IS 13365-1 (1998): Quantitative classification system of ...

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2 ! $ ' + - Satyanarayan Gangaram Pitroda Invent a New India Using Knowledge 0 1 ' 5 Jawaharlal Nehru Step Out From the Old to the New 1 + , 1 + Mazdoor Kisan Shakti Sangathan The Right to Information, The Right to Live ! > 0 B Bhart hari N ti atakam Knowledge is such a treasure which cannot be stolen Invent a New India Using Knowledge IS 13365-1 (1998): Quantitative classification system ofrock mass - Guidelines, Part 1: RMR for predicting ofengineering properties [CED 48: Rock Mechanics]IS 13365 (Part1 ) : 1998 Reaffirmed 2010 ~~~~~-~ff~'q11J1~~c6~c6~~mnt~(am'tRam)In dianStandardQUANTITATIVECLASSIFICATIONSY STEMSOFROCKMASS GUIDELINESPART 1 ROCK MASS RATING(RMR)FOR PREDICTINGENGINEERING BIS1998 BUREAUOFINDIANSTANDARDSMANAK BHAVAN,9 BAHADURSHAH ZAFAR MARGNEWDELHI110002 July1998 PriceGroup6 13365(pART1).

3 1998 QUANTITATIVECLASSIFICATIONSYSTEMSOFROCKM ASS -GUIDELINESPART1 ROCKMASSRATING(RIIR)FORPREDICTINGENGINEE RINGPROPERTIES(Page4, ) -Substitutethefollowingfortheexistingfig ure:to' +----t-----+---+ ;---~..----+.. +-----+---------t--~~ ~Ie+-----.+ +r---___+_-I2~+--~~+---+ AS (CED48)RepJ'Oll'lPhyUnit,BIS, RockMechanicsSectionalCommittee,CED48 FOREWORDThisIndianStandard(PartI)wasadop tedby theBureauofIndianStandards,afterthedraft finalizedbytheRockMechanicsSectionalComm itteehad beenapprovedby the masses has alsoprovidesa commonbasis is the reason whyquantitativeclassificationshavebecome verypopularalloverthe touncenainresultsbecauseofuncertainities inobtainingthecorrectvalue of inputparametersat 2ofthisstandardpresentsQuantitativeClass ificationSystem,andPart3 theformulationofthisstandardis test oranalysismadeinaccordancewith thisstandard,ifthe finalvalue,observedorcalculated,is to beroundedoff, it shall bedoneinaccordancewith IS 2 : 1960'Rulesforroundingoffnumericalvalues( revised)'.

4 Thenumberofsignificantplacesretainedin theroundedoffvalueshouldbe thesameasthatofthespecifiedvaluein thisstandard. IS13365(Part1 ) : 1998 IndianStandardQUANTITATIVECLASSIFICATION SYSTEMSOFROCKMASS -GUIDELINESPART 1 ROCK MASS RATING(RIA",FORPREDICnNGENGINEERINGPROPE RTIES1 SCOPET hisstandard(Part1)coverstheprocedureford eterminingtheclassofrockmassbasedongeome chanicsclassificationsystemwhichis alsocalledtheRockMass Rating(RMR) ,thestand-uptimeorbridgeactionperiodand thesupportpressuresofanundergroundopenin g,Itcanalsobeusedforselectinga ,cohesion,angleofinternalfrictionandelas ticmodulusoftherockmass can alsobeused , the timeofpublication, ,agivensiteshouldbedividedinto anumberofgeologicalstructuralunitsinsuch a way thateachtypeofrock masspresentinthe area.)

5 A)Uniaxialcompressivestrengthofintactroc kmaterial(IS8764),b) Rockqualitydesignation[IS 11315(part11)],c)Spacingofdiscontinuitie s[IS 11315(Part2)],d)Conditionofdiscontinuiti es[IS 11315(Part4)],e)Groundwatercondition[IS 11315(Part8)]. andt)Orientationofdiscontinuities[IS 1131S(Part1)]. Annex StrengthofIntactRockMaterial(qc)Thestren gthoftheintactrockmaterialshouldbeobtain edfromrockcoresinaccordancewithIS9143or IS8764orIS 10785 (ItemI). (RQD)Rockqualitydesignation(RQD)shouldbe determinedasspecifiedin IS 11315(part11).Thedetailsofratingaregiven inAnnex B(ItemIl),Wheretherockcoresare notavailable,RQDcanbedeterminedwith thehelpoffollowingformula:RQD= forJ;< ,= takenas10evenifitis , ,minorfaults, gi venin Annex B (ItemIII).

6 ConditionofDiscontinuitiesThisparameteri ncludesroughnessofdiscontinuitysurfaces, theirseparation,lengthorcontinuity,weath eringofthe infilli ng(gauge) ng aregiveninAnnexB(ItemIV).Thedescriptiono fthetermusedin theclassificationisgivenin IS 11315(Part4) and IS11315(PartS). IS 13365 (Part1 ) : the case of tunnels, the rateofinflowofgroundwater in litre per minute per10mlength of the tunnelshould bedetermined. or a general condition can bedescribedascompletely dry, damp, wet, dripping, ,these shouldbestated and expressedintermsofthe ratioofthe water pressure to the majorprincipal stress. The latter shouldbeeither measuredfrom thedepthbelow thesurface(verticalstressincreases with depth metreofthedepthbelow surface).

7 Thedetails are given in AnnexB(ItemV).Ratingofabove five parameters( )is added to obtain whatiscalled the basic rockmassrating(RMRbasic). the strike anddip strike should be recordedwith reference to magnetic north. The dip angle istheanglebetweenthehorizontalandthedisc ontinuityplane taken in a direction in which theplane dips. The value of the dip and the strike shouldberecorded as shown in AnnexB(ItemVI)for eachjointsetofparticularimportancethat areunfavourableto the structure. In addition the orientationoftunnelaxis or slope face or foundationalignmentshould the dipofthediscontinuitiesisconsideredwithr espectto theorientationoftunnel axis or slope face or foundationalignment.

8 To facilitate the decision whether the strikeand dip are favourable or not, reference shouldbemade to AnnexC,TablesClandC2whichgiveassessmento fjointfavourability for tunnels and ,adjustmentfororientationofdiscontinuiti esis applied as per Item VII,AnnexBinearlierobtained basic rock mass rating (RMR) The rock mass rating shouldbedeterminedasan algebraicsumof ratings for all theparametersgiven in Items I toVIafteradjustmentsfororientationofdisc ontinuitiesgiveninitemvnofAnnexB. ThesumofItems II to V is called Rock Condition Rating(RCR)which discounts the effectofcompressivestrengthofintact rock material is also called as the ,therock massshouldbeclassifiedas very good (rating100-81).

9 Good(80-61),fair(60-41),poor (40-21) and very poor 20) alsobeobtained asfollows:RCR=8In( )+ been namedasrock mass number ,theuncertainitiesinobtainingcorrectrati ngofSRFiseliminatedasexplainedbelow:Q=(R QDIJn)(JrlJa)(JwISRF)orN= (RQDIJn)(JrlJa)JwIt canbeseenin above equation thatNis free fromSRF. RQD, In, ,andJwareparametersasdefinedin IS13365(Part2). the case of larger tunnels andcaverns,RMRmaybesomewhatless thanobtainedfromdrifts. In drifts, one may beobtainedfordifferentorientationoftunne ls after taking intoaccounttheorientationoftunnel axis with respect tothecriticaljointset (ItemVI,AnnexB). , theundamagedface shouldbeused toestimatethe valueofRMR,sincetheoverallaimis todeterminethepropertiesoftheundisturbed rock mass.

10 Severe Theengineeringpropertiesofrock masses canbeobtainedfrom thisclassificationasgiven inTable1based on assumptions given in to rock mass rating lies within a given range, stand-up time dependsuponeffectivespanoftheopening which is definedassizeoftheopeningorthe distance between tunnel face and theadjoiningtunnel support,whicheverisminimum( ).For archedopeningsthestand-uptime wouldbesignificantly higher than that for blasting will furtherincreasethestand-uptime as damage to the rock mass that a rock mass behaves as aCoulombmaterial,itsshear strength willdependuponcohesionand angleofinternal friction. Usuallythestrengthparametersare different forpeakfailure and valuesofcohesionfor dry rock massesofslopesare likely Forundergroundopenings,the valuesofcohesion willstillbehigher( and ).