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• WHEXSIopeEvaluation Adrian6rown <br />Table 6. Rock Mass Rating System (Bieniawski, 1989) <br /> <br />• <br />A CLASSIFICATION PARAMETE RS AND THEIR RATINGS <br />Parameter Ran a of values <br /> Point-load <br />Strength siren index <br />cf 9~ <br />>70 MPa <br />4 -10 MPa <br />2 - 4 MPa <br />1 - 2 MPa For this low range - <br />uniexlal compressive <br />test is referred <br />1 Intact rock Unlaxial comp. <br />matelot stren >250 MPa 100 - 250 MPa 50 -100 MPa 25.50 MPa 5 - 25 <br />MPa 1 - 5 <br />MPa < 1 <br />MPa <br /> Rating 15 12 7 4 2 1 0 <br /> Drill core Quality RQD 80% -100% 75% • 90% 50% - 75% 25% - 50% < 25% <br />2 Rating 20 17 13 8 3 <br /> Sparing of discontlnultles > 2 m 0.8 - 2 . m 200 - 800 mm 60 - 200 mm < 80 mm <br />3 Rating 20 15 10 8 5 <br /> <br /> <br />4 <br /> <br />Condition of dlscontlnulfles <br />See E) <br />( Very rouggh surfaces <br />Nat r"ntlnuous <br />No separetlon <br />Unweathered well <br />rock SI g tly rough <br />surfaces <br />Separation < 1 mm <br />SAghtly weathered <br />wells SUghtly rough <br />surfaces <br />Separation < 1 mm <br />Higghl weathered <br />wetlsy Slickensided surtaces <br />or <br />Gouge < 5 mm thick <br />or <br />Separation 1-5 mm <br />Continuous Soft gouge >5 mm <br />thick <br />or <br />Separation > 5 mm <br />Contlnuous <br /> Rating 30 25 20 10 0 <br /> Inflow per 10 m <br />tunnellen um None < 10 10 - 25 25 -125 > 125 <br /> <br />5 Ground <br />water (Joint water press)/ <br />(Ma or prindpal a) 0 < 0.1 0.1, - 0.2 0.2 - 0.5 > 0.5 <br /> Generelconditlons Completatydry Damp Wet Dripping Flowing <br /> Raring 15 10 7 4 0 <br />B. RATING ADJUSTMENT FOR DISCONTINUITY ORIENTATIONS (See F) <br />SUike and dip orienhatlons Very favourable Fevourebie Fair Unfavoureble Very Unfavourable <br /> Tunnels & mines 0 -2 -5 -10 -12 <br />Ratings Foundations 0 -2 -7 -15 -25 <br /> Slopes 0 -5 •25 -50 <br />C. ROCK MASS CLASSES DETERMMED FROM TOTAL RATINGS <br />Ratlng t00 t- 81 80 t- 61 80 t- 41 40 r 21 < 21 <br />Class number 1 II III N V <br />Description Very good rbdc Good rock Fair rods Poor rods Very poor rock <br />D. MEANING OF ROCK CLASSES <br />Class number I II III N V <br />Averagestand-up time 20 yrs for 15 m span 1 year for 10 m span 1 weak tar 5 m span 10 hrs for 2.5 m span 30 min for 1 m span <br />Cohen on of rock mass (kPa) > 400 300 - 400 200 -300 100 - 200 < 100 <br />Fddion angle of rods mass (deg) > 45 35 - 45 25.35 15 - 25 < 15 <br />_ E. GUIDELINES FOR CLASSIFICATION OF DISCONTINUITY conditions <br />Otscontlnulty length (persistence) <br />Radn < 1 m <br />6 1- 3 m <br />4 3 -10 m <br />2 10 - 20 m <br />1 > 20 m <br />0 <br />Separetlon (aperture) <br />Ratio r None <br />6 < 0.1 mm <br />5 0.1-1.0 mm <br />4 1 - 5 mm <br />1 > 5 mm <br />0 <br />Roughness <br />Rahn Vety rough <br />6 Rough <br />5 Slightly rough <br />3 Smoolh <br />1 Sllckenslded <br />0 <br />IMllling (gouge) <br />Rath None <br />8 Hard filling < 5 mm <br />4 Hard filling > 5 mm <br />2 Soft filling < 5 mm <br />2 Soft filling > 5 mm <br />0 <br />Weathering <br />Ratings Unweathered <br />6 SIIghUy weathered <br />5 Moderetelq <br />wee 3ered Highly weathered <br />1 Decomposed <br />0 <br />Report 1385L..200309017 11 <br />