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Rock Mass Rating RMR Geological Strength Index GSI and Slope Rock Mass Ra ting SRMR classification systems 3 Table 1 indicates the results of the classifi cation of the rocks of the western wall in Chadormalu iron ore mine Results obtained from this table indicate that the quality of the rocks in the west wall area in Chadormalu mine is poor due to breakings and
Rock Mass Classification 82 Terzaghi s Rock Load Theory Terzaghi 1946 Classification 1969 Rock Structure Rating RSR Wickham 1974 Rock Mass Rating RMR Bieniawski 1973 1984 Rock Mass Quality Q Barton et al 1974 Geological Strength Index GSI Hoek and Brown 1997 Most Used Downloaded June 13 2011 World Tunnelling March
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Download as PDF Set alert About this page Rock Mass Rating Bhawani Singh R K Goel in Engineering Rock Mass Classification 2011 Publisher Summary The geomechanics classification or the rock mass rating RMR system was initially developed at the South African Council of Scientific and Industrial Research CSIR on the basis of experiences in shallow
disturbed rock mass when determining parameters in the failure criterion for which clear guidelines are lacking Also the modified Hoek Brown criterion gives physically questionable values for the rock mass strength and should be used with caution in low stress environments It is recommended that the original Hoek Brown criterion instead be used routinely Many
On the basis of RMR values for a given engineering structure the rock mass is sorted into five classes very good RMR 100–81 good 80–61 fair 60–41 poor 40–21 and very poor lt 20 It must be ensured that double accounting for a parameter is not done in the analysis of rock structures or in estimating the rating of a rock mass
Laubscher s Mining Rock Mass Rating MRMR sys tem was introduced in 1975 Laubscher 1975 and has been modified and expanded several times since then Laubscher 1990 1993 Laubscher and Taylor 1976 The last update was released in 2000 Laubscher and Jakubec 2001 The principal changes in the new In Situ Rock Mass Rating IRMR included the
The empirical method of Rock Mass Rating RMR Q system is often utilised for the rock mass classification of tunnel projects The proposed system includes visual judgement of the rock material and rock mass with a relatively wide range of definition contrary to the RMR or Q system One of the empirical methods of Geological Strength Index
Rock mass class Excavation b y drill amp blast Rock support for 10m wide tunnels Rock bolts Steel sets 20mm diam fully bonded Shotcrete 1 Very good rock RMR 81 100 Full face 3m advance Generally no support required except for occasional spot bolting 2 Good rock RMR 61 80 Full face 1 0 1 5m advance Complete support 20m from face
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Rock mass classification Introduction During the feasibility and preliminary design stages of a project when very little detailed information is available on the rock mass and its stress and hydrologic characteristics the use of a rock mass classification scheme can be of considerable benefit At its simplest
Engineering Rock Mass Classification Tunneling Foundations and Landslides Bhawani Singh Former Professor of Civil Engineering Indian Institute of Technology Roorkee 247 667 India R K Goel Scientist G Central Institute of Mining and Fuel Research Regional Centre CBRI Campus Roorkee 247 667 India Edinburgh London New York Oxford Philadelphia St Louis Sydney
considered to be weak if it has a rock mass rating RMR 4 of less than 45 and or a rock mass quality rating Q under 1 0 In areas where rock quality allows the mines employ a version of longhole open stoping 5 Where spans from the footwall to the hanging wall exceed 7 6 m transverse open stoping is employed with the use of primaries and secondaries
Rock mass class I Very good rock 81 100 11 Good rock RMR 61 80 Ill Fair rock RMR 41 60 IV Poor rock RMR 21 40 V Very poor rock RMR lt 20 Excavation Full face 3 m advance Full face l I 5 m advance Complete support 20 m from face Top heading and bench 1 5 3 m advance in top heading Commence support after each blast
chose the Rock Mass Rating propos ed by Bieni awski 5 Because of the lack of suitable alternatives the criterion was soo n adopted by the rock mechanics community and i ts use quickly spread beyond the original limits used in deriving the strength reduction relationships Consequently it became necessary to re examine these relationships and to introduce new
Rock Mass Classification is the process of placing a rock mass into groups or classes on defined relationships Bieniawski 1989 and assigning a unique description or number to it
This is very pronounced for the slate unit in Table 4 1 for which relatively high friction angles were achieved despite the low intact rock strength and rock mass quality rating for this rock type To compare these values additional estimates were done by the author using values for disturbed rock mass Equations 2 6 and 2 7
Later revisions saw the Hoek Brown failure criterion coupled with Bieniawski s Rock Mass Rating RMR system as a means to scale laboratory intact rock properties to those for the jointed rock mass Hoek amp Brown 1988 and improvements to better account for poorer quality rock masses Hoek et al 1992 Further experience with the latter found that it was difficult to apply RMR to
Table 6 5 provides a rating system for the rock mass based on the measured RQD Figure 6 13 presents a rendering of the determination on RQD from a hypothetical section of recovered rock core Table 6 5 Rated quality of rock mass based on RQD Measured RQD Quality 0 to 25 Very Poor 25 to 50 Poor 50 to 75 Fair 75 to 90 Good 114 Measured RQD Quality
one of the basic elements of the two predominant contemporary classification systems of rock masses – the RMR rock mass rating classification and the Q classification 2 ROCK QUALITY DESIGNATION In determining the RQD index only sound core pieces longer than 100 mm are to be considered Figs 1 and 2 Accordingly RQD enables core logging as well as evaluation of
Short on the RMR Rock Mass Rating system This engineering classification system which was developed by Bieniawski in 1973 utilises the following six rock mass parameters 1 Uniaxial compressive strength of intact rock material 2 Rock quality designation RQD 3 Spacing of discontinuities 4 Condition of discontinuities given as
This is determined by the rock mass rating RMR and thus a geological survey is imperative to locate the best site for the cavern 56 57 The last panel in Fig 3b correlates the RMR method
Brown failure criterion for jointed rock masses is defined by 1 where and are the maximum and minimum effective principal stresses at failure is the value of the Hoek Brown constant m for the rock mass s and a are constants which depend upon the rock mass characteristics and is the uniaxial compressive strength of the intact rock pieces a
rock mass rating values there is a decreasing understanding of the reality Quite often more or less sophisticated statistical methods are being applied to the numbers obtained from the field and important observations critical to the understanding of the rock mass behaviour are being averaged in or rejected This
quot rock mass characteristics quot means a numerical index or rating that is derived from a semi quantitative evaluation of rock discontinuities and other inherent qualities used to determine the ground stability in a specific area of an excavation and that classifies the ground based on this evaluation quot rockburst quot means a mining induced seismic event that causes injury to persons or
Empirical design methods such as the Rock Mass Rating System Geomechanics Classification RMR and Q system Classification Q are commonly used for design of under ground structures and are coming into common use for other structures as well If these methods are used the necessary data must be collected during core logging If hazardous waste site characterization
Rock mass properties Introduction Reliable estimates of the strength and deformation characteristics of rock masses are required for almost any form of analysis used for the design of slopes foundations and underground excavations Hoek and Brown 1980a 1980b proposed a method for obtaining estimates of the strength of jointed rock masses based upon an
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