【正文】 ed support applied at the face is 717 ton while, in the advance gallery, it is 154 , a support of capacity 750 ton at the face and a travelling support of 160 ton applied in the advance gallery will be adequate to extract the developed pillars of Balrampur mine. The results indicated that a support density of ton/m2 is the required load density at the face. Table 6 Load on support at the face and in the advance gallery with different rib thickness Support capacity Rib thickness (m) Load on powered supports at face (t) Support resistance (t/m2) Load on gallery support (t) 450T 5 Yield load —— 3 Yield load —— 1 Yield load —— 0 Yield load —— 525T 5 515 3 Yield load —— 1 Yield load —— 0 Yield load —— 600T 5 509 3 577 1 Yield load —— 0 Yield load —— 650T 5 510 3 573 1 Yield load —— 0 Yield load —— 700T 5 509 3 573 1 Yield load —— 0 Yield load —— 750T 5 509 3 573 1 708 0 717 8. Discussion and conclusions The intact rock properties of different layers of the overlying strata above the Passang seam of Balrampur mine have been calibrated with ?eld observations taken over an experimental panel P1 for the numerical modelling purposes. These calibrated properties have been utilized for the prediction of expected main fall, suitable orientation of the shortwall face with respect to the advance gallery, and the required support density at the face and in the advance gallery under different binations of the hard cover. The following conclusions from the above study have been remended for extraction of the developed pillars of the Balrampur mine with high productivity by the shortwall mining method. (a) Support requirement at the face: The maximum load ing on the powered support applied at the face is 717 ton. Therefore, a support resistance of 2/mton will be adequate to prevent failure of the immediate roof as the face approaches the advance gallery. The overhang of the strong bed number BedII must be limited to 15m from the face by blasting. Further, the canopy length should be chosen such that the face span during normal longwall conditions should not be exceeded by after the cut. (b) Support requirement in the advance gallery: The 440 ton traveling supports (made of 4 hydraulic props of 40 ton each with canopy width 2m and length 3m) will be suf?cient in the advance gallery. A minimum of three such travelling supports are required so as to cover a length of 9m in the advance gallery at an obliquity of 9176。. Maximum load on the supports in the event of failure of the 1m rib is expected to be 154 ton over a length of 3m in the advance gallery. Over and above the support remended in the advance gallery, the immediate roof may be further strengthened by four rows of roof bolts long, at a spacing of 1m, along the advance gallery and in the level galleries also. The junctions should be supported by Wstraps along with bolts. (c) Face obliquity and stability of the triangular rib: It is found that, with an obliquity of 9176。, the advance gallery is crossed once in the entire face. Hence, the zone of intense strata movement is also reduced. The safety factor of a 1m thick triangular rib with 9176。obliquity is . It is expected that a rib of safety factor of this level will stand for sufficient time to enable the shortwall face to cross an advance gallery. The face should not be kept idle while crossing this triangular rib. (d) Expected main fall: From the study of 3D modelling of the developed bord and pillar workings of the Balrampur mine, the expected main fall at different depth of cover with varying hard cover is summarized below. Depth of cover Extraction width Expected main fall 50m（ 30m hard cover +20m weathered rock） 5 pillars wide Between 90 and 100m 50m（ 30m hard cover +20m weathered rock） 4 pillars wide 110~120m 40m（ 30m hard cover +10m weathered rock） 4 pillars wide 140~150m 40m（ 20m hard cover +20m weathered rock） 4 pillars wide 100~110m Acknowledgements The authors are thankful to the Director, CMRI Dhanbad, for granting permission to publish this work. The authors also thank Mr. . Roy and Dr , scientists of the Longwall Mining Division of CMRI, for providing the input data of the Balrampur mine and Mr. Rana Bhattarchjee, JSA, and Mr. Suman Kumar, Project Assistant of Bord and Pillar Mining Division, for their assistance in preparing the paper. The opinions expressed in the paper are those of the authors and not necessarily of the Institute to which they belong. 中文譯文 案例分析 — 用短壁開采的方式來回收煤柱 A. Kushwaha， G. Banerjee 中央采礦研究所，巴瓦路，丹巴德， 826001，加爾克漢德邦，印度 摘要： 短壁開采技術(shù)和長壁開采技術(shù)十分相似，但是其工作面長度較短，范圍在 40~90m 之間，旨在控制上覆巖層的垮落，以及工作面支架的工作阻力和工序的正常運(yùn)轉(zhuǎn)。通過對 SECL 的巴爾蘭普爾礦巴山煤層進(jìn)行了現(xiàn)場觀察以及三維數(shù)值模擬，研究了上覆巖層的垮落特征。鄰近長壁采區(qū)的巴山煤層的大片區(qū)域是通過房柱式開采的。本論文，通過數(shù)值模擬來評估房柱式開采后巴山煤層上 覆巖層的垮落特性，并且預(yù)測了不同長度工作面、埋深、巖性的上覆巖層的大面積垮落特征。最后，為了對巴爾蘭普爾礦進(jìn)行短壁開采回收煤柱，估計(jì)了工作面所需要的支護(hù)阻力、巷道超前支護(hù)所需阻力、以及巷道最佳的調(diào)斜角度。 關(guān)鍵詞： 開采；短壁開采；調(diào)斜角度；立體云圖；大面積來壓；超前巷道 1 引言 在印度，盡管房柱式開采每人每班的產(chǎn)量不會(huì)超過 1t，但是絕大多數(shù)地下開采礦井仍然依賴這種方式。印度煤業(yè)公司的所有分公司都是用房柱式采煤法開采的，即使是 Singarani 煤業(yè)公司也是如此。為了提升產(chǎn)量，需要研究快速回采煤柱的方法。 在本文中，作者用 FLAC 進(jìn)行了不同的數(shù)值模擬研究，據(jù)此評價(jià)了巴爾蘭普爾礦巴山煤層在用房柱式采煤方法回采結(jié)束后上覆巖層的穩(wěn)定性。通過對長壁采區(qū)頂板巖石進(jìn)行現(xiàn)場觀測和實(shí)驗(yàn)分析，得到的巖石力學(xué)參數(shù)即是數(shù)值模擬用到的參數(shù)依據(jù)。對不同工作面長度、巖層特性、煤層埋深的上覆巖層進(jìn)行了模擬，預(yù)測了頂板大面積來壓的跨距。并且，為了提高開采速度及安全性，估計(jì)了短壁回采回收煤柱工作面的最佳調(diào)斜角度。 2 短壁開采 當(dāng)埋深較大時(shí)，房柱式開采在生產(chǎn)效率、安全性方面不是一個(gè)合適的方法。短壁開采技術(shù)客服了長壁開采的很多限制。通過總 結(jié)研究印度的長壁綜采，配備中等價(jià)格采煤機(jī)的90m 長的工作面是經(jīng)濟(jì)最優(yōu)的。在已采過的房柱式采區(qū)進(jìn)行短壁開采可以克服傳統(tǒng)房柱式開采的諸多限制。 專業(yè)術(shù)語表 符號 意義 符號 意義 бh 水平原巖應(yīng)力 b 失效準(zhǔn)則指數(shù) E 彈性模量 бcm， бtm， бm 與完整巖石對應(yīng)的 巖體強(qiáng)度常數(shù) v 泊松比 RMR 比尼奧斯基指數(shù) бv 垂直原應(yīng)力 τsm 巖體剪切強(qiáng)度 β 熱脹系數(shù) μom 巖體剪切強(qiáng)度 G 地?zé)崽荻? υom 巖體內(nèi)摩擦角 б1。 б3 最大和最小主應(yīng)力 S 煤柱強(qiáng)度 бc 完整巖石抗壓強(qiáng)度 P 煤柱載荷 H 埋深 W 煤柱寬度 бt 完整巖石抗拉強(qiáng)度 H 煤柱高度 EMS 每人每班工資 B 巷道寬度 OMS 每人每班產(chǎn)出 3 巴爾蘭普爾礦巴山煤層的現(xiàn)狀 巴爾蘭普爾礦所提到的短壁采區(qū)的地質(zhì)條件如下 煤厚： ；采高： ；采區(qū)深度； 37~50m；煤層上方或下方現(xiàn)有的開采區(qū)域：無；現(xiàn)有采礦方式：房柱式開采；煤柱尺寸： 20m20m（中