K.N. Toosi university of Technology 11/26/2015 Dr. Hasan Ghasemzadeh

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1 ROCK MECHANICS Rock cassification Goodman cassification(1980) Crystaine texture Castic texture Very fine-grained rock Organic rock Hasan Ghasemzadeh ٤ Rock cassification Goodman cassification(1980) Terzaghi cassification Goodman cassification Tota/Soid Core Recovery(TCR/SCR) Rock Quaity Designation (RQD) Rock Structure Rating (RSR) Rock Mass Rating (RMR) Tunneing Rock Quaity Index (Q) Crystaine texture Doomite ٢ ٥ Terzaghi cassification (1946) Goodman cassification(1980) Intact rock Stratified rock Moderatey jointed rock Bocky & seamy rock Crushed rock Squeezing rock Sweing rock Crystaine texture Gneiss ٣ ٦ Dr. Hasan Ghasemzadeh 1

2 Goodman cassification(1980) Very fine-grained rock Goodman cassification(1980) Organic rock Basat Coa ٧ ١٠ Goodman cassification(1980) Tota Core Recovery(TCR) Very fine-grained rock Interbeds Basat Breccia Sate TCR sum of pieces tot core run 100% ٨ ١١ Goodman cassification(1980) Soid Core Recovery(SCR) Very fine-grained rock Vesicuar Basat SCR sum of soid core pieces tot core run 100% ٩ ١٢ Dr. Hasan Ghasemzadeh 2

3 Rock Quaity Designation (RQD) RQD Basat interiors RQD sum of core pieces >10cm ength tot core run 100% ١٣ ١٦ Rock Quaity Designation (RQD) tota core ength=200 RQD sum of core pieces >10cm ength tot core run مثال 100% Rock Structure Rating (RSR) نوع و سختي سنگ و ساختار زمين شناسي فاصله و جهت درزه ها جريان ا ب RQD 100% 55% 200 Deere (1989) ١٤ ١٧ Rock Quaity Designation (RQD) RQD= {(core onger than 100mm)/(tota core ength mm)}*100 Rock quaity RQD Very poor 0-25 Poor Fair Good Exceent جهت درزه آزيموت و شيب را ميتوان با استفاده از قطب نما و شيب سنج اندازه گرفت Azimuth=dip direction معمولا بين صفر تا 180 درجه بيان مي شود strike 90 (180) Strike ١٥ ١٨ Dr. Hasan Ghasemzadeh 3

4 Rock Structure Rating (RSR) Vickham et a. (1972) RSR=A+B+C=<100 A : Genera geoogy Bieniawski ( ) Rock Mass Rating (RMR) Geomechanics cassification Numerous amendments since 1976 For assessing the stabiity of rock sopes strength of the intact rock RQD Groundwater Discontinuities Spacing, ength, roughness Aperture width, infi, weathering RMR=A1+A2+A3+(A4 or E)+A5+B=<100 ١٩ ٢٢ Rock Structure Rating (RSR) ROCK MASS RATING (RMR) B : oint pattern Bieniawski (1989) ٢٠ ٢٣ Rock Structure Rating (RSR) ROCK MASS RATING (RMR) C : Ground water, joint condition Bieniawski (1989) Gpm=3.785 iter per minute ٢١ ٢٤ Dr. Hasan Ghasemzadeh 4

5 Bieniawski (1989) ROCK MASS RATING (RMR) Evauation of Tunnes based on RMR ٢٥ Exampe: 10 m span RMR = 80 Stand up time > 4 years RMR = 50 Stand up time 2 days ٢٨ Rock Mass Rating (RMR) (Rock tunneing quaity index) Initia data base was 212 cases of nominay unined tunnes and caverns 50 rock types were initiay represented Numerous shear zones and fauts containing cay Numerous shear zones and fauts containing cay A arger number of igneous and metamorphic rocks ٢٦ ٢٩ RMR for sopes or tunnes (Rock tunneing quaity index) Additiona factors appied to RMR basic : Accounts for excavation method Accounts for joint orientation Stand up time for various tunne spans based on RMR Modified RMR for Mining -MRMR (Laubscher) -MBR (Cummings et a) طبقه بندي اصلاح شده RMR جهت در نظر گرفتن تنش برجا و تنش هاي ايجاد شده در اثر حفاري و همچنين در نظر گرفتن تاثيرات انفجار و هوازدگي Q bock size RQD n frictiona r a w Q 2000 Active stress and water effect ٢٧ ٣٠ Dr. Hasan Ghasemzadeh 5

6 (Rock tunneing quaity index) Q RQD n structure of the rock mass RQD Rock quaity designation (10-100) n = joint set number (0.5 20) The ratio RQD/n bock size r a w Q 1000 n ٣١ ٣٤ ٣٢ ٣٥ RQD n Very poor 0-25 Poor Fair Good Exceent One joint set 2 Two joint sets 4 Two joint set + 6 random Three joint sets 9 Q RQD r w n a roughness and frictiona characteristics r = joint roughness number (0.5-5) a = the joint ateration number ( : hard to soft fiing) The ratio r / a joint roughness & friction ٣٣ ٣٦ Dr. Hasan Ghasemzadeh 6

7 r a ٣٧ ٤٠ r a ٣٨ ٤١ r a ٣٩ ٤٢ Dr. Hasan Ghasemzadeh 7

8 r / a ٤٣ ٤٦ r / a w ٤٤ ٤٧ Q RQD n r a w w Active stress w = joint water reduction factor (1 0.05: dry to water under pressure) = the stress reduction factor ( : ow stress & favourabe orientation to high stress) ٤٥ ٤٨ Dr. Hasan Ghasemzadeh 8

9 w ٤٩ ٥٢ ٥٠ ٥٣ ٥١ ٥٤ Dr. Hasan Ghasemzadeh 9

10 2000) ٥٥ ٥٨ ٥٦ ٥٩ ٥٧ ٦٠ Dr. Hasan Ghasemzadeh 10

11 Exampe NGI system GSI ٦١ Dr. Hasan Ghasemzadeh Exampe NGI system GSI ٦٢ Dr. Hasan Ghasemzadeh Q RMR comparison Exampe ٦٣ ٦٦ Dr. Hasan Ghasemzadeh 11

12 Q RMR comparison Tunnes and the Q rating Require ESR and D e D e = equivaent dimension Excavation span or height D e ESR ESR = excavation support ratio ESR is a function of the tunne use and acceptabe eve of risk ٦٧ ٧٠ Q RMR comparison ESR Vaues (Barton et a 1974) Temporary mine openings 3-5 Permanent mine openings, water tunnes for hydro power, etc Power stations, major road & raiway tunnes, etc. 1 Underground nucear power stations, raiway stations, etc. 0.8 ٦٨ ٧١ Q RMR comparison Tunnes and the Q rating ٦٩ ٧٢ Dr. Hasan Ghasemzadeh 12

13 Tunnes and the Q rating Evauation of Tunnes based on Q rating Exampe: 10 m span & ESR = 2 Q= 40 Requires rock bots at 3 m spacing, 2.4 m ong 10 m span & ESR = 1 Q= 40 Requires rock bots at 3 m spacing, 3 m ong ٧٣ ٧٦ Evauation of Tunnes based on Q rating Rock Bots- Exampe: 1) 10 m span & ESR = 2 Q= 40 CT Bots 2) 10 m span & ESR = 1 Q= 40 Rock bot engths are for an ESR of 1.0 (conservative) ٧٤ ٧٧ Tunnes and the Q rating Tunnes based on Q rating Fina Exampe: 10 m span & ESR = 1 Q= 10 Requires rock bots at 2.3 m spacing, 3 m ong in 40 mm shotcrete Exampe: 10 m span ESR = 2 10 m span ESR = 1 Q= 40 Q= 40 ٧٥ ٧٨ Dr. Hasan Ghasemzadeh 13

14 Exampe: 10 m span ESR = 1 Tunnes and the Q rating Q= 10 Rock Bots- Lengths (L) can be stimated based on the excavation span (B) : L = ( B) / ESR maximum unsupported span can be estimated from: B max = 2 (ESR) (Q) 0.4 reationship between the vaue of Q and the permanent roof support pressure (P roof ) (Grimstad and Barton,1993) ٧٩ ٨٢ Stand-up Time Histogram ٨٠ ٨٣ Note Histogram basting damage wi resut in the creation of new joints, can be accounted for by reducing the RQD vaue for the bast damaged zone (Loset, 1992) it is appropriate to give a range of vaues to each parameter in a rock mass cassification and to evauate the significance of the fina resut. ٨١ ٨٤ Dr. Hasan Ghasemzadeh 14

15 Histogram ٨٥ KEY POINTS Rock mass rating systems are a usefu way of forming an evauation of rock masses The Q or NGI system was based on tunneing The RMR (CSIR) system is more commony used for sope stabiity The strength of rock masses can be judged from these sytems ٨٦ Dr. Hasan Ghasemzadeh 15