專業(yè)英語(yǔ)9-10課件

1、The Professional EnglishThe Professional English何何 寧寧何 寧LESSON 9LESSON 9Open FiresOpen Fires明明 火火何 寧教學(xué)內(nèi)容教學(xué)內(nèi)容Introduciton、Oxygen-rich and fuel-rich fires、Effects of fires on ventilation、 Methods of fighting open fires何 寧教學(xué)目的教學(xué)目的通過該部分學(xué)習(xí)，conflagration大火, 大火災(zāi), 突發(fā)、compressor 壓縮機(jī)、thrower【軍】投擲器, 噴射器, 發(fā)射器、c

2、ombustible 易燃物；可燃物、earth 電接地、smouldering悶燒, 低溫?zé)捊? 低溫干餾、propagation 蔓延、proliferate 增生蔓延、distilled由蒸餾得來的、conveyor 運(yùn)輸機(jī)、gearhead 機(jī)頭、sprinkler system自動(dòng)噴水消防系統(tǒng)、high expansion foam 高倍膨脹泡沫等專業(yè)詞匯，達(dá)到英文與中文相互熟練翻譯的程度；深入理解Introduciton 、Methods of fighting open fires等內(nèi)容，達(dá)到熟練閱讀和正確、通順地翻譯的程度；了解Oxygen-rich and fuel-rich

3、 fires、Effects of fires on ventilation等內(nèi)容，達(dá)到比較熟練和比較通順翻譯的程度。何 寧 教學(xué)重點(diǎn)、難點(diǎn)教學(xué)重點(diǎn)、難點(diǎn) Methods of fighting open fire 課時(shí)安排課時(shí)安排 1.5 授課方法授課方法 講授與討論相結(jié)合何 寧復(fù)習(xí)舊課復(fù)習(xí)舊課1回憶porosity 、permeability、adsorption isotherm專業(yè)詞匯的中文含義；自由狀態(tài)瓦斯、吸附狀態(tài)瓦斯、瓦斯抽放英文表達(dá)。2Which factors are related to porosity? porosity? (rank, gas composition

4、and gas pressure.)3. Whats the relationship betwteen sorptivesorptive capacity and rank of the coal and depth?何 寧IntroductionIntroductionFires that occur in mine airways usually commence from a single point of ignition. The initial fire is often quite small and, indeed, most fires are extinguished r

5、apidly by prompt local action. Speed is of the essence. An energetic ignition that remains undetected, even for only a few minutes, can develop into a conflagrationconflagration that becomes difficult or impossible to deal with. Sealing off the district or mine may then become inevitable.發(fā)生在礦井風(fēng)巷中的火災(zāi)

6、通常開始于一點(diǎn)的燃燒。最初火勢(shì)非常小，實(shí)際上只要能夠及時(shí)地進(jìn)行局部處理，大多數(shù)火災(zāi)都能被立即撲滅。快速的行動(dòng)是非常重要的。旺盛的燃燒如果未被發(fā)現(xiàn)，那么即使只有幾分鐘，也能夠發(fā)展為大火，從而很難或者不可能撲滅了。因而，封閉區(qū)域或者整個(gè)礦井可能變得不可避免了。何 寧Open FiresOpen FiresThe rate at which an open fire develops depends, initially, upon the heat produced from the igniting source. A fine spray of burning oil from a damag

7、ed air compressorcompressor can be like a flame throwerthrower and ignite nearby combustiblecombustibles within seconds. On the other hand, an earthearth leakage from a faulty cable may cause several hours of smoulderingsmouldering before flames appear. The further propagationpropagation of the fire

8、 depends upon the availability of fuel and oxygen. A machine fire in an untimbered metal mine airway will remain localized if there is little else to burn in the vicinity. Conversely, an airway that is heavily timbered or with coal surfaces in the roof, floor or sides will provide a ready path for s

9、peedy development and propagation of a fire.何 寧Open FiresOpen Fires明火發(fā)展的速度，最初取決于點(diǎn)火源產(chǎn)生的熱量。從損壞的空氣壓縮機(jī)中噴出纖細(xì)的燃燒油的飛沫就如同火焰噴射器一樣，幾秒內(nèi)就能點(diǎn)燃附近的可燃物。另一方面，有故障的電纜造成的接地漏電可能在幾個(gè)小時(shí)的低溫干餾后才出現(xiàn)火焰?；馂?zāi)能夠進(jìn)一步蔓延取決于燃料和氧氣的可利用性。如果臨近可燃物很少，在沒有木材的金屬礦山巷道中發(fā)生的機(jī)械火災(zāi)將停留在局部地區(qū)。相反，如果風(fēng)巷中木材很多或者頂?shù)装寮八闹芏加忻?，那么發(fā)生火災(zāi)時(shí)發(fā)展速度快，能夠進(jìn)一步蔓延。注：Vicinity：附近何 寧Open

10、FiresOpen FiresWhen an open fire has developed to the extent of causing a measurable change in the temperature of the airflow then it can affect the magnitudes and distributions of flow within the mine ventilation system. Conversely, the availability of oxygen to the fire site controls the developme

11、nt of the fire. This Section discusses the coupled interaction between fire propagation and ventilation, and the means by which open fires in mines may be fought.當(dāng)明火發(fā)展到可以測(cè)得氣流溫度發(fā)生變化時(shí)的程度，那么明火將影響礦山通風(fēng)系統(tǒng)中風(fēng)量的大小和分布。相反，減少提供給火災(zāi)地點(diǎn)氧氣能控制火災(zāi)的發(fā)展。本部分討論了火災(zāi)蔓延和通風(fēng)之間的相互關(guān)系，和撲滅礦山火災(zāi)的方法。注：coupled 連接的何 寧Oxygen-rich and fuel-

12、rich firesOxygen-rich and fuel-rich firesAt the start of most open fires in ventilated areas, there is a plentiful supply of oxygen -more than sufficient for combustion of the burning material. Indeed, if the air velocity is brisk then heat may be removed at a rate greater than that at which it is p

13、roduced. The heat side of the fire triangle is removed and the fire is blown out. These are examples of oxygen-rich fires. Assuming that the fire continues to proliferate,proliferate, it will consume increasing amounts of oxygen and, at the same time, produce greater volumes of distilleddistilled ga

14、ses and vapours. The point may be reached when the heat of combustion produces temperatures that continue to remain high enough to distill gases and vapours from the coal, timber or other available fuels but with insufficient oxygen to burn those gases and vapours completely. The fire has then becom

15、e fuel-rich.何 寧氧氣充足火災(zāi)和燃料充足火災(zāi)氧氣充足火災(zāi)和燃料充足火災(zāi)通風(fēng)區(qū)域發(fā)生的大部分明火，初期提供的氧氣充足，多于正在燃燒著的物質(zhì)所需的氧氣。實(shí)際上，如果風(fēng)流速度很快，那么帶走熱量的速度比產(chǎn)生熱量的速度要快。火災(zāi)三角形熱量方面將消除，火災(zāi)會(huì)被吹滅。這些是氧氣充?；馂?zāi)的例子。假定火災(zāi)繼續(xù)擴(kuò)散，將消耗越來越多的氧氣，同時(shí)，生成較多的由蒸餾而來的氣體和水蒸氣。將會(huì)達(dá)到這種程度：燃燒熱提供的溫度一直很高，足以從煤、木材和其它可利用燃料蒸餾出氣體和水蒸氣；但是提供的氧氣不充足，不能充分燃燒這些氣體和蒸氣。這種類型的火災(zāi)就成為燃料充足的火災(zāi)。何 寧Effects of fires on

16、ventilationEffects of fires on ventilationAn open fire causes a sharp increase in the temperature of the air. The resulting expansion of the air produces two distinct effects. First the expansion attempts to take place in both directions along the airway. The tendency to expand against the prevailin

17、g direction produces a reduction in the airflow. This is known as the choke or throttle effect. Secondly, the decreased density results in the heated air becoming more buoyant and causes local effects as well as changes in the magnitudes of natural ventilating energy.何 寧火災(zāi)對(duì)通風(fēng)的影響火災(zāi)對(duì)通風(fēng)的影響明火引起空氣的溫度急劇上升

18、。因而引起的空氣膨脹產(chǎn)生兩個(gè)顯著的影響。第一，膨脹試圖發(fā)生在沿風(fēng)道的兩個(gè)方向。逆著主流方向膨脹的趨勢(shì)造成風(fēng)量的減小。這被稱為窒息作用。第二，密度的減小使熱空氣變得更輕，產(chǎn)生局部影響，并且引起自然通風(fēng)能量的變化。resulting：作為結(jié)果的，因而發(fā)生的何 寧Methods of fighting open firesMethods of fighting open firesThe majority of open fires can be extinguished quickly if prompt action is taken. This underlines the importanc

19、e of fire detection systems, training, a well-designed firefighting system and the ready availability of fully operational firefighting equipment. Fire extinguishers of an appropriate type should be available on vehicles and on the upstream side of all zones of increased fire hazard. These include s

20、torage areas and fixed locations of equipment such as electrical or compressor stations and conveyor gearheadconveyor gearheads.何 寧撲滅明火的方法撲滅明火的方法如果及時(shí)行動(dòng)，大部分明火都能夠撲滅?；馂?zāi)探測(cè)系統(tǒng)、培訓(xùn)、設(shè)計(jì)良好的滅火系統(tǒng)和現(xiàn)成的能充分運(yùn)行的滅火設(shè)備很重要。合適型號(hào)的滅火器應(yīng)安置在車輛上面和火災(zāi)危險(xiǎn)大的所有區(qū)域的逆流側(cè)。這包括儲(chǔ)藏室區(qū)域和設(shè)備的固定安裝位置（例如電站或壓縮機(jī)站和運(yùn)輸機(jī)的傳送機(jī)頭）。何 寧Methods of fighting open f

21、iresMethods of fighting open firesNeither water nor foam should be used where electricity is involved until it is certain that the power has been switched off. Fire extinguishers that employ carbon dioxide or dry powders are suitable for electrical fires or those involving flammable liquids.電力火災(zāi)既不能用

22、水也不能用泡沫滅火，除非確定電源已關(guān)。使用二氧化碳或干粉的滅火器適于撲滅電力火災(zāi)或易燃液體火災(zāi)。何 寧Methods of fighting open firesMethods of fighting open firesDeluge and sprinkler systemsprinkler systems can be very effective in areas of fixed equipment, stores and over conveyors. These should be activated by thermal sensors rather than smoke or

23、gas detectors in order to ensure that they are operated only when open combustion occurs in the near vicinity.洪水和自動(dòng)噴水系統(tǒng)在固定設(shè)備、儲(chǔ)藏室和輸送機(jī)上面這些地區(qū)很有效。這些裝置要激活應(yīng)通過熱力探測(cè)器而不是煙霧或瓦斯探測(cè)器，以確保只有當(dāng)在鄰近地區(qū)發(fā)生明火燃燒時(shí)才自動(dòng)運(yùn)轉(zhuǎn)。何 寧Methods of fighting open firesMethods of fighting open firesThe two direct methods of firefighting intro

24、duced in this Section involve the application of water and high expansion foamhigh expansion foam.本部分介紹的兩種直接滅火方法是用水和高倍膨脹泡沫。何 寧Firefighting with waterFirefighting with waterExcept where electricity or flammable liquids are involved, water is the most common medium of firefighting. When applied to a b

25、urning surface, water helps to remove two sides of the fire triangle. The latent heat of the water as it vapourises and the subsequent thermal capacity of the water vapour assist in removing heat from the burning material. Furthermore, the displacement of air by water vapour and the liquid coating o

26、n cooler surfaces help to isolate oxygen from the fire.何 寧用水滅火用水滅火除了電力和可燃液體火災(zāi)外，水是滅火最常用的方法。當(dāng)水應(yīng)用在燃燒著表面時(shí)，它有助于消除火災(zāi)三角形的兩個(gè)方面。水蒸發(fā)時(shí)具有的潛在熱能和隨后水蒸氣的熱力能幫助消除燃燒物質(zhì)的熱能。此外，水蒸氣取代空氣并且液體在較涼的表面形成覆蓋層，這有助于隔絕氧氣何 寧High expansion foamHigh expansion foamLarge volumes of water-based foam provide a valuable tool for fighting fi

27、res in enclosed spaces such as the basements of buildings or in the holds of ships. It has been employed for mine fires since at least 1956 (Eisner). The method is employed on large fires and, although it has had somewhat limited success in extinguishing mine fires, it can play a valuable role in co

28、oling and quenching an area to an extent that allows firefighters with hoses to approach closer to the firefront. Even when sealing an area has become inevitable, valuable time for rescue operations can be bought by employing high expansion foam.何 寧New Word and ExpressionsNew Word and Expressionscon

29、flagration大火, 大火災(zāi), 突發(fā)compressor 壓縮機(jī)thrower【軍】投擲器, 噴射器, 發(fā)射器combustible 易燃物；可燃物earth 電接地smouldering悶燒, 低溫?zé)捊? 低溫干餾propagation 蔓延proliferate 增生蔓延distilled由蒸餾得來的conveyor 運(yùn)輸機(jī)gearhead 機(jī)頭sprinkler system自動(dòng)噴水消防系統(tǒng)high expansion foam 高倍膨脹泡沫何 寧QuestionsQuestionsAssignmentAssignmentPlease translate the last two

30、paragraphs of this text into Chinese.何 寧LESSON 10LESSON 10 Spontaneous CombustionSpontaneous Combustion自自 燃燃 教學(xué)內(nèi)容教學(xué)內(nèi)容 Introduction Introduction 、The phases of oxidation The phases of oxidation 、Susceptibility to Susceptibility to spontaneous combustionspontaneous combustion、Precautions against spont

31、aneous combustionPrecautions against spontaneous combustion 教學(xué)目的教學(xué)目的 通過該部分學(xué)習(xí)，要求學(xué)生熟記通過該部分學(xué)習(xí)，要求學(xué)生熟記sulphide sulphide 硫化物、硫化物、inhabit inhabit 阻止反阻止反應(yīng)，減慢（反應(yīng)的）速度、應(yīng)，減慢（反應(yīng)的）速度、oxidation oxidation 氧化作用、氧化作用、SHT -self-heating SHT -self-heating temperature temperature 最低自熱溫度、最低自熱溫度、exothermic exothermic 化化 發(fā)熱

32、的發(fā)熱的, , 放出熱量的、放出熱量的、chemisorption chemisorption 化學(xué)吸附作用、化學(xué)吸附作用、peroxy-complexe peroxy-complexe 過化合物、過化合物、oxalic acid oxalic acid 草酸草酸、aromatic acid aromatic acid 芳香酸、芳香酸、gobstinkgobstink采空區(qū)臭味、采空區(qū)臭味、Incineration Incineration 燒成灰、燒成灰、susceptibility to spontaneous combustionsusceptibility to spontaneous

33、 combustion自燃傾向性、自燃傾向性、petrology petrology 巖石學(xué)、巖石學(xué)、adiabatic adiabatic 物物 絕熱的絕熱的, , 隔熱的、隔熱的、goaf (gob) goaf (gob) 采空區(qū)、采空區(qū)、friability friability 脆性、脆性、winningwinning【礦礦】開采開采; ; 備采煤區(qū)、備采煤區(qū)、pillar pillar 支柱、支柱、per centage extraction per centage extraction 開采百開采百分率、分率、multi-lift multi-lift 多分層、多分層、caving

34、 miningcaving mining崩落開采法、崩落開采法、gradient gradient 傾斜度等專業(yè)傾斜度等專業(yè)詞匯，達(dá)到英文與中文相互熟練翻譯的程度；深入理解詞匯，達(dá)到英文與中文相互熟練翻譯的程度；深入理解The phases of oxidation The phases of oxidation 、Susceptibility to spontaneous combustionSusceptibility to spontaneous combustion等內(nèi)容，達(dá)到熟練閱讀和正確、等內(nèi)容，達(dá)到熟練閱讀和正確、通順地翻譯的程度；了解通順地翻譯的程度；了解Precautions

35、 against spontaneous combustionPrecautions against spontaneous combustion等內(nèi)容等內(nèi)容，達(dá)到比較熟練和比較通順翻譯的程度。，達(dá)到比較熟練和比較通順翻譯的程度。 教學(xué)重點(diǎn)、難點(diǎn)教學(xué)重點(diǎn)、難點(diǎn) Susceptibility to spontaneous combustion Susceptibility to spontaneous combustion何 寧一、復(fù)習(xí)舊課一、復(fù)習(xí)舊課1回憶smouldering 、distilled專業(yè)詞匯的中文含義；大火（conflagration）、易燃物；可燃物combustible 英

36、文表達(dá)。2Please describe Effects of fires on ventilationin English.(produces a reduction in the airflow; causes local effects as well as changes in the magnitudes of natural ventilating energy.)何 寧二、教授新課二、教授新課IntroductionIntroductionWhen air is allowed to percolate through many organic materials includi

37、ng coal then there will be a measurable rise in temperature. The same phenomenon can be observed in crushed sulphidesulphide ores and is caused by a progressive series of adsorptive, absorptive and chemical processes. These produce heat and an observable elevation in temperature. The percolating air

38、flow will, therefore, remove that heat increasingly as the temperature of the material rises. If the leakage airflow is sufficiently high then a balanced equilibrium will be reached at which the rate of heat removal is equal to the rate at which heat is produced; the temperature will stabilize. The

39、process will also reach an air-constrained equilibrium if the airflow is sufficiently low to inhibitinhibit the oxidation oxidation processes. However, between these two limits there is a dangerous range of percolating air flows that will encourage spontaneous heating.何 寧當(dāng)空氣滲透到許多有機(jī)物質(zhì)中（包括煤）時(shí)，那么可以測(cè)得溫度

40、會(huì)上升。在壓碎的硫化物礦石上可以觀察到同樣現(xiàn)象，這是由一系列逐漸進(jìn)行的吸附、吸附性的和化學(xué)過程引起的。這些過程產(chǎn)生熱，并且可以觀察到溫度的升高。由于物質(zhì)溫度的升高，產(chǎn)生越來越多的熱量，而滲透的風(fēng)量能把這些熱量帶走。如果漏風(fēng)量足夠多，那么就會(huì)形成一種平衡狀態(tài)：熱量移去的速度與熱量產(chǎn)生的速度相等；溫度將恒定。如果風(fēng)量足夠低以至于抑制了氧化作用，同樣會(huì)達(dá)到一種空氣抑制的平衡態(tài)。然而，滲透的風(fēng)量在這兩界限之間時(shí)，是危險(xiǎn)的，能夠促進(jìn)自發(fā)熱的產(chǎn)生。何 寧Each material that is liable to spontaneous combustion has a critical tempera

41、ture known as the minimum self-heating temperature (SHT). This is the lowest temperature that will produce a sustained exothermicexothermic reaction or thermal runaway. Hence, if the temperature reaches the SHT before thermal equilibrium is attained then the oxidation process will accelerate. The te

42、mperature will escalate rapidly, encouraging even higher rates of oxidation until the material becomes incandescent. At this stage, smoke and gaseous products of combustion appear in the subsurface ventilation system. The mine then has a concealed fire. The primary dangers of such occurrences are th

43、e evolution of carbon monoxide, the ignition of methane and combustion progressing into airways to produce open fires.何 寧每種易于自燃的物質(zhì)都有一個(gè)臨界溫度，被稱為最低自熱溫度(SHT)（燃點(diǎn)）。最低自熱溫度是能夠產(chǎn)生持續(xù)的放熱反應(yīng)或者熱失控的最低溫度。因此，如果在熱平衡前，達(dá)到最低自熱溫度時(shí)，氧化作用會(huì)加快。溫度會(huì)迅速地上升，使氧化速度更快，直到物質(zhì)變成灼熱的。在這個(gè)階段，燃燒產(chǎn)生的煙和氣態(tài)物質(zhì)出現(xiàn)在地下通風(fēng)系統(tǒng)中。那么，礦山形成一種隱蔽火。這種現(xiàn)象的主要危害是：CO的形成

44、；引起瓦斯的燃燒；燃燒發(fā)展到巷道中產(chǎn)生明火。何 寧The phases of oxidationThe phases of oxidation氧化階段氧化階段The oxidation processes of coal occur in four stages (Banerjee, 1985).氧化過程包括四個(gè)階段 (Banerjee, 1985).1. Physical adsorption of oxygen commences at a temperature of about -80 degrees C and is reversible but diminishes rapidly

45、 as the temperature increases to become negligible beyond 30 to 50 degrees C. The process of adsorption produces heat as a by-product of the modified surface energy of the material. This causes the initial rise in temperature.氧的物理吸附開始于溫度大約在-80度左右，并且是可逆的。但是，當(dāng)溫度升高到超過30度至50度時(shí)，物理吸附迅速減小，變得可以忽略。吸附過程產(chǎn)生的熱是物

46、質(zhì)表面能量改變的副產(chǎn)品。這引起溫度的初始變化。（潛伏期）何 寧2. Chemical absorption (known also as chemisorptionchemisorption or activated sorption) becomes significant at about 5 degrees C. This progressively causes the formation of unstable compounds of hydrocarbons and oxygen known as peroxy-complexeperoxy-complexes. 溫度在5度左右，

47、化學(xué)吸附（稱為化學(xué)吸附作用或者活性吸附作用）成為主要的作用。這引起越來越多的活躍的烴類和氧類化合物（稱為過化合物）的生成。（自熱階段）何 寧3. At a temperature which appears to approximate to the self-heating temperature (SHT) of the coal, the peroxy-complexes decompose at an accelerating rate to provide additional oxygen for the further stages of oxidation. This occu

48、rs within the range of approximately 50 to 120 degrees C with a typical value of 70 degrees C. At higher temperatures, the peroxy-complexes decompose at a greater rate than they are formed (Chakravorty, 1960) and the gaseous products of chemical reaction appear - in particular, carbon monoxide, carb

49、on dioxide, water vapour, and the oxalic acidoxalic acids, aromatic aromatic acidacids and unsaturated hydrocarbons that give the characteristic odour of gobstinkgobstink .當(dāng)煤溫度接近燃點(diǎn)時(shí)，過化合物加速分解，為氧化的進(jìn)一步過程提供了額外的氧氣。這發(fā)生在溫度大約在50120度的范圍內(nèi)，最典型的是70度。如果溫度更高，過化合物分解的速度比形成的速度要快，化學(xué)反應(yīng)生成的氣態(tài)物質(zhì)就會(huì)出現(xiàn)（特別如一氧化碳、二氧化碳、水蒸氣、草酸、芳

50、香酸和不飽和的烴類，這具有典型的“采空區(qū)臭味”）（自熱階段）何 寧4. When the temperature exceeds some 150 degrees C, the combustion process accelerates rapidly. IncinerationIncineration of the coal occurs with escalating emissions of the gaseous products of combustion.當(dāng)溫度超過大約150度時(shí)，燃燒過程迅速加快。隨著燃燒釋放越來越多的氣態(tài)物質(zhì)，煤灰就會(huì)出現(xiàn)。何 寧Susceptibility

51、to spontaneous combustionSusceptibility to spontaneous combustion自燃傾向性自燃傾向性A large number of tests and indices have been devised as suggested measures of the liability of differing coals and other materials to spontaneous combustion. These have involved:人們作大量的試驗(yàn)，提出了許多指標(biāo)，建議作為鑒定煤和其他物質(zhì)自燃傾向性的方法。這包括：1. c

52、oal petrologypetrology and rank, the younger and lower ranks of coal being more susceptible煤巖石特征和品級(jí)。成巖時(shí)間越晚，品級(jí)越低，煤越易自燃。（注：易受影響的,）2. rates of oxygen consumption or temperature rise at specified phases of the oxidation process消耗氧氣的速度或在氧化過程特定階段溫度升高的程度何 寧3. self-heating temperatures (SHT) or other temper

53、atures at specified stages of the heating process燃點(diǎn)或加熱過程特定階段的其他溫度4. rates of heat production during isothermal or adiabaticadiabatic tests.在等溫或絕熱實(shí)驗(yàn)中產(chǎn)熱速度何 寧No such test or index has been found to have universal application. The difficulty is that susceptibility to spontaneous combustion depends not o

54、nly upon the material but also its physical state as well as the psychrometric condition and migration paths of the leakage airflows, the latter depending, in turn, upon the mining methods and layout. The matters of additional relevance are:這些實(shí)驗(yàn)或指標(biāo)沒有一個(gè)能得到普遍運(yùn)用。普遍運(yùn)用的困難在于：自燃傾向性不僅取決于物質(zhì)本身而且還取決于物理狀態(tài)、濕度條件和

55、漏風(fēng)移動(dòng)通道，而后面因素依次取決于開采方法布置。這些附加因素有：何 寧1. amount and degree of comminution of crushed material left in the goaf (gob)goaf (gob) area, these depending upon friabilityfriability of coaltype of coal winningwinning machineefficiency of coal clearanceroof, floor or pillarpillar coal left (per centage per cen

56、tage extractionextraction)thickness of seams and need for multi-liftmulti-lift or caving caving mining systemmining systemsdepth and pre-stressing (microfracturing) of coalgeological disturbances何 寧1遺留在采空區(qū)中粉碎物質(zhì)的數(shù)量和粉碎程度，這取決于： 煤的脆性 采煤機(jī)械類型 煤清除效率 頂板、底板和支柱上的遺煤（開采百分率） 煤層厚度和是否需要多分層或崩落開采法 煤深和煤預(yù)應(yīng)力（微孔） 地質(zhì)干擾何

57、寧2. methods of stowing and sealing of roadsides裝載方法和巷道側(cè)的密閉方法3. gradient gradient of the seam and proximity of other seams煤層傾斜度和其他煤層鄰近度4. length of face工作面長(zhǎng)度5. rate of face advance or retreat工作面前進(jìn)或后退速度6. roof/floor stability and strata stresses in the vicinity of pillar edges, stoppings, air crossing

58、s and ventilation doors頂?shù)装宓膱?jiān)固性和支柱邊沿、風(fēng)墻、風(fēng)橋和風(fēng)門附近的層壓力何 寧7. the air pressure differential across the affected area影響區(qū)域的空氣壓力差8. the layout and resistances of surrounding airways and faces, including obstructions周圍風(fēng)巷、工作面（包括障礙物）的布置和阻力9. degree of consolidation and, hence, resistance of the caved areas壓實(shí)程度，

59、也就是塌陷區(qū)域的阻力10. the relative moisture contents of the coal and air煤和空氣的相對(duì)含濕量11. the reduction of oxygen content in the goaf (gob) areas by the emission of methane or other gases.由于采空區(qū)中甲烷和其他氣體的釋放造成氧氣含量的減少程度何 寧With this number and variety of factors it is not too surprising that efforts to characterize

60、the susceptibility of coals to spontaneous combustion purely on the basis of laboratory tests have met with rather limited success. An improved approach involves allocating weighted credit to each of the factors listed in an attempt to develop a site-specific indication of liability to spontaneous c