The 3rd issue of the journal, Vol.2, N. 1, January-June 2013 ... - ISRM

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10 ISRM (India) Journal• Brazilian Tensile StrengthThe tensile strength of rock is determined using Brazilianmethod. Both parallel and perpendicular to foliation aredetermined so as to fix the cutters to take this advantage.Values are higher when the samples are loadedperpendicular to foliations.• Young’s Modulus of Elasticity & Poisson’s RatioThe Young’s Modulus of elasticity (tangent) wasmeasured in MTS stiff testing machine using straingauges (balanced). The data were acquired by a dataacquisition system (SPIDER 8).• Thin section analysisMineralogical studies were also done to understand thehard minerals present alongwith their texture, orientationetc. Microphotographs of two rock types are shown inFigure 2 a & 2b.3.1 Summary of Laboratory InvestigationsOf the seven rock types tested, the quartzite rockshave the lowest DRI value (52). Metabasic Rock andMica Schist have the highest DRI value, i.e., more than79. Low DRI values indicate difficult boreability for theTunnel Boring Machine, in general, where as higherDRI values indicate easier boreability. The CercharAbrasivity Index (CAI) for the Quartzite rock was foundto be 5.62 which indicates that there will be high rate ofwear in TBM cutters when compared to other rock typesmentioned above. Higher abrasivity of quartzite andcoarse-grained gneiss, weak strength of metabasic rockare some of the typical observations in these rock suits.The Young’s Modulus of elasticity was the highest forquartzite (55.5 GPa) and the lowest for the metabasicrocks (7.8 GPa).Fig. 2a : Thin Section of Metabsic rockFig. 2b : Thin Section of QuartziteDifferent test setup and the results on different rock suits supplied from Tapovan-Vishnugad project are provided inFigure 3 and Table 5 respectively.Table 5 : Rock properties of different rock suits, Tapovan-Vishnugad Hydel Project (Murthy, 2005)Name of rock BI Sj DRI CAI UCS (MPa) BTS (MPa) MOE (GPa) Poisson’s RatioMetabasic rock 69.5 53.2 79 2.40 84 (52-107) 6.7-8.3 7.8(5.8-9.5)Augen Gneiss 52.4 31 58 3.42 91 (61-125) 8.4-8.7 27.9(24-29)0.26(0.16-0.33)0.23(0.18-0.30)Coarse grained Gneiss 63.2 28.6 69 4.35 77 (63-88) 7.3-7.9 35 (23-48) 0.27(0.10-0.40)Foliated Gneiss 63.5 5.5 62 3.50 98 (84-114) 7.3-10.1 36.7(34-40)Fine grained Gneiss 58.7 16 61 3.00 196(143-236)Quartzite 55.6 3.83 52 5.62 184(103-254)6.9-8.4 36.1(29-42)7.8-8.7 55.5(45-63)Mica Schist 70.3 107.5 86 2.28 Regular core sample could not be obtained0.24(0.17-0.34)0.14(0.11-0.16)016(0.15-0.18)Volume 2 No. 1 January 2013
Role of Geology and Special Rock Mechanics Tests in TBM Tunnelling – A Perspective11(a) Siever’s J value (Sj)(b) Brittleness index(BI)(c) Cerchar Abrasivity Index (CAI)(d) Nomogram for estimation of DRI(e) Uniaxial Compresssive strength(f) Brazilian Tensile Strength(g) Setup for the determination of Young Modulus(h) Analysis for computing MOE and Poisson’s RatioFig. 3 : Laboratory test setup for TBM application, ISM, DhanbadVolume 2 No. 1 January 2013
Page 3 and 4: CONTENTSPage No.From Editor’s Des
Page 5 and 6: Influence of Anisotropic Stress Con
Page 7 and 8: Role of Geology and Special Rock Me
Page 11: Role of Geology and Special Rock Me
Page 19 and 20: Influence of Anisotropic Stress Con
Page 21: Influence of Anisotropic Stress Con
Page 24 and 25: 22ISRM (India) Journaldriven perpen
Page 26 and 27: 24ISRM (India) JournalFig. 9 : Plot
Page 28 and 29: 26 ISRM (India) JournalThe soft nat
Page 30 and 31: 28 ISRM (India) JournalInitially, 5
Page 32 and 33: 30 ISRM (India) Journal4.4 Immediat
Page 34 and 35: ISRM (India) JournalMr. Devendra K.
Page 36 and 37: 34 ISRM (India) JournalRecent Activ
Page 38 and 39: 36 ISRM (India) JournalLighting of
Page 40 and 41: 38 ISRM (India) Journal• Managing
Page 42 and 43: 40 ISRM (India) JournalA view of th
Page 44 and 45: 42 ISRM (India) JournalA Tribute to
Page 46 and 47: 44 ISRM (India) Journaland 86.9m in
Page 48 and 49: 46 ISRM (India) JournalRecipients o
Page 50 and 51: 48 ISRM (India) JournalPUBLICATIONS
Page 52 and 53: ISRM (India) JournalRECOGNITIONSDr.
Page 54: 52 ISRM (India) JournalCALL FOR PAP

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