陳四樓礦2.4Mta新井設(shè)計(jì)【含CAD圖紙+文檔】,含CAD圖紙+文檔,陳四樓礦,mta,設(shè)計(jì),cad,圖紙,文檔 深部礦井巷道支護(hù)技術(shù) 摘要：隨著對(duì)能源需求量的增加和開(kāi)采強(qiáng)度的不斷加大，淺部資源日益減少，國(guó)內(nèi)外礦山都相繼進(jìn)入深部資源開(kāi)采狀態(tài)。我國(guó)煤礦開(kāi)采深度以每年8～12 m的速度增加，未來(lái)10a我國(guó)煤礦深部開(kāi)采的問(wèn)題將越來(lái)越突出。安徽、山東、河南等煤田將建設(shè)一大批新礦井，這些礦井穿越的不穩(wěn)定表土層厚達(dá)400～700 m，巷道位于地下650～1000 m。深部巖體由于受到高地應(yīng)力、特別是側(cè)向高應(yīng)力的作用，.使其具有不同于淺部巖石的特征。深部高應(yīng)力巖巷的巖石強(qiáng)度明顯增加，巖體處于高壓縮變形或破壞極限狀態(tài)，爆破對(duì)圍巖產(chǎn)生的破壞和擾動(dòng)范圍加大，甚至?xí)饚r爆災(zāi)害。本文討論了埋深大于800m的深部礦井巷道及其支護(hù)技術(shù)存在的主要問(wèn)題，并對(duì)影響巷道穩(wěn)定的主要因素進(jìn)行了分析，提出了深部礦井巷道的支護(hù)技術(shù)，并結(jié)合一些礦井的現(xiàn)場(chǎng)實(shí)踐結(jié)果，對(duì)巷道支護(hù)技術(shù)進(jìn)行了總結(jié)，對(duì)于類似地質(zhì)條件下巷道支護(hù)具有一定的借鑒價(jià)值。、 關(guān)鍵詞：深井巷道支護(hù)；穩(wěn)定因素；錨桿支護(hù)技術(shù)；監(jiān)測(cè) 1引言 由于今年來(lái)煤炭需求的不斷增加，各個(gè)礦業(yè)集團(tuán)都在一定程度上加大了礦井的生產(chǎn)能力，加之中東部主要產(chǎn)煤大省，例如山東、安徽、河北、江蘇徐州等的煤炭?jī)?chǔ)量正急劇減少，在這樣的形勢(shì)下，中東部礦井逐步加深了開(kāi)采深度，埋深大于800m的礦井也已越來(lái)越多。在此背景下，隨著采深的不斷加大，深井所帶來(lái)的巷道支護(hù)問(wèn)題的特殊性也越來(lái)越受到重視。目前深井巷道存在的主要問(wèn)題是支護(hù)穩(wěn)定性差、高應(yīng)力、支護(hù)困難，這與礦井深部的巖性和埋深息息相關(guān)。有的礦井埋藏雖然不大，但由于巖性松軟破碎或者膨脹性較為突出，巷道的穩(wěn)定性同樣較差，破壞嚴(yán)重。在同樣巖層條件下，巷道埋深越大巷道越難以穩(wěn)定，支護(hù)也就越來(lái)越困難，破壞也就越嚴(yán)重。如何解決深井巷道支護(hù)的難題，提出一些實(shí)際可行的支護(hù)方式對(duì)于礦井的建設(shè)和安全生產(chǎn)具有重要又迫切的意義。 2深井巷道的礦壓規(guī)律與特點(diǎn) 2.1深井巷道概念 目前國(guó)內(nèi)井工開(kāi)采的煤炭70﹪的產(chǎn)量來(lái)自埋深400m以下的地層中，而巷道的穩(wěn)定性由礦井埋深和巖性兩個(gè)主要因素決定。一般認(rèn)為開(kāi)采深度大于800m的礦井為深井。隨著開(kāi)采深度的增加，巷道礦山壓力也在增加，基本趨勢(shì)如圖1所示 深井巷道存在的主要問(wèn)題包括以下幾點(diǎn)： ⑴ 原巖應(yīng)力大 原巖應(yīng)力與開(kāi)采深度呈線性關(guān)系，深度越深，原巖應(yīng)力越大。同時(shí)，圍巖移近率隨采深的加大也和應(yīng)增大。 ⑵ 構(gòu)造應(yīng)力顯現(xiàn)加劇 構(gòu)造應(yīng)力是由于地殼構(gòu)造運(yùn)動(dòng)在巖體中引起的應(yīng)力.對(duì)于深部巷道，構(gòu)造水平應(yīng)力一般均大于自重應(yīng)力。在構(gòu)造應(yīng)力集中帶，由于構(gòu)造應(yīng)力的作用，薄層頁(yè)巖頂板一般沿層面滑移，厚層砂巖頂板則以小角度或小斷層產(chǎn)生剪切，從而失穩(wěn)冒落；在高水平應(yīng)力作用下，巷道首先從支護(hù)弱面即直接底板破壞，導(dǎo)致底鼓；而兩幫產(chǎn)生很大的拉應(yīng)力，導(dǎo)致兩幫破裂、鼓出和塌落，兩幫比頂板破壞深度更大，從而引起頂板巖層破壞進(jìn)一步發(fā)展。 水平應(yīng)力大小及方向變化很大，較難預(yù)側(cè)和理論計(jì)算，所以實(shí)測(cè)地應(yīng)力對(duì)深部巷道支護(hù)設(shè)計(jì)有著重要價(jià)值。 ⑶ 巖體強(qiáng)度降低 隨著礦井開(kāi)采深度的加大，巖體強(qiáng)度明顯降低。由于采深增加，巷道周邊的集中應(yīng)力超過(guò)了圍巖的自身強(qiáng)度，致使圍巖移近率相對(duì)增加，巷道周邊塑性區(qū)范圍擴(kuò)大。在塑性區(qū)范圍內(nèi)，巖石內(nèi)聚力與內(nèi)摩擦角迅速下降，致使巖體狀態(tài)惡化。 ⑷ 變形呈軟巖特性 由于深部巷道圍巖應(yīng)力大，圍巖強(qiáng)度降低，圍巖孔隙率增大，加上地質(zhì)構(gòu)造發(fā)育的影響，導(dǎo)致巷道變形呈軟巖特性。 ⑸ 頂板離層嚴(yán)重 層理、節(jié)理或裂隙發(fā)育的頂板，在強(qiáng)自重應(yīng)力作用下，特別是下軟上硬頂板，深部比淺部離層更為嚴(yán)重，且遇水呈片狀破碎。 ⑹ 沖擊地壓發(fā)生頻率及強(qiáng)度增大 礦井采深越大，自重應(yīng)力越大。在堅(jiān)硬頂板條件下。巷道圍巖或煤體積聚的彈性能也增大，特別在構(gòu)造應(yīng)力集中區(qū)，當(dāng)支架-圍巖作用平衡體受到諸如放炮等因素誘發(fā)而失穩(wěn)時(shí)，更易發(fā)生沖擊地壓。例如徐州礦區(qū)自1991年7月10日在權(quán)臺(tái)煤礦發(fā)生首例沖擊地壓以來(lái)，已先后在三河尖、張集、旗山、張小樓等礦(井)發(fā)生20多次沖擊地壓。 2.2 深井礦壓規(guī)律 1）地應(yīng)力概念 豎向垂直壓力主要來(lái)自于上覆巖層自重壓力P。即： P=kγH 式中： P——上覆巖層壓力，t/m2； γ——巖層容重，t/m3； H——深度，m； k——與巖層性質(zhì)有關(guān)系數(shù)。 從上式可以看出，在同類圍巖條件下，巷道埋深越大，地應(yīng)力相對(duì)越大。 2 ）主應(yīng)力方向?qū)ο锏婪€(wěn)定的影響 原巖地層中的任一點(diǎn)的盈利處于平衡狀態(tài)，巷道開(kāi)挖后，由于褶曲、斷層、火成巖侵入等地質(zhì)作用，圍巖盈利重新分布，巷道周圍應(yīng)力不均等，造成巷道不同形式的破壞。應(yīng)力方向分為垂直應(yīng)力和水平應(yīng)力，因此主應(yīng)力方向與巷道方向的關(guān)系影響其穩(wěn)定性。見(jiàn)圖2。 (1)當(dāng)巷道軸向與最大水平主應(yīng)力方向平行時(shí)，受水平應(yīng)力影響最小，對(duì)巷道的穩(wěn)定最為有利。 (2)當(dāng)巷道軸向與最大水平主應(yīng)力方向垂直時(shí)，受水平應(yīng)力影響最犬，對(duì)巷道的穩(wěn)定最為不利。 (3)最大水平主應(yīng)力方向與斜交的巷道，巷道一側(cè)出現(xiàn)應(yīng)力集中而另一側(cè)出現(xiàn)應(yīng)力釋放，因而巷道的變形破壞會(huì)偏向某一側(cè)。 ⑷水平應(yīng)力大于垂直應(yīng)力，容易產(chǎn)生底臌，巷道不穩(wěn)定。 3開(kāi)采深度與巷道圍巖的變形關(guān)系 3.1中國(guó)的研究 開(kāi)采深度對(duì)巷道圍巖的影響十分復(fù)雜，除與巷道的圍巖性質(zhì)密切相關(guān)外，如受采動(dòng)影響的巷道，則與護(hù)巷方式和周圍采動(dòng)狀況等也有密切關(guān)系。根據(jù)我國(guó)的研究成果，可得開(kāi)采深度與巷道維護(hù)之間的一般關(guān)系如下: (1)巖體的原巖應(yīng)力即上覆巖層重量，是在巖體內(nèi)掘巷時(shí)巷道圍巖出現(xiàn)應(yīng)力集中和周邊位移的基本原因。因此，隨開(kāi)采深度增加，必然會(huì)引起巷道圍巖變形和維護(hù)費(fèi)的顯著增長(zhǎng)。 (2)巷道的圍巖變形量或維護(hù)費(fèi)用隨采深的增加近似的呈線性關(guān)系增長(zhǎng)。 (3)巷道圍巖變形和維護(hù)費(fèi)用隨開(kāi)采深度的增長(zhǎng)的幅度，與巷道圍巖性質(zhì)有密切關(guān)系，圍巖愈松軟，巷道變形隨采深增長(zhǎng)愈快，反之，圍巖愈穩(wěn)定，巷道變形隨采深增長(zhǎng)愈慢。 (4)巷道圍巖變形和維護(hù)費(fèi)用的增長(zhǎng)率還與巷道所處位置及護(hù)巷方式有關(guān)，開(kāi)采深度對(duì)卸壓內(nèi)的巷道影響最小，對(duì)位于煤體內(nèi)巷道及位于煤體-煤柱內(nèi)巷道的影響次之，對(duì)兩側(cè)均已采空的巷道影響最大。 3.2前蘇聯(lián)的研究 前蘇聯(lián)對(duì)礦井開(kāi)采深度與巷道穩(wěn)定性的關(guān)系進(jìn)行過(guò)大量研究，認(rèn)為深部巷道礦壓顯現(xiàn)的一個(gè)主要特點(diǎn)是在巷道掘進(jìn)時(shí)就呈現(xiàn)圍巖強(qiáng)烈變形，且在掘進(jìn)后圍巖長(zhǎng)期流變，使巷道支架承受很大壓力。淺部開(kāi)采時(shí)表現(xiàn)不明顯的掘巷引起的圍巖變形，在深部開(kāi)采時(shí)顯現(xiàn)十分強(qiáng)烈。根據(jù)在頓巴斯礦區(qū)進(jìn)行的大量巷道礦壓觀測(cè)，提出了深部巷道掘進(jìn)初期圍巖移近量的計(jì)算公式為: 式中: 、——頂板、兩幫在掘進(jìn)后t時(shí)間內(nèi)的位移量，cm； t——時(shí)間，d; 、—頂板,兩幫作用在支架上的壓力，kN/㎡ ； γ——巖石容重，kN/m'； H——巷道所處的深度，m； R—巖石單軸抗壓強(qiáng)度，kPa； Ro—尋求常數(shù)時(shí)引人的單軸抗壓強(qiáng)度，3000kPa； b—巷道所處的深度，cm； h—巷道高度，cm； 由此可以看出隨著開(kāi)采深度的增加，維護(hù)時(shí)間的增長(zhǎng)，巷道變形將逐漸增加，維護(hù)也越困難。 4 影響巷道穩(wěn)定的因素 4.1 穩(wěn)定性系數(shù) 影響巷道穩(wěn)定的因素有很多，研究認(rèn)為，埋深600～1200m的巷道圍巖穩(wěn)定性指數(shù)表示，圍巖自穩(wěn)指數(shù)小于1，指數(shù)越小巷道越穩(wěn)定。 S=γh/R S——圍巖穩(wěn)定性系數(shù)； R——巖石單項(xiàng)抗壓強(qiáng)度； 4.2 影響因素分析 1） 巖石力學(xué)性質(zhì) 包括強(qiáng)度、孔隙度、吸水率、膨脹性、崩解性等，但主要的是堅(jiān)固性系數(shù)f，即R值。 2） 圍巖結(jié)構(gòu) 巷道周圍巖體稱為圍巖，圍巖結(jié)構(gòu)是非均質(zhì)性的，圍巖的層理、節(jié)理、裂隙密度、膠結(jié)程度等均影響巷道穩(wěn)定。 3） 圍巖物相 指巖體中的礦物組成，如含蒙脫石、伊利石、高嶺石等，粘土礦物成分，含量過(guò)高，遇到水會(huì)發(fā)生膨脹、蠕變、流變。 4） 地質(zhì)構(gòu)造應(yīng)力 重點(diǎn)是位于向斜、背斜軸部、與斷層走向一致或過(guò)斷層的巷道。 5） 地下水與水溫 地下水使層理、節(jié)理、裂隙發(fā)育的巖體滑動(dòng)、松散，動(dòng)壓水增加了壓力；膨脹性巖石遇水加固巷道變形。 低溫過(guò)高使巖石軟化，工作環(huán)境差，對(duì)巷道穩(wěn)定不利。 6） 巷道布置與開(kāi)挖順序 兩條巷道平行，其間隔巖柱太小，巷道難穩(wěn)定;特別當(dāng)巖柱小于巷道開(kāi)挖寬度的3倍時(shí)，產(chǎn)生應(yīng)力疊加嚴(yán)重，先開(kāi)挖巷道受后開(kāi)挖巷道再次應(yīng)力分配達(dá)到峰值時(shí)，更易使巷道變形破壞。 7）巷道斷面尺寸和形狀 巷道開(kāi)挖表面積與巷道穩(wěn)定程度成反比，其形狀越接近圓形越有利于穩(wěn)定。 8）支護(hù)材料與結(jié)構(gòu)形式 主要是支護(hù)材料的強(qiáng)度、剛度和彈塑性。結(jié)構(gòu)形式主要指改變圍巖應(yīng)力狀態(tài)的方式，如錨桿、錨索起懸吊、擠壓、加固作用，網(wǎng)噴起表面封閉和調(diào)節(jié)應(yīng)力集中作用;注漿則將松散破碎巖體粘結(jié)成整體，起固結(jié)強(qiáng)化并改善圍巖應(yīng)力狀態(tài)等主動(dòng)支護(hù)作用。 9）支護(hù)參數(shù) 支護(hù)參數(shù)主要指材料的強(qiáng)度、規(guī)格、型號(hào)，結(jié)構(gòu)原理、方式，支護(hù)結(jié)構(gòu)在圍巖中的布置密度、形式等。如錨桿材料、錨固形式，直徑、長(zhǎng)度、錨固力、預(yù)緊力。錨桿布置方式、間排距等。重點(diǎn)是支護(hù)強(qiáng)度大于外力臨界值。 10）施工工藝與質(zhì)量 開(kāi)挖方式對(duì)圍巖擾動(dòng)程度和范圍不同，所以光面爆破，降低裝藥量是保護(hù)圍巖的有效方法;支護(hù)順序和時(shí)間;支護(hù)設(shè)備及工藝過(guò)程;施工操作執(zhí)行力;檢驗(yàn)評(píng)價(jià)方法;質(zhì)量管理及控制體系等。前五條是客觀因素，后五條是主觀因素。 5深部巷道圍巖變形規(guī)律及其支護(hù)對(duì)策 認(rèn)識(shí)深部巷道圍巖變形特征是分析圍巖變形破壞機(jī)理和確定支護(hù)對(duì)策的前提條件。 5.1深部巷道圍巖具有軟巖的力學(xué)特征 深部巷道圍巖常受到原巖應(yīng)力和巷道工程力的影響，在深部高應(yīng)力環(huán)境中，當(dāng)圍壓較高時(shí)，巖體尚具有較高的強(qiáng)度和模量(彈性模量或變形模量)，當(dāng)圍壓較低時(shí)，工程巖體則表現(xiàn)出“軟巖”特征;因此巷道圍巖具有軟巖相對(duì)性的實(shí)質(zhì)。當(dāng)巷道工程力一定時(shí)，不同的巖體，強(qiáng)度高于工程力水平的大多表現(xiàn)為硬巖的力學(xué)特性，強(qiáng)度低于工程力水平的則可能表現(xiàn)為軟巖的力學(xué)特性;而對(duì)同種巖石，在較低工程力的作用下，則表現(xiàn)為硬巖的小變形特性，在較高工程力的作用下則可能表現(xiàn)為軟巖的大變形特性。 5.2 巷道圍巖穩(wěn)定性分類 5.2.1按圍巖松動(dòng)圈的分類方法 圍巖松動(dòng)圈是指巷道掘進(jìn)后，用國(guó)產(chǎn)聲波儀測(cè)定圍巖聲波降低范圍的平均值。中國(guó)礦業(yè)大學(xué)建工學(xué)院測(cè)定的圍巖松動(dòng)圈的范圍，進(jìn)行圍巖穩(wěn)定性分類，見(jiàn)表5-2-1. 表5-2-1 巷道圍巖穩(wěn)定性（松動(dòng)圈）分類 圍巖類別 分類名稱 圍巖松動(dòng)圈/mm 小松動(dòng)圈 Ⅰ 穩(wěn)定圍巖 0~40 中松動(dòng)圈 Ⅱ 較穩(wěn)定圍巖 40~100 Ⅲ 一般圍巖 100~150 大松動(dòng)圈 Ⅳ 一般不穩(wěn)定圍巖（軟巖） 150~200 Ⅴ 不穩(wěn)定圍巖（較軟圍巖） 200~300 Ⅵ 極不穩(wěn)定圍巖（極軟圍巖） >300 5.2.2按圍巖變形量的分類方法 圍巖表形量是巷道開(kāi)挖后受多種因素影響的綜合結(jié)果，是圍巖穩(wěn)定性分類的多因素單一定量指標(biāo)，煤炭科學(xué)研究總院北京建井所據(jù)此指定的巷道圍巖分類見(jiàn)表5-2-2。 表5-2-2 按圍巖變形量制定的圍巖分類 圍巖類別 開(kāi)挖后圍巖變形量/mm Ⅰ <5 Ⅱ 6~10 Ⅲ 11~50 Ⅳ 50~200 Ⅴ >200 深部巷道原巖應(yīng)力大，圍巖具有軟巖的大變形特征，決定了巷道收斂具有變形量大的特點(diǎn)。據(jù)測(cè)量數(shù)據(jù)，研究區(qū)各巷道收斂變形量均很大，一般為數(shù)十毫米到數(shù)百毫米，最大可達(dá)1.0m以上，嚴(yán)重的可封堵整個(gè)巷道。如唐山礦業(yè)分公司T2154(5煤層)運(yùn)輸巷道其巷道累計(jì)水平變形量184.3 mm，垂直變形量62.6mm，底鼓變形量85.9 mm(圖4)。巷道變形以水平收斂為主，其表現(xiàn)形式有側(cè)幫內(nèi)移，頂板垮落和底鼓。在未封底和未設(shè)置抑拱的某些巷道，因兩幫和拱頂進(jìn)行了支護(hù)，阻礙了相應(yīng)部位圍巖的繼續(xù)變形和圍巖的進(jìn)一步調(diào)整，底板就成為最薄弱環(huán)節(jié)，于是應(yīng)力釋放和巖體擴(kuò)容變形就在底板發(fā)生，從而普遍產(chǎn)生底鼓。 深部巷道圍巖變形的另一個(gè)特征是明顯的時(shí)效性。在地下巷道和采場(chǎng)工程中表現(xiàn)出來(lái)的力學(xué)現(xiàn)象，包括地壓、變形、破壞等幾乎都與時(shí)間有關(guān)。嚴(yán)格地講，以往應(yīng)用彈性力學(xué)和彈塑性力學(xué)求得的巷道變形和應(yīng)力都是瞬時(shí)發(fā)生的，既量測(cè)不到也無(wú)法阻止。圍巖變形可分為劇烈變形、緩慢變形和穩(wěn)定變形3個(gè)階段。圍巖收斂變形是否穩(wěn)定還取決于支護(hù)結(jié)構(gòu)的剛度和強(qiáng)度。據(jù)破碎銅室的監(jiān)測(cè)資料，開(kāi)挖6個(gè)月變形速度無(wú)明顯降低，一般維持在0.45～2.15 mm/d，且大部分地段變形有所加快。而且由于這種流變產(chǎn)生圍巖的變形壓力一旦使支護(hù)失效，圍巖再次惡化并強(qiáng)烈變形,如此反復(fù)，這就是某些硐室出現(xiàn)返修而未能有效阻止圍巖變形和破壞的根本原因。 5. 3深部圍巖巷道載荷特征 現(xiàn)代支護(hù)理論認(rèn)為，巷道圍巖支護(hù)應(yīng)充分發(fā)揮圍巖的自承作用。圍巖本身既是載荷的來(lái)源又是支護(hù)結(jié)構(gòu)的主體。圍巖的自承力是由巷道的斷面形態(tài)和圍巖本身的物理力學(xué)性質(zhì)決定的。根據(jù)松動(dòng)圈支護(hù)理論(圖5)，圍巖的狀態(tài)特征決定著支護(hù)能夠起的作用，彈塑性狀態(tài)特征的圍巖能夠自穩(wěn)，多數(shù)不需要支護(hù);只有當(dāng)圍巖進(jìn)人到破碎狀態(tài)之后才產(chǎn)生了支護(hù)問(wèn)題。凡裸體巷道，圍巖松動(dòng)圈都接近于零，此時(shí)的彈塑性變形依然存在，但它不需要支護(hù)；松動(dòng)圈越大收斂變形越大，支護(hù)越困難；巷道收斂與松動(dòng)圈形成在時(shí)間上是一致的。因此，圍巖松動(dòng)圈所產(chǎn)生的碎脹變形是支護(hù)控制的主要對(duì)象(未考慮水等的因素)，同時(shí)應(yīng)該在松動(dòng)圈形成時(shí)，及時(shí)采取支護(hù)措施，獲得最佳支護(hù)效果，這就是深部巷道圍巖對(duì)控制時(shí)間的要求。 6深井巷道支護(hù)技術(shù) 6. 1深井巷道變形規(guī)律 圖3為魯西南地區(qū)埋深800～1100m巷道圍巖一般變形規(guī)律。巷道支護(hù)后變形量一般在30～70mm時(shí)出現(xiàn)開(kāi)裂、爆皮現(xiàn)象，但還未冒落時(shí)要進(jìn)行二次加固;要及時(shí)進(jìn)行位移觀測(cè)。 6. 2深井巷道支護(hù) 6.2.1深井巷道支護(hù)原理 根據(jù)上述規(guī)律，深井巷道支護(hù)應(yīng)是卸固原理:“支、卸、固”方式，即擴(kuò)大斷面待卸壓后及時(shí)二次加固。 支:第一次用錨、網(wǎng)、噴、支護(hù)后； 卸:巷道雖有變形、開(kāi)裂、剝皮卸壓現(xiàn)象，但尚未造成圍巖脫離原巖體、片幫、冒頂； 固:隨后進(jìn)行錨注加固。 6.2.2支護(hù)結(jié)構(gòu)形式 適應(yīng)深井高應(yīng)力巷道的支護(hù)形式有:“支、卸、固法”、“支修法”、“強(qiáng)抗法”、“超前加固法”、“應(yīng)力轉(zhuǎn)移法”等，但較為經(jīng)濟(jì)、實(shí)用、有效的方法是“支、卸、固法”。其它方法工序復(fù)雜，成本較高。合理支護(hù)結(jié)構(gòu)形式的核心是對(duì)適應(yīng)地壓規(guī)律和圍巖的性質(zhì)。 6.2.3 支護(hù)方法及對(duì)策 ⑴ 正確選擇巷道層位、位置巷道的布置應(yīng)避開(kāi)煤柱集中應(yīng)力、構(gòu)造集中應(yīng)力、采動(dòng)應(yīng)力的影響，選擇在巖性較為穩(wěn)定的巖石中。深部采區(qū)主要準(zhǔn)備巷道應(yīng)以巖巷為主或至少布置一條巖巷。隨著深度的增加，回采工作面推進(jìn)后煤體塑性區(qū)增加，致使區(qū)段煤柱留設(shè)寬度隨之增加，為保證采區(qū)回收率，減少巷道維護(hù)，工作面回風(fēng)(運(yùn)輸)平巷宜采用無(wú)煤柱護(hù)巷的形式。 ⑵ 合理選擇巷道施工方位在遇到以壓應(yīng)力為主的褶曲、逆斷層時(shí)，巷道方向盡量與摺曲軸或斷層走向垂直或斜交，在遇到以拉應(yīng)力為主的正斷層時(shí)，巷道方向則與斷層走向一致或斜交，從而達(dá)到減小礦壓顯現(xiàn)的目的。 回采巷道布置的方位應(yīng)使工作面離開(kāi)斷層推進(jìn)，使采區(qū)一翼內(nèi)工作面同向推進(jìn)。避免巷道相向掘進(jìn)和巷道近距離平行布置，減少相交巷道(或避開(kāi)銳 角)，從而減小應(yīng)力集中，減少發(fā)生沖擊地壓的危險(xiǎn)性。 ⑶ 改革巷道支護(hù)形式，達(dá)到最佳支護(hù)效果 針對(duì)深部巷道礦壓顯現(xiàn)特點(diǎn)。要求巷道支護(hù)必項(xiàng)滿足既能加固圍巖又能提供較大的支護(hù)力、具有較大的可縮性和一定的初撐力等要求，根據(jù)圍巖狀況和巷道條件，采用不同的支護(hù)形式。 ① 樹(shù)脂錨桿+梁+網(wǎng)組合支護(hù) 樹(shù)脂錨桿采用樹(shù)脂藥卷作為錨固劑，分端錨、全錨和加長(zhǎng)錨固3種形式，圓鋼或螺紋鋼為桿體，再配以金屬網(wǎng)、梁。使用此種錨桿能有效地提高圍巖的自承能力。此種支護(hù)在綜放大斷面煤巷或切眼中經(jīng)常使用。 ② 錨梁網(wǎng)+錨索聯(lián)合支護(hù)深部 巷道以錨桿支護(hù)配以錨索支護(hù)，可使層狀頂板形成一個(gè)整體的組合梁，同時(shí)也起到懸吊作用，可防止圍巖受拉破壞，并能提高圍巖的整體抗彎強(qiáng)度。此種錨桿常在圍巖不穩(wěn)定、層理發(fā)育、跨度較大的巷道中使用。 ③ 全封閉錨梁網(wǎng)+底梁聯(lián)合支護(hù) 由于深部巷道的變形呈軟巖特性、巷道圍巖破碎圈增大等特點(diǎn)，例如徐州礦務(wù)局龐莊煤礦張小樓并-1025m大巷原采用常規(guī)錨梁網(wǎng)支護(hù)形式，致使巷道尚未投人使用就產(chǎn)生如前所述的較大變形，后采用樹(shù)脂錨桿(端錨)+梁、網(wǎng)+U型鋼底梁的全封閉支護(hù)形式二次施工，其中錨桿長(zhǎng)度由原來(lái)1.8m加長(zhǎng)至2.2m，錨桿直徑由,18mm加大到20 mm，使錨桿錨固力達(dá)6t以上，7d內(nèi)巷道變形速度僅3mm/d，取得了較好的支護(hù)效果。 ④ 圍巖注漿加固+U 型支架聯(lián)合支護(hù) 在深部極破碎頂板條件下，除采用加長(zhǎng)樹(shù)脂錨桿再配以錨索支護(hù)外，張集煤礦-700 m水平西大巷延長(zhǎng)段施工中還采用了圍巖注漿加固技術(shù)。通過(guò)向巷道圍巖中注漿，漿液中摻入ZKD高水速凝材料，將松散的圍巖膠結(jié)成整體，降低圍巖的孔隙率，提高了巷道圍巖的整體性和自身承載能力。進(jìn)而保證了巷道輪廓線按設(shè)計(jì)成形，使圍巖與支架充分接觸，支架均勻承載，發(fā)揮U型支架高承載能力的性能，有效地控制了圍巖變形.實(shí)測(cè)兩幫移近量由注漿前800～1×1000mm減少到注漿后100～200mm，提高了支護(hù)效果。 結(jié)合實(shí)際礦井應(yīng)用，針對(duì)有代表性且應(yīng)用越來(lái)越廣泛的錨桿支護(hù)技術(shù)做詳細(xì)的介紹。 7深井錨桿支護(hù)技術(shù) 7.1 錨桿支護(hù)理論 目前國(guó)內(nèi)礦井對(duì)于深井巷道支護(hù)多采用錨桿支護(hù)技術(shù)。關(guān)于錨桿支護(hù)理論，有以下幾種主流的理論。 ⑴ 懸吊理論 對(duì)于回采巷道經(jīng)常遇到的層狀巖體，當(dāng)巷道開(kāi)挖后，直接頂因彎曲、變形與老頂分離，如果錨桿及時(shí)將直接頂擠壓并懸吊在老頂上，就能減少和限制直接頂?shù)南鲁梁碗x層，以達(dá)到支護(hù)的目的。如圖3-1所示。 巷道淺部圍巖松軟破碎，或者開(kāi)挖巷道后應(yīng)力重新分布，頂板出現(xiàn)破裂區(qū)，這時(shí)錨桿的懸吊作用就將這部分易冒落巖體懸吊在深部未松動(dòng)巖層上。這是懸吊理論的進(jìn)一步發(fā)展，如圖3-2所示。 圖3-1錨桿的懸吊作用 圖3-2頂板錨桿懸吊松動(dòng)破裂巖層 ⑵ 組合梁理論 組合梁理論認(rèn)為：在層狀巖體中開(kāi)挖巷道，當(dāng)頂板在一定范圍內(nèi)不存在堅(jiān)硬穩(wěn)定的巖層時(shí)，錨桿的懸吊作用居次要地位。 如果頂板巖層中存在若干分層，頂板錨桿的作用，一方面是依靠錨桿的錨固力增加各巖層間的摩擦力，防止巖石層面滑動(dòng)，避免各巖層出現(xiàn)離層現(xiàn)象；另一方面，錨桿桿體可增加巖層間的抗剪剛度，阻止巖層間的水平錯(cuò)動(dòng)，從而將巷道頂板錨固范圍內(nèi)的幾個(gè)薄巖層鎖緊成一個(gè)較厚的巖層（組合梁）。這種組合厚巖層在上覆巖層載荷的作用下，其最大彎曲應(yīng)變和應(yīng)力都將大大減少，組合梁的撓度亦減少，梁內(nèi)的最大應(yīng)力、應(yīng)變和梁的撓度也就減少。如圖3-3所示。 圖3-3頂板錨桿組合梁作用 （a）未打錨桿(b)布置頂板錨桿 組合梁理論，是對(duì)錨桿將頂板巖層鎖緊成較厚巖層的解釋。在分析中，將錨桿作用與圍巖的自穩(wěn)作用分開(kāi)，與實(shí)際圍巖的條件的變化，在頂板較破碎、連續(xù)性受到破壞，組合梁就不存在了。 組合梁理論只適合與層狀頂板錨桿支護(hù)設(shè)計(jì)，對(duì)于巷道的幫、底不適用。 ⑶ 組合拱理論 組合拱理論認(rèn)為：在拱形巷道圍巖的破裂區(qū)中安裝預(yù)應(yīng)力錨桿時(shí)，在桿體兩端將形成圓錐形分布的壓應(yīng)力，如果沿巷道周邊布置錨桿群，只要錨桿間足夠小，各錨桿形成的壓應(yīng)力圓錐體將相互交錯(cuò)，就能在巖體中形成一個(gè)均勻的壓縮帶，即承壓拱，這個(gè)承壓拱可以承受其上部破碎巖石施加的徑向載荷。在承壓內(nèi)的巖石徑向及切向均受壓，處于三向應(yīng)力狀態(tài)，其圍巖強(qiáng)度得到提高，支撐能力頁(yè)相應(yīng)加大，如圖3-4所示。因此，錨桿支護(hù)的關(guān)鍵在于獲取較達(dá)的承壓拱厚度和較高的強(qiáng)度。其厚度越大，越有利于圍巖的穩(wěn)定和支承能力的提高。 組合拱理論在一定程度上揭示了錨桿支護(hù)的作用原理，但在分析過(guò)程中沒(méi)有深入考慮圍巖—支護(hù)的相互作用，只是將各支護(hù)結(jié)構(gòu)的最大支護(hù)力簡(jiǎn)單相加，從 圖3-4錨桿的組合拱原理 而得到復(fù)合支護(hù)結(jié)構(gòu)總的最大支護(hù)力，缺乏對(duì)被加固巖體本身力學(xué)行為的進(jìn)一步分析探討，計(jì)算也與實(shí)際情況存在一定差距，一般不能作為準(zhǔn)確的定量設(shè)計(jì)，但可作為錨桿加固設(shè)計(jì)和施工的重要參考。 ⑷ 最大水平應(yīng)力理論 自從八十年代以來(lái), 水平應(yīng)力對(duì)巷道穩(wěn)定性的影響已經(jīng)引起了人們的普遍關(guān)注。澳大利亞W.Gale博士(1987)通過(guò)數(shù)值模擬分析及現(xiàn)場(chǎng)觀測(cè)，得到了水平應(yīng)力對(duì)巷道穩(wěn)定性的最 圖3-5應(yīng)力場(chǎng)效應(yīng) 基本的認(rèn)識(shí)：礦井巖層的水平應(yīng)力通常大于垂直應(yīng)力，水平應(yīng)力具有明顯的方向性，最大水平應(yīng)力一般為最小水平應(yīng)力的1.5～2.5倍。巷道頂?shù)装宓姆€(wěn)定性主要受水平應(yīng)力的影響：巷道軸向與最大主應(yīng)力方向平行時(shí)， 巷道受水平應(yīng)力的影響最?。欢叽怪睍r(shí)，巷道受水平應(yīng)力的影響最大；二者呈一定夾角時(shí)，巷道其中一側(cè)會(huì)出現(xiàn)水平應(yīng)力集中而另一側(cè)應(yīng)力較低，因而頂?shù)装宓淖冃螘?huì)偏向巷道的某一側(cè)。如圖3-5所示。并提出在最大水平地應(yīng)力的作用下, 頂?shù)装鍘r層易于發(fā)生剪切破壞，出現(xiàn)錯(cuò)動(dòng)與松動(dòng)而造成圍巖變形，錨桿的作用即是約束其沿軸向巖層膨脹和垂直于軸向的巖層剪切錯(cuò)動(dòng)，因此要求錨桿必須具有強(qiáng)度大、剛度大、抗剪切阻力大的特點(diǎn)才能起到約束圍巖變形的作用。所以，澳大利亞錨桿支護(hù)特別強(qiáng)調(diào)錨桿高強(qiáng)及全長(zhǎng)膠結(jié)。 ⑸ 圍巖松動(dòng)圈支護(hù)理論 圍巖松動(dòng)圈理論認(rèn)為：(1)地應(yīng)力與圍巖相互作用會(huì)產(chǎn)生圍巖松動(dòng)圈；(2)松動(dòng)圈形成過(guò)程中產(chǎn)生的碎脹力及其所造成的有害變形是巷道支護(hù)的主要對(duì)象，松動(dòng)圈尺寸越大，巷道收斂變形也越大，支護(hù)越困難。(3)依據(jù)松動(dòng)圈的大小采用不同的原理設(shè)計(jì)錨桿支護(hù)。小松動(dòng)圈(0～40 cm)采用噴射混凝土支護(hù)即可；中松動(dòng)圈(40～150 cm)采用懸吊理論設(shè)計(jì)錨桿支護(hù)；大松動(dòng)圈(> 150 cm )采用組合拱原理設(shè)計(jì)錨桿支護(hù)參數(shù)。 由于圍巖松動(dòng)圈是隨著時(shí)間、巷道支護(hù)形式及支護(hù)強(qiáng)度的變化而變化，并且在同一斷面上由于巖性的差異，圍巖松動(dòng)圈的大小也是不一樣的。所以，在復(fù)雜條件下圍巖松動(dòng)圈理論(如煤巷、軟巖巷道)并沒(méi)有得到應(yīng)用。松動(dòng)圈支護(hù)理論對(duì)于錨桿支護(hù)的指導(dǎo)作用主要在于確定普通錨桿(如普通圓鋼錨桿、水泥藥卷錨桿等等)的適用條件和范圍。 ⑹ 減跨理論 在懸吊理論和組合梁理論的基礎(chǔ)上，提出了減跨理論。該理論認(rèn)為：錨桿末端固定在穩(wěn)定巖層內(nèi)，穿過(guò)薄層狀頂板，每根錨桿相當(dāng)于一個(gè)鉸支點(diǎn)，將巷道頂板劃分成小跨，從而使頂板撓度降低。如圖3-6減跨作用原理。 在巷道頂板上安裝錨桿以后，將巷道頂板劃分成多個(gè)小跨，成為多跨連續(xù)梁結(jié)構(gòu)，其冒落拱高度及頂板下沉量均有大幅度的降低，從而使巷道圍巖更加穩(wěn)定。 圖3-6減跨作用原理 ⑺ 圍巖強(qiáng)度強(qiáng)化理論 巷道圍巖強(qiáng)度強(qiáng)化理論揭示了錨桿的作用原理和加固巷道圍巖的實(shí)質(zhì)，并為 合理確定錨桿支護(hù)參數(shù)提供了理論依據(jù)。該理論要點(diǎn)：(1)巷道錨桿支護(hù)實(shí)質(zhì)使錨桿和錨固區(qū)域的巖體相互作用而組成錨固體，形成統(tǒng)一的承載結(jié)構(gòu)；（2）巷道錨桿支護(hù)可以提高錨固提力學(xué)參數(shù)，包括錨固體破壞前和破壞后的力學(xué)參數(shù)（E、C、ф），改善被錨固巖體的力學(xué)性能；（3）巷道圍巖存在破碎區(qū)、塑性區(qū)、彈性區(qū)，錨桿錨固區(qū)巖體的峰值強(qiáng)度、殘余強(qiáng)度均能得到強(qiáng)化；（4）巷道錨桿支護(hù)可以改變威嚴(yán)的應(yīng)力狀態(tài)、增加圍壓，從而提高圍巖的承載能力、改善巷道的支護(hù)狀態(tài)；（5）巷道圍巖錨固體強(qiáng)度提高后，可減少巷道周圍破碎區(qū)、塑性區(qū)的范圍和巷道的表面位移，控制圍巖破碎區(qū)、塑性區(qū)的發(fā)展，從而有利于保持巷道圍巖的穩(wěn)定。 7.2采用大直徑、高強(qiáng)度、大延伸量錨桿 錨桿的強(qiáng)度直接影響其錨固范圍內(nèi)圍巖強(qiáng)度的強(qiáng)化和錨桿對(duì)巷道圍巖的支護(hù)阻力，從而影響錨桿群作用范圍內(nèi)圍巖的承載能力和錨桿的支護(hù)效果。 (1)增加錨桿的桿體直徑和采用高強(qiáng)度鋼筋。我國(guó)以往錨桿的普通圓鋼錨桿的桿體直徑一般為14 mm,16 mm,18 mm，材質(zhì)為，其屈服強(qiáng)度為240 MPa，破斷力均在100kN以下。國(guó)外使用的錨桿桿體屈服強(qiáng)度為400～600MPa，甚至更高，破斷力一般為200～300kN，甚至更大。如美國(guó)高強(qiáng)度螺紋鋼桿體的屈服強(qiáng)度為414～689MPa，拉斷強(qiáng)度為621～862MPa；英國(guó)高強(qiáng)度螺紋鋼桿體的屈服強(qiáng)度為640～720MPa。為了達(dá)到和超過(guò)國(guó)外錨桿桿體材料水平，滿足我國(guó)深井巷道支護(hù)的要求，開(kāi)發(fā)出錨桿專用鋼材配方，其中BHRB500, BHRB600型號(hào)的鋼材可用于生產(chǎn)強(qiáng)力錨桿。這2種鋼材的公稱直徑均為22～25mm，屈服強(qiáng)度分別為500，600MPa,抗拉強(qiáng)度分別為670,800MPa，伸長(zhǎng)率均18%。對(duì)于中Ф22mm的BHRB600型鋼筋，屈服力達(dá)228.1kN，破斷力達(dá)304.1kN。分別是同直徑建筑螺紋鋼的1.79和1.63倍；是同直徑圓鋼的2.50和2.11倍。 (2)錨桿尾部螺紋熱處理或桿體整體調(diào)質(zhì)處理是一種提高錨桿桿體強(qiáng)度而成本較低的方法。 (3)增加錨桿的延伸量。為了改變普通圓鋼錨桿延伸量較小、不能適應(yīng)巷道圍巖較大變形的缺點(diǎn)，為達(dá)到提高錨桿錨尾的拉斷力和充分發(fā)揮桿體材料 的強(qiáng)度性能的目的，中國(guó)礦業(yè)大學(xué)研制了結(jié)構(gòu)簡(jiǎn)單、加工方便的桿體可延伸增強(qiáng)錨桿。該錨桿的材料為含碳、磷、硫較低、延伸率較大的圓鋼，通過(guò)對(duì)錨桿的錨尾進(jìn)行強(qiáng)化熱處理而制成。桿體可延伸錨桿與同直徑、同材質(zhì)的普通圓鋼錨桿相比，其對(duì)巷道圍巖的支護(hù)阻力可提高34%～40%，適應(yīng)圍巖的變形量可增大500%以上。 阻止深部巷道圍巖發(fā)生較大變形既不經(jīng)濟(jì)也不合理。高強(qiáng)度錨桿支護(hù)可提供較大的支護(hù)阻力，控制圍巖塑性區(qū)及破碎區(qū)發(fā)展、降低塑性區(qū)流變速度， 提高支護(hù)阻力可以大大減小圍巖變形；大延伸量錨桿支護(hù)允許圍巖有一定變形，降低圍巖應(yīng)力、減少錨桿載荷防止錨桿破斷，改善巷道維護(hù)狀況。因此，必需研制大直徑、高強(qiáng)度、具有較高延伸率的錨桿來(lái)解決深部巷道支護(hù)問(wèn)題，以滿足生產(chǎn)的要求。 7.3增大錨桿預(yù)緊力 錨桿的作用是加固圍巖，改變巖體內(nèi)摩擦角和粘聚力等力學(xué)參數(shù)，提高圍巖的整體強(qiáng)度，阻止圍巖水平和垂直位移，所以，錨桿在安裝時(shí)給予巖體足夠的正壓力是相當(dāng)重要的。 錨桿的初錨力是由預(yù)緊力矩產(chǎn)生的，它們之間存在以下簡(jiǎn)單的關(guān)系: （3） 式中: ——錨桿軸向拉力，N； T——螺母所受扭矩，N·m； d——錨桿直徑，m； K——與錨桿螺紋形式、接觸面、材料、導(dǎo)程等有關(guān)系數(shù)，一般情況下:K=0.35～0.42。 由式(3)可知，錨桿的軸向拉力與錨桿的預(yù)緊力呈線性關(guān)系，錨桿的預(yù)緊力越大，軸向拉力也越大。 7.4提高錨桿錨固力 錨桿的錨固形式為端部錨固，此時(shí)，錨桿除兩端與巖體固緊外，其余部分基本上可視為與巖體呈脫離狀態(tài)。錨桿的錨固形式為全長(zhǎng)錨固，此時(shí)，錨桿全長(zhǎng)均與巖體發(fā)生作用，即錨桿有效長(zhǎng)度均對(duì)錨孔孔壁施加摩擦力并具有剪切強(qiáng)度，它不僅提供了支護(hù)反力，而且還提高了錨固范圍內(nèi)巖體的C,Ф值。 由于全長(zhǎng)錨固錨桿實(shí)現(xiàn)了全長(zhǎng)錨固，當(dāng)圍巖發(fā)生微小不協(xié)調(diào)變形時(shí)，錨桿即可達(dá)到工作錨固力，及時(shí)提供約束力，限制圍巖的進(jìn)一步變形破壞。與此相反，端部錨固和加長(zhǎng)錨固錨桿就必須是在圍巖不協(xié)調(diào)變形發(fā)展到一定程度后，才能達(dá)到工作錨固力，在時(shí)間上要落后于全長(zhǎng)錨固錨桿，特別是端部錨固錨桿在圍巖不協(xié)調(diào)變形量很大的情況下才能達(dá)到工作錨固力，而此時(shí)圍巖的整體性已遭到了破壞，不能很好地發(fā)揮圍巖的自承能力，沒(méi)有達(dá)到加固圍巖、提高其自承能力、實(shí)現(xiàn)圍巖自穩(wěn)、控制變形的目的。 此外，端頭錨固時(shí)錨桿的工作阻力只作用在兩端，錨桿托盤的受力較大，極易引起孔口破裂、巖層被“壓酥”而破壞，產(chǎn)生卸載，使錨桿的支護(hù)阻力進(jìn)一步降低，因而失去或減小錨桿對(duì)圍巖的控制能力；而全長(zhǎng)錨固錨桿的工作阻力在錨桿中部最大，孔口較小，因而對(duì)孔附近頂板的穩(wěn)定有利，如圖1所示。 理論分析和實(shí)踐都說(shuō)明，如果一次支護(hù)有足夠的初撐力和支護(hù)阻力，有良好的讓壓性能和適當(dāng)?shù)淖寜合薅龋詈靡淮渭皶r(shí)完成全部支護(hù)，全長(zhǎng)樹(shù)脂錨固錨桿錨固力大，并且錨固及時(shí)，深部巷道高應(yīng)力、破壞速度快，應(yīng)大力使用全長(zhǎng)樹(shù)脂錨固錨桿。 7.5改善錨索性能 現(xiàn)用的小孔徑樹(shù)脂錨固預(yù)應(yīng)力錨索材料主要包括索體、錨具和托板，索體材料一般采用鋼絞線。小孔徑樹(shù)脂錨固錨索應(yīng)用初期，由于沒(méi)有煤礦專用錨索鋼絞線，只能選用建筑行業(yè)已有的鋼絞線規(guī)格。較為廣泛采用的鋼紋線由7根鋼絲組成，如圖2中(a)，為Ф15.2,Ф17.8mm，拉斷載荷分別為260, 353kN，伸長(zhǎng)率分別為3.5%,4.0%。在井下使用過(guò)程中，發(fā)現(xiàn)1×7結(jié)構(gòu)錨索有以下弊端:(1)索體直徑偏小，與鉆孔直徑不匹配，孔徑差過(guò)大，明顯影響樹(shù)脂錨固力；(2)索體破斷力小，在深井巷道中經(jīng)常出現(xiàn)拉斷現(xiàn)象；(3)索體延伸率低，不能適應(yīng)圍巖的大變形;(4)索體強(qiáng)度低，施加的預(yù)應(yīng)力水平低，導(dǎo)致錨索預(yù)應(yīng)力作用范圍小，控制圍巖離層、滑動(dòng)的作用差，當(dāng)錨索比較長(zhǎng)時(shí)尤為如此。 煤炭科學(xué)研究總院北京開(kāi)采研究所聯(lián)合有關(guān)單位，開(kāi)發(fā)出大直徑、高噸位的強(qiáng)力錨索。一方面加大了錨索索體直徑，從增加Ф5. 2增加到Ф18， Ф20, Ф22。改變了索體結(jié)構(gòu)，采用新型的19根鋼絲代替了原來(lái)的7根鋼絲，如圖2中(b)，索體結(jié)構(gòu)更加合理，而且增加了索體的柔性和延伸率。實(shí)驗(yàn)室試驗(yàn)數(shù)據(jù)表明:1×19結(jié)構(gòu)的公稱直徑分別為18，20，22mm，拉斷載荷分別為408,510,607kN，伸長(zhǎng)率均為7.0%、Ф22mm的高強(qiáng)度、低松弛鋼絞線的破斷力超過(guò)600kN，是Ф15. 2mm的鋼絞線破斷力的2. 3倍；索體延伸率比Ф15.2mm的鋼絞線提高一倍。 通過(guò)應(yīng)用新材質(zhì)、增大錨索直徑，提高錨索的延伸量和破斷載荷，使錨索適應(yīng)深部巷道圍巖大變形。 7.6加固幫、角關(guān)鍵部位 目前，我國(guó)巷道支護(hù)重視頂板、忽視兩幫和底板，頂板錨桿支護(hù)強(qiáng)度較大、兩幫支護(hù)強(qiáng)度較小、底板一般不支護(hù)，造成深部巷道兩幫及底角破碎區(qū)、塑性區(qū)很大，大范圍的破碎區(qū)圍巖發(fā)生碎漲變形，兩幫變形和底鼓十分嚴(yán)重。通過(guò)對(duì)兩幫及底角加強(qiáng)支護(hù)、注漿加固，提高兩幫及底角破碎區(qū)圍巖的殘余強(qiáng)度和錨桿錨固力，可有效阻止破碎區(qū)圍巖的碎漲變形，對(duì)深部圍巖起到支護(hù)作用，而且兩幫有效支撐頂板，阻止頂板下沉，保持圍巖穩(wěn)定，因此，控制兩幫下沉和底角破壞是深部巷道支護(hù)的關(guān)鍵。 7.7完善錨桿支護(hù)監(jiān)測(cè)系統(tǒng) 錨桿支護(hù)是一種隱蔽性很強(qiáng)的工程，只有完善錨桿支護(hù)監(jiān)測(cè)系統(tǒng)才能確保錨桿支護(hù)巷道的安全可靠性。有必要在深部巷道應(yīng)用非接觸、無(wú)損質(zhì)量的檢測(cè)儀器，儀器要具有快速、準(zhǔn)確、大面積測(cè)量的性能，以保證深部巷道的支護(hù)效果。 8 深井軟巖巷道支護(hù) 在實(shí)際的地質(zhì)條件中，有些礦井在深部的巖石為軟巖，這樣的情況下用錨桿支護(hù)就會(huì)缺少錨桿的著力基礎(chǔ)，可錨性差，支護(hù)效果不理想。一般在深井為軟巖的條件下采用錨桿注漿支護(hù)方式。 通過(guò)注漿將破碎圍巖膠結(jié)成整體，改善圍巖的結(jié)構(gòu)及其物理力學(xué)性質(zhì)，既提高圍巖自身的承載能力，又為錨桿提供了可靠的著力基礎(chǔ)，使錨桿對(duì)松散圍巖的錨固作用得以發(fā)揮。采用注漿錨桿注漿，可以利用漿液封堵圍巖裂隙，隔絕空氣，防止圍巖風(fēng)化，且能防止圍巖被水浸濕而降低圍巖的本身強(qiáng)度，提高圍巖的穩(wěn)定性。利用注漿錨桿注漿充填圍巖裂隙，配合錨網(wǎng)噴支護(hù)，可以形成一個(gè)多層有效組合拱，即噴網(wǎng)組合拱，錨桿壓縮組合拱及漿液擴(kuò)散加固拱，從而擴(kuò)大了支護(hù)結(jié)構(gòu)的有效承載范圍，提高了支護(hù)結(jié)構(gòu)的整體性和承載能力，從而有效地控制深部軟巖巷道的大變形。 與錨桿支護(hù)相比，錨注支護(hù)既加固了圍巖，又給錨桿提供了可靠的著力基礎(chǔ)，使圍巖強(qiáng)度和承載能力得到顯著提高，巷道變形量明顯降低，錨注支護(hù)可以較好地解決深部軟巖巷道的支護(hù)問(wèn)題。采用錨注支護(hù)技術(shù)，將松散破碎的圍巖膠結(jié)成整體，提高了巖體的強(qiáng)度，使巷道保持穩(wěn)定而不易破壞。利用注漿充填圍巖裂隙，配合錨網(wǎng)噴支護(hù)，可以形成一個(gè)多層有效組合拱，極大地提高了支護(hù)結(jié)構(gòu)的整體性和圍巖的自身承載能力。錨注支護(hù)技術(shù)的應(yīng)用解決了高應(yīng)力軟巖巷道的支護(hù)問(wèn)題。 9結(jié)論 深井巷道所處的圍巖環(huán)境復(fù)雜多變，影響巷道穩(wěn)定的主觀因素與客觀因素之間又相互影響，它們之間與巷道穩(wěn)定的關(guān)系很難用統(tǒng)一的理論公式進(jìn)行歸納總結(jié)，因此對(duì)于深井巷道支護(hù)要取得良好的支護(hù)效果，就必須加強(qiáng)地應(yīng)力測(cè)試與現(xiàn)場(chǎng)礦壓觀測(cè)，靈活采用支護(hù)加固方式，并及時(shí)調(diào)整支護(hù)加固參數(shù)，必要時(shí)對(duì)高應(yīng)力區(qū)先卸壓后支護(hù)加固，這樣更有利于巷道穩(wěn)定。 參考文獻(xiàn): [1] 陸士良，等.錨桿錨固力與錨固技術(shù)[M].北京:煤炭工業(yè)出版社，1998； [2] 李國(guó)富，等.極軟巖巷道錨注支護(hù)技術(shù)的研究與應(yīng)用[J].巖石力學(xué)與工程學(xué)報(bào)，2002,(4)； [3] 李明遠(yuǎn),等.軟巖巷道錨注理論與實(shí)踐[M].北京:煤炭工業(yè)出版社，2001； [4] 何滿潮，等.中國(guó)煤礦軟巖巷道工程支護(hù)設(shè)計(jì)與施工指南[M].北京:科學(xué)出版社.2004； [5] 陳炎光，陸士良，中國(guó)煤礦巷道圍巖控制[M].徐州:中國(guó)礦業(yè)大學(xué)出版社，1994； [6] 柏建彪，侯朝炯.深部巷道圍巖控制原理與應(yīng)用研究[J].中國(guó)礦業(yè)大學(xué)學(xué)報(bào)，2006,35(2),145-148； [7] 康紅普，王金華，林健.高預(yù)應(yīng)力強(qiáng)力支護(hù)系統(tǒng)及其在深部巷道中的應(yīng)用 [J].2007,32(12);1233-1238； [8] 耿富強(qiáng).徐州礦區(qū)深部巷道礦壓顯現(xiàn)特征及對(duì)策[J].煤炭科技。 任務(wù)書 學(xué)院 專業(yè)年級(jí) 學(xué)生姓名 任務(wù)下達(dá)日期：20xx年1月8日 畢業(yè)設(shè)計(jì)日期：20xx年3月12日 至 20xx年6月8日 畢業(yè)設(shè)計(jì)題目： 陳四樓煤礦2.4Mt/a新井設(shè)計(jì) 畢業(yè)設(shè)計(jì)專題題目： 深部礦井巷道支護(hù)技術(shù) 畢業(yè)設(shè)計(jì)主要內(nèi)容和要求： 以實(shí)習(xí)礦井陳四樓煤礦條件為基礎(chǔ)，完成陳四樓煤礦2.4Mt/a新井設(shè)計(jì)。主要內(nèi)容包括：礦井概況、礦井工作制度及設(shè)計(jì)生產(chǎn)能力、井田開(kāi)拓、首采區(qū)設(shè)計(jì)、采煤方法、礦井通風(fēng)系統(tǒng)、礦井運(yùn)輸提升等。 結(jié)合煤礦生產(chǎn)前沿及礦井設(shè)計(jì)情況，撰寫一篇專題論文。 完成近3-5年國(guó)外期刊上與采礦或煤礦安全有關(guān)的科技論文翻譯一篇，要求不少于3000字符。 符。 院長(zhǎng)簽字： 指導(dǎo)教師簽字： 翻 譯 部 分 英文原文 Mine gas drainage and outburst control in Australian underground coal mines Naj Aziza, Dennis Blackb and Ting Rena School of Civil, Mining & Environmental Engineering, University of Wollongong, NSW 2522, Australia PacificMGM, Mining and Gas Management Consultants, Wollongong, Australia. Abstract: Australia produces both black and brown coal and is the world’s fourth largest producer of black coal, after China, USA and India. Australian underground coal mines operate under controlled safety codes. The establishment of the mine safety management system, including the 1994 outburst management plan, contributed to a significant improvement in mine safety leading to non-fatality in outburst related incidences since 1994. The management of outburst risk, as a part of the overall safety and health management system is described. Also discussed are the introduction of outburst threshold limit values and the desorption rate index which forms the basis for determin -ing safe mining conditions along with the “Authority to Mine” process. The measures taken and lessons learned from safe mining of Australia’s outburst prone mines represent an opportunity for improved mining safety in other countries, such as China. . The role of the Australian Coal Association Research Program, which supports research in critical areas such as outburst risk control and management, is also discussed. Keywords: Mine, Gas, Outburst, Mine safety management,Threshold limit values, Risk management; 1. Introduction Australia produces both black and brown coal and is the world’s fourth largest producer of black coal, after China, USA and India, and the fifth largest producer of brown coal, after Germany, Russia, Turkey and USA. In 2009, Australia produced approximately 346 Mt of saleable black coal from 451 Mt of total raw coal production, and approximately 68 Mt of brown coal [1][2]. Almost 98% of Australian black coal production is sourced from the two eastern states of New South Wales (NSW) and Queensland (QLD) while brown coal is produced mainly in Victoria, with 98% coming from the Latrobe Valley. All of the brown coal production is utilised within Victoria for power generation. In 2009, Australia supplied 29% of global black coal export market, and has been the leading exporter of black coal since 1984. Black coal is Australia’s principal export commodity, generating a $55 billion in revenue for the nation last year. Australia produces and exports both metallurgical and thermal coal in approximately equal proportions. The majority of Australia’s metallurgical (coking) coal is produced in Queensland, while New South Wales produces predominantly thermal (steaming) coal. The Australian coal mining industry directly employs approximately 30 000 people and indirectly supports the employment of a further 100 000 people who provide services to the coal industry. Coal seam gas represents a potentially significant risk to the safety and productivity of underground mines. Ineffective control and management of coal seam gas increases the risk of creating conditions that may result in either a coal and gas outburst or a methane and coal dust explosion. Poor gas management may also lead to general body gas concentrations exceeding statutory limits necessitating the cessation of production activities within the affected area. Over 730 outbursts have occurred in Australian mines since 1895. Table 1 lists both fatal and other incidents related to coal seam gas explosions and gas outbursts. Such incidents have shaped coal mine legislation and operating practices and provide the motivation to develop and maintain safe working conditions and operating practices. Many of the leading Australian coal mining companies now strive for “Zero Harm” and significant resources are dedicated to achieving this goal. Australian mining now relies on the use of Safety and Health Management Systems (SHMS) that identify hazards and other potential risks present at individual mines and requires the development of management plans and operating procedures that detail the process to identify and assess hazards and implement appropriate controls to reduce risks to as low as reasonably achievable. The management of the Mine/Colliery is required to reduce and minimise the risks associated with outbursts in development panels and on longwall faces. This aim is achieved by the drainage of inseam gas to reduce in situ content to below defined Threshold Limit Values (TLV) and implementing a system of measurement and assessment of outburst risk prior to authorising mining activities to take place in any part of the mine. 2. Outburst Risk Management The Outburst Management Plan (OMP) [6] is an integral part of a mine’s SHMS and is developed and maintained to effectively control the risks associated with the outburst hazard. An example of a typical relationship between the OMP and other components of the mine SHMS is illustrated in Fig. 1. Table 1: Gas explosions and outburst incidents in Australia * (updated from [3] [4] and [5]) Colliery Date Seam Basin Depth (m) No of O/B No. Killed Gas Ejected coal size (t) Work Place Metropolitan* 1895- pres. Bulli Sydney 425 154 (tot) - CO2 Mainly with CH4 200 Pick Metropolitan 1896 Bulli Sydney 425 3 Firedamp Single shot Metropolitan 1926 Bulli Sydney 400 2 Black damp 140 undercutting Metropolitan 1954 Bulli Sydney 425 2 CO2 90 Undercutting Metropolitan 1961 Bulli Sydney 425 CO2 +CH4 300 Induced shotfiring North Bulli 1911 Bulli Sydney 370 CH4 1 Pick-delayed Coal Cliff 1961 Bulli Sydney 450 CO2+CH4 2 Cont Miner Corrimal 1967 Bulli Sydney 400 4 CO2 +CH4 50 Cont Miner Appin 1966 Bulli Sydney 520 CH4 60 Cont Miner Bulli 1972 Bulli Sydney 380 CH4 100 Cont Miner West Cliff 1977- 93 Bulli Sydney 460 253 CH4 4-300 Cont Miner Collinsville 1954- 1978 Bowen 220 19 CO2 400 C.C.C.P 1978 Bowen 280 25 Cont Miner Leichardt 1975 Bowen 370 CH4 500 Cont Miner Tahmoor 1985 Bulli Sydney 90* 1 CO2 Cont Miner *Since 1981 South Bulli 1991 Bulli Sydney 3 CO2 300 Development West Cliff 1994 Bulli Sydney 1 CH4 Development Central 2001 German Ck Bowen 400 1 CH4 60-80 Development Brimestone /Oakdale 1992- 1995 Bulli Sydney 2 CH4 +CO2 10 Development Kemira 1980-1 Bulli Sydney 2 CH4 6-100 Development Tower 1981 - 2000 Bulli Sydney 19 CH4 1-80 Development *Since 1981 Appin 2010 Bulli Sydney 3 CH4 +CO2 Development Total Number of outbursts > 730 The prime objective of the Mine/Colliery OMP is to facilitate exploratory inseam drilling and gas drainage with the aim of reducing in situ coal seam gas contents, in all areas of the mine where development and longwall operations (and subsequent longwall extraction) are to be carried out. Reducing the pressure and content of gas within the coal seam through focussed gas drainage has been proven in Australia to be the most effective control to ensure that the risk of an outburst (or other release of dangerous quantities of noxious or flammable gas) is minimised and allows normal mining operations to be carried out. In exceptional circumstances, where conditions within the coal seam prevent effective gas drainage, the OMP makes allowance for alternate mining procedures to be used, under strictly controlled and considered circumstances. In all circumstances the intent of the OMP is to maintain the protection provided to employees and the operation. The OMP applies to all employees of the Colliery who are engaged in development mining, longwall mining, gas drainage or associated tasks and any other parties associated with the application of the OMP. It covers the strategies associated with prediction and prevention techniques as well as methodologies associated with the protection of personnel and the operation from the effects of an outburst. If a coal seam is identified to be outburst prone, it is a requirement for the Mine/Colliery operating in such coal seam to develop and operate in accordance with an outburst management plan (OMP). This plan has been developed to address the risk of a gas induced outburst. The OMP’s prime operational objective is to carry out effective in-seam drilling and gas drainage, sufficiently in advance of development mining, in order to reduce in situ seam gas contents to below the normal mining thresholds and allow mining to be carried out under normal conditions. The main elements of the plan include Prediction, Prevention and Protection (Control). Fig. 1 Mine safety management system 2.1 Prediction There are several factors that are accepted as the key parameters associated with outburst prediction. The geological structures of coal, excessive gas content and ground tectonic stresses are the key factors. In general, geological structures are likely to be the location of any outbursts. Geological structures are considered to present an increased risk of outburst as such structures may create stress concentrations and create a barrier that results in a high gas pressure differential. The detection of geological structural anomalies ahead of mining is achieved by in-seam drilling and the nature of the anomalies are subsequently elaborated through the use of various geophysical logging methods such as 2D and 3D seismic surveys, and the use of other technologies such as radio imaging and radar. Other methods of gas outburst prediction tools include the prediction indices [7] and using tube bundle and/or real time gas monitoring systems to detect the gas concentrations throughout the mine. In each mine the mine geologist will be responsible for the collection, analysis (with regard to outburst potential) and maintenance of the data; the mine surveyor [8] will be responsible for a drill log summary sheet for each in-seam borehole drilled within the Colliery for the purpose of exploration, structure prediction core sampling or gas drainage and plot any anomalies recorded by drillers onto the Surveyors plan, independent of the geological interpretation of that data. The gas drainage engineer will establish documented standards and assessments for drilling of in-seam boreholes, connecting the drainage holes to the gas drainage system in the mine, and the monitoring of gas flows from boreholes, and maintenance of the gas drainage system to maximise effectiveness and the safe means of clearing a borehole suspected of being blocked. Other responsibilities of the mine geologist, the surveyor and the gas drainage engineer are described in the New South Wales Department of Mineral Resources OMP [6] 2.2 Prevention This is related to the effectiveness of gas drainage coupled with gas flow monitoring, and regular core sampling, so that the mine manager is always aware of the seam gas and structural environment into which the mine is about to develop or extract. Prevention of outburst during mining of development roadways is achieved by the deployment of gas drainage in reducing seam gas contents to below the appropriate threshold value for the composition of the prevailing seam gas. Both prediction and prevention form the input into the Authority to Mine (ATM) process which, upon completion, will determine the mining methodology to be used to develop each roadway or sequence of roadways and extract longwall panels. 2.3 Protection or Control This is offered to development operators by way of routine training in outburst awareness, the identification of outburst warning signs and use of first response rescue and escape equipment, the provision of that equipment in the development panel at all times and the ability to suspend mining and initiate an inspection at any time should outburst warning signs be observed. Various systems and measures, which contribute to control/or protection from outbursts to include: 1．Ground destressing, which includes stress relief drilling, stress relief mining, inducer shot firing and gas drainage. 2．The use of OMPs[6], 3．Hydraulic fracturing; a method that has increasing application both for UIS and SIS operations, 4．Pulse infusion shot firing, and 5．Water infusion. Pulsed infusion shot firing and water infuse are not generally used in Australia. 3. Authority to Mine (ATM) The prediction and prevention provisions are designed to develop a clear picture of the conditions prevailing ahead of development panels and to reduce the seam gas content to below the threshold value corresponding to the seam gas composition prevailing in that area. The data generated as a result of the prediction and prevention provisions provide the input into the Authority to Mine process. The method of working will be decided for each set of circumstances by using the available and recognized outburst decision making flowchart[6]. The Outburst Risk Review Team (ORRT) will be responsible for and manage the ATM process. The ATM will be co-authorised by the mine manager, undermanager-in-charge and the gas drainage engineer. ORRT is a group responsible under the OMP to review data relevant to outburst risk at the mine and to manage mining activities through the ATM process. The group normally consists of mine manager, gas drainage engineer or ventilation coordinator, undermanager-in-charge, gas drainage engineer, mine geologist, workforce representative and development coordinator. The mine manager, undermanager-in-charge and gas drainage engineer are responsible for approving an ATM. 4. Threshold Limit Values (TLV) Following the last outburst related fatality in Australia, which occurred at West Cliff Colliery, Illawarra Coalfield, Sydney Basin, on 25th January 1994, the NSW Department of Mineral Resources (DMR) issued a directive to all mines operating in the Bulli seam detailing actions to be implemented to prevent further outburst related fatalities. Arguably the most significant of these actions was the stipulation of limits on seam gas content prior to mining, known as outburst Threshold Limit Values (TLV). Fig shows the Bulli seam TLV prescribed by the DMR [9]. The TLV varied linearly based on gas composition, decreasing from a maximum in CH4 rich conditions to a minimum in CO2 rich conditions. The Level 1 TLV indicates the maximum gas content limit for normal mining above which outburst mining procedures must be followed. The Level 2 TLV indicates the maximum gas content limit for outburst mining above which mining must only be undertaken using remote operated equipment, with all personnel remaining clear of the outburst risk zone. Fig. 2 Prescribed Bulli seam Outburst Threshold Limits [9] Lama [10] described the process that led to his recommendation of TLV for safe mining of the Bulli seam, based on total gas content. The Level 1 TLV of 6.4 m3/t for CO2 and 9.4 m3/t for CH4 are considered safe under all circumstances, i.e. when mining in close proximity to geological structures with a development advance rate up to 50 m/d. Lama [10] suggested that if the rate of development advance was reduced to 10-12 m/d the Level 1 TLV could be safely increased by 20%. Lama also proposed a Level 2 TLV of 10.0 m3/t and 12.0 m3/t for CO2 and CH4 when it was known that no geological structures were present within 5.0 m of the excavation during roadway development in virgin areas. In presenting the TLV, Lama [8] stated the proposed TLV would include a safety factor of 19% (1.1 m3/t), considered higher than the error in gas content measurement. In recent times a few mines are operating at varied TLV values with approval from the DMR inspectorate. At Tahmoor Colliery for example, in addition to the Level 1 TLV, below which no restrictions are placed on mining, two additional TLV levels were introduced. The Level 2 TLV applies to structured coal. Where the measured gas content is greater than Level 1 and less than Level 2, in addition to more intensive drilling and coring, the rate of development advance is restricted to 12 m/d. The Level 3 TLV applies to coal free of geological structures. Where the measured gas content is greater than Level 1 and less than Level 3, in addition to increased drilling and gas content testing, the rate of development advance is restricted to 25 m/d in each heading and cut-through to a maximum of 75 m in any 24 hour period. In areas where gas content remains above the defined TLV, normal mining is prohibited and grunching is the only approved development mining method. At West Cliff Colliery, in addition to the Level 1 TLV, one additional TLV was introduced. While no restrictions are placed on the rate of development advance, where the measured gas content is between the Level 1 and Level 2 TLV increased drilling, structure identification and gas content testing is required. Where the gas content remains above the Level 2 TLV normal mining is prohibited and an alternative mining method, such as remote control or grunching, shall be used. Williams and Weissman [11] introduced the concept of using the rate of gas desorption from crushed coal, during Q3 testing, known as Desorption Rate Index (DRI), to determine TLV applicable to coal mines operating in coal seams other than the Bulli seam. The test involved measuring the volume of gas emitted from a 200 g sub-sample of coal material after crushing for 30 seconds and extrapolating the result to the total gas content (QM) of the full core sample to determine the DRI of the full coal sample (Williams, 1996 [12] and Williams, 1997 [13]). The data presented in Fig, which represents data collected from the 386 panel at West Cliff Colliery [14] demonstrate a strong correlation between Q M and DRI for both CO2 rich and CH4 rich coal samples. The relationship was assumed by Williams and Weissman [10] to be representative of all Bulli seam conditions. As shown in Fig.3, the Bulli seam TLV of 9 m3/t (100% CH4) and 6 m3/t (100% CO2) correspond to a common desorbed gas volume of 900 mL. From this assessment, Williams and Weissman concluded that the QM value corresponding to a DRI of 900, based on a unique QM-DRI relationship determined specifically for each mine and coal seam, represent the TLV applicable to that coal mine. Fig. 3 QM relative to DRI for CO2 and CH4 rich coal from 386 panel [13] 5. The Role of Research Research on coal and gas outburst goes back some fifty years and the pioneering work of Hargraves [15]. Hence the Australian coal mining industry is served by a number of research activities and research organizations such as Commonwealth Scientific and Industrial Research Organization (CSIRO), university research, consultants and individual mining companies. Funds can be obtained from the Australian Coal Association Research Program (ACARP) research and development (R&D) investment program. This program is funded by a A$0.05 per saleable tonne levy that is managed by representatives of the coal industry. ACARP has been in operation since 1992 and currently supports research activities into the safe and sustainable production and marketing of coal [16]. With an expenditure of about A$15 million per year, the program supports a critical mass of R&D activities covering issues determined by the ACARP committee members to be of interest to coal producers and other key stakeholders. Fig. 4 shows the distribution of direct ACARP funds [17], which amounts to around A$50 million over the last five years. Underground projects have attracted some 36% of the pool, which has been expanded by the wind down of funding for the low emissions coal use committee since 2008. In 2011, around 10-15% of the total A$15 million was allocated to coal mine gas and outburst and gas drainage