采煤專業(yè)外文翻譯---土壓力理論在薄煤層回填支柱設計中的應用

1、<p><b>　　翻譯部分</b></p><p><b>　　英文原文</b></p><p>　　Design of backfilled thin-seam coal pillars using earth pressure theory</p><p>　　1. Introduction</p&g

2、t;<p>　　The Self-Advancing Miner has been designed to extract coal from seams less than 90 centimeters thick. The SAM allows for extraction of the full seam height while minimizing waste rock, and utilizes remote

3、operation that allows the miner to advance up to 180m (600ft) into the seam. However, the coal seams are so thin that the recovery rates of this mining method will be fairly low and will decrease rapidly with the depth o

4、f mining. In order to increase the recovery from thin-seam mines, pillars m</p><p>　　The placing of backfill underground has predominantly been a practice employed in cut-and-fill mines (Thomas, 1979). Backf

5、ill material is introduced underground into previously mined stopes to provide a working platform and localized support, reducing the volume of open space which could potentially be filled by a collapse of the surroundin

6、g pillars (Barret et al., 1978). The presence of fill in an opening prevents large-scale movements and collapse of openings merely by occupying voids left by </p><p>　　Although the support capability of back

7、fill is well known it still remains fairly difficult to quantify. Models and equations for the determination of backfill support have been proposed (Cai, 1983; Guang-Xu and Mao-Yuan, 1983) and pillar-backfill systems hav

8、e been modeled using laboratory set-ups in order to correlate the actual support behavior of fill with proposed models (Yamaguchi and Yamatomi, 1989; Blight and Clarke, 1983; Swan and Board, 1989; Aitchison et al., 1973)

9、. But in general thes</p><p>　　2. The thin-seam coal mine</p><p>　　A thin-seam coal mine, employing the SAM technology, can be thought of as an‘underground’ highwall mine. Figure 1 depicts the s

10、implified panel geometry created by the development of entries and cross-cuts, and the system of pillars left behind after panel extraction. It is probable that the </p><p>　　cuts and cross-cuts will be angl

11、ed at approximately 60 so as to decrease the turning radius of mining equipment, but this will not effect pillar design. The length of each panel is 1200m (4000ft). The width of each panel varies with depth in order to a

12、ccommodate a barrier pillar that runs through the center of each panel. However, the panel width will be at least Greater than twice the distance required for one SAM cut,in this case 300m(1000ft).Upon extraction of the

13、panels, the barrier pillar a</p><p>　　Figure 2 is a cross-sectional view of the cutting face. The face evokes the highwall mine comparison; the coal seam runs through the middle of the panel and a portion of

14、 the panel ‘material’ is left above and below each cut. The cut width is 3m (10ft) and the cut height is equivalent to the seam height (less than 90cm (36in)). It is intended that as the SAM retreats from each cut, backf

15、ill will be either hydraulically or pneumatically placed in the mined-out void.</p><p>　　3. Application of earth pressure theory</p><p>　　The idea that the backfill support mechanism described i

16、n the previous section can be quantified using principles taken from soil mechanics is not new. A broad understanding of fill behavior has always been dependent on knowledge of earth pressures. However, earth pressure th

17、eories and concepts have not generally been considered adequate in properly quantifying the magnitude of fill support in underground mines. Limited understanding about the transfer of loads from the surrounding rock to t

18、he f</p><p>　　What makes the case of the SAM operating in a thin-seam coal mine different is the concept of ‘designed failure’ of the pillars so that deformations capable of mobilizing the passive resistance

19、 of the backfill will occur. From civil engineering design of retaining walls it has been shown that the movement required to reach maximum passive earth pressure within in a loose sandy soil is 4% of the wall height (Cl

20、ough and Duncan, 1971). The denser the soil, the less movement required. Applying this </p><p>　　produce movements that large, but over time creep deformation will almost certainly produce movements large en

21、ough to initiate full passive restraint within the backfill.</p><p>　　Vertical loading of the back fill by the immediate fractured roof strata can easily be incorporated into earth pressure theory. The weig

22、ht of the caved material lying on the fill is equivalent to a surcharge load. Over time, bulking of the caved material results in a vertical load equal to the overburden pressure. </p><p>　　Friction between

23、the pillar and fill will have an important effect on the magnitude of the passive pressure applied by the fill. It is expected that the friction between a spalling coal pillar and granular fill material will be quite hig

24、h. However, frictional effects can be accounted for in earth pressure theory. </p><p>　　4 Usefulness of backfilled pillar design using earth pressure theory</p><p>　　The incorporation of Rankine

25、’s method or Log-spiral analysis into standard pillar design has its limitations. In terms of civil engineering applications the functionality Of each of those methods has been verified through experience and each is use

26、d in the design of structures. Since no precedent exists for earth pressure theory being applied to the design of backfilled pillars the usefulness of the approach cannot be corroborated. Furthermore, the Self-Advancing

27、Miner technology is not currentl</p><p>　　The purpose of devising a method of backfilled pillar design using earth pressure theory is to see what conditions may be necessary for backfilling to be practical o

28、r economical. Figure 7 is a plot of recovery rate versus mining depth based on the panel dimensions and pillar widths of Figure 6. This type of plot can be developed for any set of the following conditions:</p>&l

29、t;p>　　1. Post-peak strength of the coal pillar</p><p>　　2. Friction angle of coal</p><p>　　3. Backfill density</p><p>　　4. Friction angle of backfill</p><p>　　5. Coh

30、esion of backfill</p><p>　　6. Magnitude of roof loading</p><p>　　7. Mining dimensions (cut width, length, and seam height).</p><p>　　Thus the importance of any variable can be deter

31、mined in terms of stability and overall recovery, and a concept of what type of backfill may be necessary to achieve a certain rate of recovery can be formulated. In turn, a more detailed economic analysis can be carried

32、 out in terms of the cost of backfilling required to produce an additional ton of coal (Hume and Searle, 1998; Donovan, 1997; Donovan and Karfakis, 2001).</p><p>　　5 Conclusion</p><p>　　There is

33、 little doubt that backfill has the ability to provide support to surroundingpillars. However, quantifying the magnitude of that support has proven to be quite difficult. Earth pressure theory, commonly used in the desig

34、n of civil engineering structures, may provide a preliminary toolfor estimating the amount of support that backfill can provide. The additional strength that backfill provides to surrounding pillars is imparted as a hori

35、zontal pressure along the sides of the pillars. Thi</p><p>　　The extent of roof caving, and subsequent surcharge loading of the backfill, is the most important factor in terms of the magnitude of lateral su

36、pport provided by the backfill. pillar sizes decreaseand recovery increases. However, the fracturing of the immediate roof, and its time-dependency, is reliant upon local geologic and mining conditions. Thus it is diffic

37、ult to predict and quantify the extent of roof caving. The proposed method of backfilled pillar design based on earth pressure theory w</p><p>　　The passive resistance provided by the backfill, and determine

38、d using earth pressure theory, can readily be incorporated into standard pillar design. Typical pillar design is based on ultimate strength, which asserts that a pillar will fail when the load on the pillar exceeds the p

39、illar’s strength. Since a confining pressure acts to increase a pillar’s strength, a relationship between the original pillar strength, confining pressure, and increased strength is necessary to incorporate earth press&l

40、t;/p><p><b>　　.中文譯文</b></p><p>　　土壓力理論在薄煤層回填支柱設計中的應用</p><p><b>　　1導言</b></p><p>　　設計出的SAM技術已經能從小于90厘米厚的煤層中提取煤炭。在理論上，這種技術能提取的全部高度的煤層，同時能盡量減少廢石，并利用遙控

41、操作，使能采煤機推進到一百八十米（六百英尺）的煤層中去。然而，煤層太薄以至于采煤的回收率相當低，并且煤的開采會隨著煤層深度的增加而迅速的減少。為了增加薄煤層礦井的回收率，在保證支柱的設計安全下，必須使支護尺寸盡可能的小。回填在可以增加煤的開采量的同時也提供必要的支護來，從而保持了地下開采運作的完整性。</p><p>　　地下回填已經在煤礦的開采和回填（托馬斯，1979年）中得到了應用?；靥畈牧媳粦玫降叵绿峁┎?/p>

42、在為開采提供工作平臺和有限的支護，從而減少了其中有可能被大規(guī)模移動和支護坍塌而填補了的露天場地空間,（巴瑞特等人，1978年）。回填阻止了由于煤炭開采而留下的空間的坍塌（艾吉森等人，1973年）。因此，在地下的開放空間安置支護往往可以防止剝落的圍巖進入到采空的區(qū)間，所以要增加支護的有效強度和承載能力。這種類型的支護機制不僅提供支柱和墻壁，還防止了頂煤和頂板下落，并盡量的減少了地表沉陷、提高支護的回彈能力（科特斯,1981年）。</

43、p><p>　　雖然回填的支護能力是人所共知的，但它仍然難以量化。廣旭和茂元等人已經提出了回填支護判斷的模型和方程（蔡，1983年；廣旭和茂元，1983年）, 已經使用模擬實驗室對支柱-回填系統(tǒng)進行了設置,這是用來研究支護支撐與實際支護模型之間的關系。但是在一般情況下，這些模型和實驗的檢測,都依賴于本地的經驗以及回填支護、材料性能和幾何特性之間的關系。因為SAM技術仍然是在一個發(fā)展的階段,所以需要一個簡單而可靠的估算

44、方法來評價回填支護的等級,這種方法是基于現(xiàn)有的知識之上的。有建議說古典土壓力理論可以用來估算作用于支護上的側向土壓力。支護對周圍支柱和拱頂的變形預期的效果已經分析出來了。支護的作用已經納入到了支柱設計中，因次新的支柱的寬度可以得到計算，同時煤的回收產量也可以確定了。</p><p><b>　　2稀薄煤礦</b></p><p>　　使用SAM技術，稀薄煤層被稱作為地

45、下露天礦的未開采工作面。圖1描述了由于煤層運輸和削減而形成的幾何平面層。這種支護系統(tǒng)是由于煤層開采而留下的。</p><p>　　使用SAM技術在大約60度的角切開和剪切是可能的，這樣可以減少采礦設備的轉動半徑，同時這又不會影響柱子尺寸的設計。 每個采區(qū)的長度是1200米（1000ft）。每個采區(qū)的寬度隨深度變化而變化，這是為了能夠容納通過每個采區(qū)中心的分隔柱子支護。然而，采區(qū)的寬度將至少大于兩倍的SAM進程所需

46、的距離，在這種情況下至少需要300米(1000ft)。 在采區(qū)開采的過程中，還有分隔柱和一系列的支護體系留了下來。 在采區(qū)開采結束后，大量的分隔柱子也被留了下來從而維護了巷道兩邊的安全。 </p><p>　　圖2是一個煤層開采的斷面圖。這種形式使我們可以同地下露天礦未開采工作面做個比較；煤層通過采區(qū)的中心部位，以及每一次開采上方和下方都留下了余煤。開采寬度是3米(10ft)，并且裁減高度與煤層高度是等效的(少于

47、90厘米(36in))。在無效采空區(qū)，SAM每一次開采和支護的退出，要么使用液壓，要么使用氣動。</p><p><b>　　3土壓力理論的應用</b></p><p>　　前面部分所講的應用土力學來量化回填支護體系的思想并不是前所未有的理論。而應用土壓力理論來解釋支護行為的機理是被廣泛接受的。不過，在地下煤礦中，一般認為應用土壓力的理論和觀念不足以量化支護的等級。由

48、于對于荷載從圍巖向支護摩擦影響轉移認識的程度有限，因此使得土壓力理論在回填支護中的使用變得困難（托馬斯，1979年）。</p><p>　　在薄煤層礦井中，由于支柱設計的失敗，使得SAM的應用變得困難，以至于會出現(xiàn)抵抗支護的被動變形。在土木工程擋土墻設計中已經表明，在松散的沙質土壤中，變形所要達到的最大被動土壓力是該墻的高度的百分之四（可盧斯和鄧肯，1971年）。土壤越密，所需的變形也就越小。運用這一理論，薄煤層

49、煤礦在松散的回填沙土中，高度為九十厘米的支柱，要達到最大被動土壓力，至少必須要有3.6厘米的側向變形。最初階段的支護的失穩(wěn)變形，可能不會產生大的位移，但隨著時間的推移蠕變變形肯定會大的產生運動，大到足以引發(fā)回填支護的抵制。 </p><p>　　應用土壓力理論，對于頂板巖層的瞬間裂隙所引起回填材料產生的垂直載荷可以很容易解釋。由于材料的塌陷作用在支護上的的重量相當于增加了附加荷

50、載。隨著時間的推移，材料膨脹的塌陷，結果相當于產生了垂直荷載。 支柱之間的摩擦，對適用于回填的被動土壓力等級產生重要影響。據推測，剝落煤柱和顆粒填料之間的摩擦相當大。不過，應用土壓力理論可以解釋的摩擦影響。</p><p>　　4使用土壓力理論設計回填支護的優(yōu)越性</p><p>　　由朗肯和勞格斯銳兩者結合的支柱設計標準有其局限性。在土木工程中,每一種理論方法的應用都通過實踐經驗得到了驗

51、證，同時也應用到了結構設計當中去。先前由于在回填支護的設計中，沒有應用土壓力理論，因此這種理論的有用性沒有得到很好的驗證。此外，目前SAM技術還未得到使用，也沒有應用類似的方式從薄煤層中提取煤礦。</p><p>　　在支護回填的設計中使用土壓力理論的目的是為了證明回填支護在什么樣的條件是實際可行的、并且是經濟的。圖7是基于圖6的煤層尺寸規(guī)模和支柱寬度之上的相對煤層深度的回收率。這種類型可以在以下的任何條件下得以

52、發(fā)展：</p><p>　　(1)、煤柱的峰后強度；</p><p><b>　　(2)、煤摩擦角；</b></p><p><b>　　(3)、回填密度；</b></p><p>　　(4)、回填的摩擦角；</p><p>　　(5)、回填的凝聚力；</p>

53、<p>　　(6)、屋面負荷規(guī)模；</p><p>　　(7)、采礦尺寸； </p><p>　　因此，可以應用于穩(wěn)定性和回收率的任何方法的都可以應用。在反過來，關于回填成本的控制，需要更詳細的經濟分析，從而得到開采到更多的煤。</p><p><b>　　5結論</b></p><p>　　因此，毫無疑問，回

54、填給周邊支柱提供了支撐，不過據證明，量化支撐的等級是相當困難。土壓力理論，通常用在土木工程結構的設計中，可以作為初步評價回填所提供支撐能力的分析方法。回填提供給周邊支柱的附加力可以看作是沿支柱兩過的橫向壓力。填充物對于支護橫向變形的作用類似與地下連續(xù)墻結構。朗肯和勞格斯諾確定被動土壓力系數的方法可以用來確定的回填支護的規(guī)模。</p><p>　　冒頂的程度，及隨后的回填附加荷載，是回填所提供的橫向支撐等級確定的最

55、重要因素。支柱大小支護尺寸減小，回收的就增加然而，拱頂的壓裂以及其時間依賴都是建立在當地的地質和采礦條件下的。因此，這是很難預測和量化冒頂的范圍。基于土壓力理論的回填支護的設計仍然有其局限性，直到更嚴格的確定拱頂冒頂方法的出現(xiàn)，它確定了在豎向荷載作用下其規(guī)模。</p><p>　　回填所提供的被動阻力，以及土壓力理論的應用，可以被納入支柱設計的標準中去?；跇O限強度理論的典型支柱設計表明，當負荷對支柱的力量超過支