涌出程度的瓦斯壓力預(yù)測(cè)方法有以下優(yōu)點(diǎn)：瓦斯涌出區(qū)域沒(méi)有嚴(yán)格的上部和下部邊界。他們主要依靠原始瓦斯壓力值和巖層種類。在頂板，殘余瓦斯壓力被認(rèn)為會(huì)影響開采煤層的厚度。不僅預(yù)測(cè)了吸附瓦斯量，而且還預(yù)測(cè)了游離瓦斯量；不僅預(yù)測(cè)了煤層瓦斯量，而且還預(yù)測(cè)了巖層瓦斯量。在預(yù)測(cè)中應(yīng)用到了瓦斯總量，而沒(méi)有應(yīng)用解吸瓦斯比例。2.4其他方法 長(zhǎng)壁工作面已開采煤層瓦斯涌出量以及在隧道掘進(jìn)機(jī)鉆孔期間對(duì)內(nèi)接縫-平巷和煤層進(jìn)行斜穿孔操作時(shí)的瓦斯涌出量的預(yù)測(cè)不能被詳細(xì)的解釋。進(jìn)一步的了解需要參閱以下論文：Noack, 1977; Janas and Stamer, 1987; Noack and Janas, 1988; Noack and Opahle, 1992. 應(yīng)該提到的是，DMT正在以INERIS方法為基礎(chǔ)對(duì)機(jī)掘工作面瓦斯涌出量預(yù)測(cè)方法進(jìn)行測(cè)試。圖3顯示預(yù)測(cè)值和測(cè)量值非常相似。Measured 測(cè)量 calculated 預(yù)測(cè) advance 掘進(jìn)Volume of CH4 release CH4釋放體積