4thIntSympRollerCompConcr 2003 DMR NovaClassificaçãoRMRparaFundaçõesBarragens Romana

8/9/2019 4thIntSympRollerCompConcr 2003 DMR NovaClassificaoRMRparaFundaesBarragens Romana

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Preprint for the 4thInternational Symposium on Roller Compacted Concrete (RCC) Dams MADRID 2003

Manuel Romana July 2003 1

DMR , a new geomechanics classification for use in damsfoundations, adapted from RMR

Manuel Romana

Universidad Politcnica de Valencia, [email protected]

ABSTRACT: Some topics, which difficult the effective use of RMR for dam foundations, are reviewedand a new geomechanics classification system, DMR (Dam Mass Rating), is proposed -as an adaptation

of RMR- giving tentative guidelines for several practical aspects in dam engineering and appraisal ofdam foundations (overall stability, needed excavation/treatment, relative deformation modulusdam/foundation) taking account of the effects of rock mass anisotropy and of the water saturation. Theformulae for estimation of the rock mass deformation modulus Emare discussed.

1 INTRODUCTION

A large dam is, almost always, a unique work,adapted to the morphology and the strength of thefoundation, and also to the hydrological regime ofthe river. The dam, and the impounded water,

interact with a great mass of terrain, very faraway sometimes from the dam itself. The designand construction of a dam, are complex andcasuistic, difficult to standardize. Neverthelessdams are classified and there is a taxonomy ofthe different dam classes. It is usual, whendesigning a dam, to refer it to precedents ofsimilar dams in similar terrains. Needs of terrainstrength and deformability quantification arequite different for each type of dam: arch, gravity(CVC or RCC), CFRD, rockfill, earth As a ruleof thumb concrete dams (and the face of CFRD)require rock foundations whereas fill dams can befounded in soil.

Anyway it is widely accepted as good practiceto fix the most important properties of a damfoundation referring them to some quality index(i.e. seismic velocity of P-wakes, weatheringdegree). These properties are mainly

permeability (frequently expressed in Lugeonunits), shear strength of the foundation (mass

cohesion and friction in most cases), and terraindeformability. The dam must retain water, haveenough safety against sliding and adjust itself to

the terrain deformations without too muchcracking in service.

Therefore it is very convenient to arrange thequantitative data obtained from geologic-geotecnic field investigation attending to some

previous idea about the importance of each one inface of dam design, construction and operation.And this is the concept which informs thegeomechanics classifications. A very interesting

precedent is the so called Engevixpreclassification used in Itaip to cope with theenormous amount of geotechnic data for thefoundation of the long lateral wing dykes of themain dam. It was developed by Cruz (1976) andcan be reviewed in Camargo et al (1978) andJohn (1978). Basically it is a rating system for the

different properties of the rock mass attending totheir effects in the dam foundation safety. Otherinteresting precedent is the Kikuchi (1979)classification, very well adapted to thegeologically young volcanic terrains which

prevail in Japan.The RMR geomechanics classification was

originally proposed by Bieniawski (1973) for usein tunnels, slopes and foundations. In fact the useof RMR has been very diverse: extremelyfrequent in underground works, very scarce in

slopes and almost nil in dam foundations. Thereis only a seminal paper (by Bieniawski and Orr,1976), no chapter on dams in the BieniawskiJubilee Volume and very few application papers,


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Preprint for the 4thInernational Symposium on Roller Compacted Concrete (RCC) Dams MADRID 2003

except in only an important topic: estimation ofthe rock mass deformation modulus Em. Severalauthors have referred to the use of RMR as auseful tool for the description of rock massfoundations (Di Salvo, 1982; Van Schalkwyk,

1982; Snchez Sudon and Maueco, 1991;Marcello et al, 1991; Hemmen, 2002). Pircher(1982) said the future seems to be in thedevelopment of quality index values e.g. RMR byBieniawski and Serafim (1988) stated thatappropriate rock mass classifications can beused to obtain a good estimate of (shear strengthand deformability) parameters, both in GeneralReports for Congresses on Large Dams.

2 DIFFICULTIES IN RMR USE FOR DAMS

Difficulties in RMR use for dam foundationsderive from several points: consideration of thewater pressure is very doubtful (the pore pressureratio varies along the dam foundation, dams mustoperate with changing water levels), there areno good rules for quantifying the adjusting factorfor the joint orientation (which ideally shouldallow for the safety against total failure byhorizontal shear, for local failure, for waterleakage through the joints), there are changesin properties of both the rock, the rock mass andthe joints induced by watering changes(saturation ,desiccation, flow along the joints).

General stability against horizontal sliding isnot a very common problem (although there have

been failures as in Malpasset). The dam engineerneeds, when comparing possible dam sites, rapidappraisals of several topics: general adequacy ofsite for each type of dam, depth of excavation ofaltered rock (if needed), required amount of

foundation treatment (grouting). So, there cannotbe only an adjusting factor and a sole guideline.Besides conditions will be different according thetype of dam.

An appraisal of the deformability of the rockmass is needed in order to calculate stresses,strains and deformations in dams. Hence,empirical correlations between geomechanicsclassifications and deformation modulus of therock mass Em have always been very popular.The first one of these correlations was proposed

by Bieniawski (1978), and afterwards severalauthors have introduced modifications to improve

it.Most of these correlations fail to consider twovery important aspects: anisotropy of rock massand water effect.

3 INFLUENCE OF WATER ON BASIC RMR

It is common to define a basic RMRBindependent of the work which is going to the

built, as the addition of the five RMR parameters,without any adjusting factor. The fifth parameter,WR, is related to water, with a weight on RMRBup to 15 points (15% of the maximal total).

The best method to determine the effect ofwater on this parameter is the use of the water

pressure ratio ru = u/v were u is the waterpressure and vthe total vertical stress. The waterrating WR can be approximated by the formulaWR = 10log (1/ru) 1.5 (valid for 0.02 < ru< 0,7)to apply in RMR determination of the rating forthe fifth parameter WR (see Table 1).

Table 1 Relationship between (WR) and ruWR 15 10 7 4 0ru(1) 0 0-0.1 0.1-0.2 0.2-0.5 > 0.5ru(2) 0-0.2 0.07 0.14 0.28 0.7(1) Bieniawski (2) formula

Around the dam ru changes in every pointdepending on the valley geometry, the waterlevel, and the efficiency of the grouting curtains(if exist). Therefore it would be necessary a three-dimensional flow model of the dam and thesurrounding terrain to determine the ru exactvalues. Anyway ru>0.4 for almost all theupstream points, so the WR parameter will getvalues of less than 2.5.

Furthermore the compressive strength of the

rock will diminish heavily when saturated and itsrating probably will halve. So a very crude wayof taking account of the water effect on Emwould

be to subtract around 20 points of the dryvalues of RMR.

If we accept the Serafim-Pereira formula (seelater) for determination of Emfrom RMR

Em(Gpa) = 10(RMR-10)/40

the value of Em (dry) would be approximatelythree times the value of Em (saturated), for 10 j)

CF=(1-sin (j -d))2 (j>d)where dis the direction upstream-downstream ofthe dam axis and j is the dip direction of thesignificative joint.

DMRSTA = RMRBD + CF x RSTAwhere RMRBD(basic dry RMR) is the additionof the RMR five parameters and RSTA is theadjusting factor for dam stability (Table 3).

Actually there are no data allowing toestablish a correlation between the value of

DMRSTA and the degree of safety of the damagainst sliding. As a rule of thumb we cansuggest:

DMRSTA> 60 No primary concern60 > DMRSTA>30 Concern30 > DMRSTA Serious concern

but these cannot be taken as numerical statementsbut only as danger signals for the designer. Damstability must always and in any case be checked

by the designer taking account of the probabledistribution of water pore pressure across the dam

foundation and of the mobilized shear strength ofthe significative joints. About this question the



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Spanish National Committee on Large Damsstates that The study of the dam safety againstsliding requires a knowledge of the strength ofthe rock mass. The simple correlations betweengeomechanics classifications and rock mass

strength are not well established for damfoundations (SCOLD, 1999).

5 GUIDELINES FOR EXCAVATION ANDCONSOLIDATION GROUTING OF DAMFOUNDATIONS

The most usual requirement for the quality of therock foundation for a concrete dam wassomething as good quality, sound rock, fresh,not weathered. Sharma (1998) is more specific

demanding that the entire (foundation) areashould be stripped to firm rock capable ofwithstanding the loads. Any layer of weak or softmaterial has to be excavated and replaced withconcrete. He prescribes dental concretetreatment filling with concrete any open, (or filledwith soft fill), joint according USBR rules.

In most cases the foundation is excavated untilclass II rock in the central part of the valley(where the dam is higher) and until class II-IIIrock in the abutments. Spillways are founded, if

possible, in class I rock. The most frequentparameter to be quantified in order to check therock quality was the celerity of P-waves,measured by geophysical methods. Actually mostrock masses are investigated and described withthe ISRM suggested methods, which allow for aquick classification work.

It is desirable to gather data on the RMR valueof dam foundations and this author is working inthat. Actually some simple guidelines can be

tentatively proposed (Table 4) for excavation andfor consolidation grouting a few meters deep.

Table 4 Tentative guidelines for dam foundation excavationand consolidation grouting (Romana, 2003)

CONSOLIDATION GROUTINGACCORDING RMRBD

TIPE OFDAM

EXCAVATETO RMR+BD Systematic Spot None

EARTH - - - -ROCKFILL >20 (> 30) 20-30 30-50 >50GRAVITY >40 (> 60) 40-50 50-60 >60

ARCH >50 (> 70) 50-60 60-70 >70(+)minimum (desirable)

-gravity dams included CVC and RCC concrete-rockfill dams included are the ones sensible tosettlement (like CFRD and AFRD)

6 CORRELATION BETWEEN EMAND RMR

6.1 General

Em modulus can have very different valuesdepending on the direction of the principal stress.In stratified rock mass, and/or with a governing

joint orientation, the equivalent elastic modulus ofdeformation is the weighted arithmetic mean ofthe deformation modulus of the strata (when thestress is parallel to them), and the weightedharmonic mean (when the stress is perpendicularto them). Therefore the perpendicular deformationmodulus is always the minimal one and the

parallel deformation modulus is always the

maximal one. The difference between both ofthem gets wider as anisotropy of the rock massincreases. Barton (1983) proposed the followingformulae: Emin= 0.4 Emean Emax= 1.6 Emeanand therefore (Emax - Emin) / Emean= 1.2

This implies a relationship of 4 betweenmaximal and minimal values of deformationmodulus, which, according to Barton, isconfirmed by other data published by Rocha(1964) and Bieniawski (1978), and is probablyadequate for rock masses very anisotropic and/or

very bedded. In homogeneous rock masses, therelationship between maximal and minimal valuesof the deformation modulus is smaller. Manyauthors have published data gathered from in situtests (Table 5). In all cases the RMR value to beapplied is the basic one without the adjustingfactor for the joints orientation proposed byBieniawski for foundations. However, thevariation of the modulus value according todirection of the principal stress suggests that itwould be useful to apply some adjusting factor.

Table 5. Some data from in situ tests on relation Emax/ Emin

SITE ROCKMASS Emax/Emin REFERENCE

Colbun plant Andesite 1,4 Van Sint (1993)

Marl 1,3Ridracolidam Sandstone 1,4

Oberti et al(1986)

Sandstone 1,3Tamzaourtdam Siltstone 1,9

Jaoui et al(1982)

Manuel Romana July 2003


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Water also reduces both the strength and theequivalent deformation modulus when the rockmass is saturated, a very important effect in damfoundations. The first papers neglected this watereffect. The introduction of GSI included a very

simple way to consider the water effect: toevaluate RMR as if the rock mass were fully dryand to introduce water pore pressure incomputations (see Bieniawski 2000). But thatdoesnt take account of the reduction of strengthand deformability of the rock when saturated.Figure 1 (Pells, 1993) shows a Deere-Millerdiagram containing data from compression tests(failure strength and deformation modulus at 50%of failure strength) in dry and saturatedHawkesbury sandstone. Saturation implies a

reduction almost proportional in both parameters,but the relationship between them would remainapproximately constant.

Figure 1. Strength and modulus data on HawkesburySandstone (Pells, 1993)

6.2Proposed correlations between EMand RMR

Bieniawski (1978) proposed the correlationEm(GPa) = 2 RMR 100

and it can be seen (fig. 2a) that this formula maybe adequate for RMR > 65, has a wide scatteringfor 55 < RMR < 65, (a very common interval in

practice) and cannot be used for RMR < 55.

Bieniawski recommends good engineeringjudgment when using his formula.

Bieniawski correlation has been modified bySerafim & Pereira (1983) for all values of RMR

Em(GPa) = 10(RMR-10) / 40 (fig. 2a,2b)

a formula that has been widely accepted. Thisformula works better for RMR > 34. There were

only three cases with lower RMR (22, 30 and 33)in their data bank, and the correlation was worsein all three of them.. Figure 2 shows bothBieniawski and Serafim & Pereira correlations. In

practice most of engineers follow proceduressimilar to the guidelines of USA Federal EnergyRegulatory Commission (1999): for RMR > 58use Bieniawski formula; for RMR < 58 useSerafim-Pereira one. The RMR=58 valueappears to have been selected because it is theabscissa of the intersection between both curves.

(a)

(b)Figure 2. Correlations between the in-situmodulus

of deformation and RMR according to:(a) Bieniawski (1978) and (b) Serafim& Pereira (1983)

Hoek and Brown (1997) proposed a

modification of Serafim & Pereira formula in



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order to take account of the influence of rockcompressive strength c(MPa):

Em (Gpa) = (c / 100)1/2x 10 (GSI 10) / 40

This formula is proposed for all values of RMR.The Serafim & Pereira original value would

correspond to rocks of 100 MPa compressivestrength, which is not usual in the rock massesstudied by Serafim & Pereira, with RMR < 50.This modification by Hoek & Brown could beuseful for high values of RMR and allows for thewater effect testing dry and saturated probes.Hoek notes that this equation appears to workreasonably well in those cases where it has beenapplied. However, as more field evidence isgathered, it could be necessary to modify thisrelationship. In fact there are no data supportingthe use of this modification for rock masses ofmedium or low hardness.

In a paper for the 2002 NARMS, Hoek,Carranza-Torres and Corkum have introduced anadditional disturbance factor DEm(GPa)=(1-D/2)x(c/ 100)

x10(GSI 10)/40

The new factor D allows for the effects ofblast damage and stress relaxation, and can beestimated according guidelines given for tunnels,slopes, and pit-quarries, but not for dams. As

excavations for dams foundations are, as a rule,very careful, D should be very low, but it cannotbe 0 because of decompression. Tentativeguidelines (Romana 2003) are as follows:

-Good rock mass, normal blasting D= 0,4-Any rock mass, controlled blasting D= 0,2-Poor rock mass, mechanical excava. D= 0,2

6.3Recommended formulae

With the published data there is only actual basis

for the following recommendations:-RMRBD> 60 Use Bieniawski formula-60 > RMRBD> 35 Use Serafim & Pereira

original formula.-35> RMRBD No formula is sure. Use as a

guess Serafim & Pereira oneThere are no data supporting normalized Hoek

variations of Serafim & Pereira formula. Theresults obtained when applied to good-mediumquality rock masses (e.g. RMR class II-III) withmedium hard rocks (e.g. c =50 MPa) are not

consistent with the published data on Em.

6.4Effect of anisotropy on Em

Em depends on the anisotropy of the rock massand the maximum stress direction. It is possibleto take account of this effect with the following

rules of thumb.In very anisotropic rock masses Emax/Emin = 4.

You can add 8 to RMRB to obtain Emax andsubtract 16 to RMRBto obtain Emin.

In slightly anisotropic rock masses Emax/Emin isin the order of 1.4. You can add 2 to RMRB toobtain Emaxand subtract 1.4 to obtain Emin.

Such values are only approximate but can beuseful when making sensitivity analysis of dam foundation stress fields to get something similarto extreme situations.

The best solution would be to apply aqcorrection factor. Depending on the orientation ofthe joints which define the more competentstrata in the rock mass

6.5Effect of water on Em

The effect of water on Em has been alreadydiscussed. There are no published data and mostof authors used the same value of Embefore andafter impounding the dam. The most frequentlyused WR (water rating) were 7 and/or 10reflecting a certain aim for compromise betweenWR = 15 (dry, ru = 0) and WR = 0 (fullysaturated, ru> 0.5). The above proposed rule ofthumb (to subtract 10 from RMRB to get Emsaturated, when using Serafim & Pereira formula)is only a guess.

7 INFLUENCE OF THE FOUNDATIONDEFORMABILITY ON THE DAM BEHAVIOR

7.1 General

There is a general agreement between damengineers on the fact that two cases are dangerousfor the normal behavior of a concrete dam: if Emvaries widely across dam foundation, or if Ec/Emreaches certain values (Ecbeing the deformationmodulus of concrete). Rocha (1964) establishedthe most followed rule for arch dams (Table 6) ina paper which has become a classic reference

for dam designers.



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Table 6 Effect of Ec/Em on arch dambehavior(Rocha, 1964)

Ec/EmInfluence ondam

Problems

< 11-44-88-16> 16

Negligible

LowimportanceImportantVery importantSpecialmeasures

NoneNoneSomeSeriousVerydangerous

Ec/Em < 4 allows for an easy behavior (andhigh cost tests in foundation could be dispensedwith according Oliveira, 1990). The minimal sure(but with problems) value of Emfor an arch damwould be around 5 GPa. The reported cases ofarch dams founded in rock masses with Em 16 would get to moderate to big

problems. The existence of joints in concretedams helps to cope with relative deformability

problems. This may be the main reason in the

changes in the design of RCC concrete dams,from the first dams with almost no joints to theactual standards. Nevertheless RCC concretegravity dams are less prone to problems thanCVC concrete dams due to the lesser value of Ec.

7.2 Value of Ecin CVC and RCC concrete

Andriolo (1995) gave a detailed report comparingproperties of CVC and RCC. Fig. 3 shows thedata on Ecfrom 5 CVC dams and 13 RCC dams.

The mean data gives relations of:ERCC= 0.40 ECVC at 7 -28 daysERCC= 0.55 ECVC at 90 days

At 90 days ECVCvaries between 28 Gpa and 51Gpa with a mean value of 39 Gpa, whereas ERCCvaries between 11 GPa and 32 GPa with a meanvalue of 22 GPa.

There is a great variation, depending on thecementitious material content, but we can assumefor CVC ECVC = 30/36 GPa and for RCCERCC= 20 GPa (less in many cases).

Fig. 3. Modulus of elasticity values from RCCand CVC

concrete in dams (Andriolo,1995)

7.3 Guidelines for DMRDEF

Zeballos and Soriano (1993) have published theresults of Zeballos Ph. D. thesis (PolytechnicUniversity of Madrid), an extensive and intensivestudy on the effects of Ec/Emvalue on gravity andarch dams Table 7 (gathered using their data)shows the different ranges of RMRDEF related tothe different ranges of possible problems in thedam due to the differences of deformability

between the dam and his foundation.DMRDEF(RMR related to deformability by the

Serafim & Pereira formula)) depends on Em(when the rock mass is saturated) and can beestimated with WR = 5 (a mean value whichcorrespond to a nominal mean value of ru= 0.25)

Table 7. Deformability problems in concretedams according value of DMRDEF (Romana2003)DAMEc

(GPa)

HEIGHT(m)

Normal Problems Seriousproblems

Arch36 GPa

< 100100-150150-200

>50>65>75

40-5050-6560-75

60

25-4040-5050-60

45>55

20-3535-4545-55


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8 FINAL REMARKS

The author wish to express his gratitude to theconsulting engineer Emilio Benitez, who hashelped him to understand the concepts of RCC

concrete dams and provided him with a lot ofbibliographic information.

This paper presents the first result of a ongoingresearch. The author will be grateful to anycontribution with data which confirm, or deny,these preliminary results [email protected]

9 REFERENCES

ANDRIOLO F.R. (1995) RCC properties. Proc.Int. Symp. on Roller Compacted Concrete Dams.

Santander Ed. IECA-CNEGP. Pp 3-26.BARTON N. (1983) Application of Q-Systemand index test to estimate shear strength anddeformability of rock masses. Int. SympEngineering Geology and UndergroundConstruction. Lisbon. Theme II. Panel report.Vol. II, pp II. 51-II. 70.BENITEZ E. (2003) Personal communicationBIENIAWSKI Z.T. (1978) Determining rockmass deformability. Experience from casehistories. Int. J. of Rock Mech and Min. Sci.

Vol. 15 pp 237-242.BIENIAWSKI Z.T. (1979) Tunnel design byrock mass classifications. U.S. Corp of Eng.Technical Report GL-799-19. WES VicksburgMS, pp 55-62 (reference in BIENIAWSKI, 1989,

pp 128-130).BIENIAWSKI Z.T. (1989) Engineering RockMass Classifications. Ed WILEY. New York,252 pp.BIENIAWSKI Z.T.& ORR C.M. (1976). Rapidsite appraisal for dam foundation by

geomechanics classification 12 th ICOLD.Mxico. Q46. R32.CAMARGO P., LEITE C.A., BERTIN NETO S.,MALDONADO F., CRUZ P.T. (1978)Development of conceptual geomechanicsmodels for foundations of concrete dams.Approach applied to three projects. Proc. OfISRM Int. Symp. on rock mechanics related todam foundations. Ed. Kanji M.A. y AbrahaoR.A. Ed. ABMS Pp II-57/II 64.CRUZ P.T. A busca de um metodo mais realista

para analise de macios rocosos como fundaoesde barragens de concreto XI Seminario Nacional

de Grandes Barregens-Fortaleza, Brazil (inportuguese).DI SALVO C.A. (1982) Geomechanicsclassification of the rock mass at SegundaAngostura dam. 14 th ICOLD Rio de Janeiro.

Q53 R30.FEDERAL ENERGY REGULATORYCOMMISSION (1999) Engineering guidelinesfor the evaluation of hydropower projects.Chapter 11- Arch Dams. Washington DC 20426.P 11-18HEMMEN (2002) Paris dam InternetHOEK E. & BROWN E.T. (1997) Practicalestimates of rock mass strength. Int. J. of RockMech. and Min. Sci. Vol. 34, pp 1165-1186.HOEK E., CARRANZA-TORRES E &

CORKUM B. (2002) Hoek-Brown failurecriterium-2002 edition. NARMS. Toronto.ITAIP BINACIONAL (1976) Relatorio n2080-50-5000P-ROA Reference in Camargo etal (1978) (in Portuguese).JAOUI A., ISLAH M:, GARNIER C., GAVARDM. & GILY B. (1982) The Tamzaourt dam. A

buttress dam with particular foundation problems14thICOLD. Rio de Janeiro. Q 53, R 2.JOHN K. (1978) General Report onCharacterization, properties and classifications ofrock masses for dam foundations Proc. of ISRMInt. Symp. on rock mechanics related to damfoundations. Ed. Kanji M.A. y Abrahao R.A. Ed.ABMS. Pp II-1/II-12.MARCELLO A., EUSEPI G, OLIVERO S, DIBACCO R. (1991) Ravanasella dam on difficultfoundation 17 th ICOLD. Vienna Q 66 R 21.OBERTI G., BAVESTRALLO F., ROSSI P. &FLAMIGNI F. (1986) Rock Mechanicinvestigation, design and construction of the

Ridracoli dam .Rock Mechanics and RockEngineering XIX, 3, July-September, pp 113-142.OLIVEIRA R. (1990) Probabilistic approach tothe assessment of foundation properties. Proc.Int. Workshop on arch dams. Coimbra (1987). Ed.Balkema. Pp 314-319.PELLS P.J. (1993) Uniaxial strength testing inComprehensive rock engineering. Ed. J.Hudson. Ed. PERGAMON. Vol. 3, p. 75.PIRCHER W. (1982) Influence of geology andgeotechnics on the design of dams. 14 th ICOLD

Ro de Janeiro Q53 GR.

mailto:[email protected]:[email protected]


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ROCHA M. (1964) Statement of the physicalproblem of the arch dam. Symp. On Theory ofarch dams. Southampton.ROCHA M. (1976) Algunos problemas relativosa Mecnica das Rochas dos materiais de baixa

resistencia Geotecnia. Revista de SociedadePortuguesa de Geotecnia. Novembro-Dezembro.Pp 3-27 (in portuguese).ROMANA M (2002) Determination ofdeformation modulus of rock masses by means ofgeomechanics classifications. EUROCKSymposium (Madeira island) Ed. SociedadePortuguesa de Geotecnia.ROMANA M. (2003) DMR (Dam Mass Rating).An adaptation of RMR geomechanicsclassification for use in dam foundation. Inst.

Cong. on Rock Mechanics. (Technology roadmapfor rock mechanics) South African Inst. Of Minand Met.SNCHEZ SUDON J.F. & MAUECO M.G.(1995) The Cenza Dam Proc. Int. Symp. onRoller Compacted concrete dams. Santander. Ed.IECA-CNEGP. Pp 625-636.SERAFIM J.L. & PEREIRA J.P. (1983)Considerations on the GeomechanicalClassification of Bieniawski. Int. Symp.Engineering Geology and UndergroundConstruction. Lisbon. Theme II. Vol. 1, pp II.33 II.42.SERAFIM J.L. (1988) General Report on newdevelopments in the construction on concretedams 16 th ICOLD. San Francisco. Q 62. GR.SCOLD (1999) Gua tcnica de seguridad de

presas. 3. Estudios geolgico-geotcnicos yprospeccin de materiales. Ed. CNEGP(SCOLD) 287 pp (in spanish).SNELL & KNIGTH (1991) Suceptibility of

dams to filure by sliding on sub-foundation stratathat dip upsteam. 17 th ICOLD Vienna, Q66R88.VAN SCHALKWYK (1982) Geology andselection of the type of dam in South Africa. 14th ICOLD. Ro de Janeiro.Q51. R 44VAN SINT M.L. (1993) Examples of rockengineering in Chile in Comprehensive rockengineering. Ed. J. Hudson. Ed. PERGAMON.Vol. 5, p 812.

ZEBALLOS M. & SORIANO A. (1993).Deformabilidad del cimiento de presas de

fbrica. IV Jornadas Espaolas de Presas.SCOLD (Spanish ICOLD). Murcia. Pp 323-337(in Spanish).

ACRONYMS FOR TYPE OF DAM

CVC Dam Dam built with conventionalvibrated concrete

RCC Dam Dam built with rolled compactedconcrete

CFRD Rockfill dam with concrete faceAFRD Rockfill dam with asphalt face

DEFINITIONS

WR Rating of the fifth parameter (water) inRMR

RMRB Basic RMR, with no adjusting factor forjoints orientation.

RMRBD Dry basic RMR, with no adjusting factorfor joints orientation. WR = 15

RSTA Adjusting factor for joint orientation(dip) related to dam stability (Table 3)

CF Geometric correcting factor for relativeorientation (dip direction) of joints anddam axis.CF=(1-sin(d-j))2 if d>jCF=(1-sin(j-d))

2 if j>dd Direction upstream-downstream of the

dam axisj Dip direction of the significative joint

for dam stability.DMRSTA DMR related to dam stability

DMRSTA= RMRBD+ CF x RSTAEm Deformation modulus of rock mass.

Emax Maximal deformation modulus of rock

mass.Emin Minimal deformation modulus of rockmass.

Ec Deformation modulus of concreteECVC Deformation modulus of conventional

vibrated concreteERCC Deformation modulus of roller

compacted concreteDMRDEF RMR related to relative deformability,

with WR = 5 and no adjusting factorfor joints orientation. (Table 7)


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4thIntSympRollerCompConcr 2003 DMR NovaClassificaçãoRMRparaFundaçõesBarragens Romana