International Journal of Rock Mechanics & M

mf

A

atio

f A

for

4 D

Q,

r r

g r

as F

assigned. The most common systems quantify the rock

systems will include a large scatter above and below ageneral trend. It would therefore be appropriate to

at the Norwegian Geotechnical Institute by Barton, Lien,

thus be dened as a scalar function of the components rockstructure and joint conditions, i.e., F F BS; JC. Equi-potential contours may thus be drawn in the rock

ARTICLE IN PRESSstructurejoint conditions coordinate system, with thecomponent rock structure as the ordinate and thecomponent joint condition as the abscissa.

1365-1609/$ - see front matter r 2006 Elsevier Ltd. All rights reserved.

doi:10.1016/j.ijrmms.2006.08.003

Corresponding author. Tel.: +30210 777 80 86;fax: +30210 770 55 88.

E-mail address: stetzam@igme.gr (S. Tzamos).mass quality as a scalar value that is a function, linear ornon-linear, of the above-mentioned independent para-meters. However, contrary to the term rock mass, theparameters used are not related to the rock mass itself.Stress regime, water pressure, and direction of excavationare examples of parameters employed by various systemsthat do not characterize the rock mass quality but theconstruction of the project as a whole. Further, the aspectsconsidered as important by the systems are not common toall of them. Therefore, any attempt to correlate these

Lunde [3], and evolved to its nal state by Grimstad andBarton [4] with minor updates by Barton [5]; the GSIsystem introduced by Hoek [6] and evolved over the yearsinto its contemporary state by Marinos and Hoek [7]; andthe RMi system introduced by Palmstrom [8] and devel-oped over the years by Palmstrom [9,10].Common parameters in these systems are those con-

cerning rock structure and joint surface conditions (JC), inwhich the rock structure may be quantied by the blocksize (BS). A Rock Mass Fabric Index, denoted as F, mayIndex chart. The validity of the chart is tested using data extracted from various projects. The use of the chart simplies input, correlates

rock mass classication systems and improves their utility.

r 2006 Elsevier Ltd. All rights reserved.

Keywords: Rock mass; Classication; Block size; Joint conditions

1. Introduction

Rock mass classication systems try to consider the mostimportant aspects affecting the rock mass, in order to rateits quality. These aspects, assumed to be independent fromeach other, become parameters to which ratings are

correlate the parts of the quality ratings of these systemsthat are common and concern the rock mass only.Four such classication systems are investigated, i.e., the

RMR or CSIR system introduced by Bieniawski [1],modied over the years and arrived in its contemporarystate by Bieniawski [2]; the Q system developed originallystructure and joint conditions i.e., F F BS; JC. All rock mass classication systems ratings are grouped together in a common FabricA correlation of four rockthrough their

S. Tzamosa,,aInstitute of Geology and Mineral Explor

bNational Technical University o

Received 26 April 2006; received in revised

Available online

Abstract

Four classication systems are investigated in this work, RMR,

concern and characterize solely the rock mass, are those used fo

structure is quantied by the block size or the discontinuity spacin

joint conditions ratings (JC). A Rock Mass Fabric Index, denotedining Sciences 44 (2007) 477495

ass classication systemsabric indices

.I. Soanosb

n , Mesoghion 70, 115 27 Athens, Greece

thens, 157 80 Zografou, Greece

m 13 July 2006; accepted 29 August 2006

ecember 2006

GSI and RMi. The common parameters of these systems, which

ating the rock structure and the joint surface conditions. Rock

atings (BS) and the joint surface conditions are quantied by the

, may thus be dened as a scalar function of the components rock

www.elsevier.com/locate/ijrmms

ARTICLE IN PRESSocIn the RMR system, the parameters concerning rockstructure are the drill core quality RQD and the spacing ofdiscontinuities, denoted as parameters R2 and R3. Theirsum, R2+R3, denes the ordinate component, which maybe related to the block size. The abscissa component, whichrepresents condition of discontinuities, is dened by the

Nomenclature

sci uniaxial compressive strength of intact rockmaterial

S spacing of joints within a setJv Volumetric joint count ( the number of joints

per m3)RQD rock quality designationRMR rock mass rating in the Geomechanics classi-

cation system, P6i1Ri, where, R1 is therating for intact rock strength, R2 is the ratingfor RQD, R3 is the rating for discontinuityspacing, R4 is the rating for discontinuityconditions, R5 is the rating for ground water,and R6 is the rating for discontinuity orienta-tion

Q rock mass quality value in the Q classicationsystem, given by Q RQD=JnJr=JaJw=SRF or Q BSQ JCQ ST , and Q0 RQD=JnJr=Ja or Q0 BSQ JCQ, where,Jn is the factor for joint set number, Jr is the

S. Tzamos, A.I. Sofianos / International Journal of R478parameter denoted as R4. The sum

FRMR R2 R3 R4 (1)denes the rock mass fabric index of the system. Its rangeextends from 8 to 76.In the Q system, parameters concerning rock structure

are the RQD and the joint set number Jn. Their ratio is theordinate component and represents block size. Jointcondition parameters are accounted by the parametersjoint roughness number Jr and joint alteration number Ja.Their ratio is the abscissa component that represents jointcondition and may be related to inter block shear strength.The product of the abscissa and the ordinate componentsdenes the rock mass fabric index of the system, i.e.,

FQ RQD

Jn

Jr

Ja Q0. (2)

The range of the index extends from 0.0208 (forRQD 10, Jn 20, Jr 1, Ja 20) to 1000, as statedin [11].In the GSI system, the rock structure is dened directly

in the ordinate component of the GSI chart, whereas thejoint condition is dened in the abscissa component.However, the denition of each of the components is quitesubjective as it is based on non-scaled sketches andlinguistic non-quantied terms. The work by Sonmez andUlusay [12] and Cai et al. [13] allowed for a quanticationof these rock structure and joint condition components,and for a more objective denition of them. The rock massfabric index FGSI is the geological strength index dened onthe GSI contour lines of the chart, i.e.,

factor for joint roughness, Ja is the factor forjoint alteration and lling, Jw is the factor forjoint water pressure or inow, SRF is the stressreduction factor, and BSQ RQD=Jn blocksize, JCQ Jr=Ja joint conditions, ST Jw=SRF active stress coefcient

RMi Rock Mass Index, given by RMi sci JP,where JP is the jointing parameter 0:2 jCp VDb ;D 0:37 jC0:2, jC is the jointconditions rating, Vb the block volume (m

3), Lthe mean block diameter [10] ( mean jointspacing) Vb3

p SjK joint waviness factor (large scale planarity of

joint wall)FGSI Rock Mass Fabric Index for the GSI system-

GSI

FQ Rock Mass Fabric Index for the Q system Q0FRMR Rock Mass Fabric Index for the RMR

system R2+R3+R4FRMI Rock Mass Fabric Index for the RMi sys-

tem JP

k Mechanics & Mining Sciences 44 (2007) 477495FGSI GSI . (3)In the RMi system, the rock structure ordinate

component is represented by the block volume Vb, whereasthe abscissa component, i.e., the joint condition, isrepresented by the joint condition factor jC. The rockmass fabric index FRMi of the system is equal to the jointingparameter JP, which is given by

FRMi JP 0:2jC

pVDb ;D 0:37 jC0:2. (4)

The range of the index extends from 0.00001 to 1.Correlation between the four classication systems is

attempted in terms of their Rock Mass Fabric Indices. Thefour indices depend on the same two components;however, these components are not scaled to a commonbase. Correlation therefore necessitates the scaling of thetwo components of each Rock Mass Fabric Index in acommon base.

2. Rock mass fabric indices components

2.1. Rock structure component

Block size may be chosen as the common entityquantifying the rock structure in the various systems.It is related to the discontinuity spacing and the drillcore quality. Discontinuities delineate the independent

ARTICLE IN PRESS

ad

crac

roc

ed,

separated

not have planes of weakness

is quite common

d joints. Huge blocks intimately interlocked

y or may not be cemented

not require lateral support. Spalling may occur

s spaced. Block size is about 1m in size, intimate interlocking

r may not be healed

ocTable 1

Terzaghis [14] rock mass classication, with adjustments by Sinha [15], as

Rock class Rock type Description

I Hard and intact BS: No joints or

JC: Unweathered

Failure: If fractur

scm4150MPa

II Hard stratied and

schistose

BS: Layers widely

JC: May or may

Failure: Spalling

III Massive and

moderately jointed

BS: Widely space

JC: The joints ma

Failure: Walls do

IV Moderately blocky and

seamy

BS: Joints are les

JC: Joints may o

S. Tzamos, A.I. Sofianos / International Journal of Rblocks found in the rock mass. The block size isdescribed qualitatively and quantitatively by manyauthors.Terzaghi [14] was the rst to classify rock mass into

categories dened by the block size. His descriptions aredened linguistically and many authors have extended thisclassication to accommodate numerical values of theblock size. Table 1 displays Terzaghis rock mass classes asadjusted by Sinha [15].Discontinuity spacing is standardized by ISRM [17]

relating qualitative descriptions with numerical measure-ments, shown in Table 2. This standardization is alsofollowed by the RMR system. According to the RMRsystem, the sum R2+R3 ranges from 8 to 40 and can betaken as a measure of the block size. Fig. 1 plots thecombined RQD (R2) and spacing ratings (R3), as shown byBieniawski [2].In the Q system, block size is dened by the ratio RQD/

Jn [3], which may be expressed [18] in cm units, as it takesvalues from 0.5 to 200.

Failure: The rock ma

V Very blocky and seamy BS: Closely spaced jo

fragments which are

Failure: Some side pr

Vertical walls may re

VI Completely crushed but

chemically intact

BS: Comprises chemi

interlocking. Block si

VII Squeezing rock

moderate depth

Failure: Squeezing is

without perceptible in

1501000m

VIII Squeezing rockgreat

depth

Failure: The depth m

1000m (2000m in ve

IX Swelling rock Failure: Rocks contai

can swell. Some shale

volume change and is

water. Heavy pressurapted from Palmstrom [16]

ks

k

it breaks across intact rock. At high stresses rock burst may occur.

k Mechanics & Mining Sciences 44 (2007) 477495 479Palmstrom [9] standardized qualitative rock massstructure descriptions with their numerical equivalents, asshown in Table 3. Block size and discontinuity spacing canbe measured by means of the Volumetric Joint Count Jv, orthe mean block volume, Vb. The values of the table arevalid for blocks that are equidimensional, but include someerror if they are moderately long or at. If thesemeasurements are not easily obtained in the eld the mean

y or may not be hard. No side pressure is exerted or expected

ints. Block size is less than 1m. It consists of almost chemically intact rock

entirely separated from each other and imperfectly interlocked

essure of low magnitude is expected

quire support

cally intact rock having the character of a crusher run aggregate. No

ze could be few cm to 30 cm

a mechanical process in which the rock advances into the tunnel opening

crease in volume. Moderate depth is a relative term and could be up to

ay be more than 150m. The maximum recommended tunnel depth is

ry good rocks)

ning swelling minerals such as montmorillonite, illite, kaolinite, and others

s absorb moisture from the air and swell. Swelling is associated with

due to the chemical change of the rock usually in presence of moisture or

e is exerted on rock supports

Table 2

Discontinuity spacing descriptions according to ISRM [17]

Discontinuity spacing Description

o20mm Extremely close2060mm Very close

60200mm Close

2060 cm Moderate

60 cm2m Wide

2m6m Very wide

46m Extremely wide

ARTICLE IN PRESS

nd

ocFig. 1. Relation between RQD a

S. Tzamos, A.I. Sofianos / International Journal of R480discontinuity spacing can be used. Moreover he states thatthe use of the Jv coefcient or the mean block volume Vbcharacterize rock structure better than the use of RQD.According to Sonmez and Ulusay [12] block size in the

GSI chart is quantied by the Structure Rating coefcient(SR) that is related to the Jv coefcient with the followingformula:

SR 17:5 logJv 79:8. (5)The structure rating may take values from 0 to 100. Such

a quantied GSI chart is shown in Fig. 2.Cai et al. [13] suggest that the block size in the GSI chart

is quantied by the mean discontinuity spacing S or by themean block volume Vb. For cases where more than threeregular joint sets occur, block volume Vb can be foundfrom the joint spacings as

Vb S1S2S3

sin g1 sin g2 sin g3, (6)

where S1, S2, S3 are the spacings between the individualjoints in each set, and g1, g2, g3 are the angles between thejoint sets. For a rhombohedral block, the block volume isusually larger than that of cubic blocks with the same joint

Table 3

Classication of block volume according to Palmstrom [9]

Degree of jointing or (density of joints) Joint spacing S (Block diameter) S

Massive/no joints 410mMassive/very weakly jointed 310m

Weakly jointed 13m

Moderately jointed 30 cm1m

Strongly jointed 1030 cm

Very strongly jointed 310 cm

Crushed o3 cmmean discontinuity spacing [2].

k Mechanics & Mining Sciences 44 (2007) 477495spacings. However, Cai et al. [13] state that compared tothe variation in joint spacing, the effect of the intersectionangle between joint sets is relatively small, and the blockvolume Vb can be approximated for practical purpose as

Vb S1S2S3. (7)If in doubt, they suggest the measurement of some

representative blocks in the eld or the use of RQD or Jv.The quantied GSI chart according to Cai et al. [13] ispresented in Fig. 3.Barton et al. [20] classify the rock mass into categories I,

IIa, IIb, IIIa, IIIb (Table 4). For every rock mass categorythere are: brief descriptions of rock mass properties, thenumber of the joint sets encountered, the discontinuityspacing, the rock mass quality Q, the rock mass failuremode and the suggested numerical tools/methods fordesign.

2.2. Discontinuity conditions component

Discontinuity conditions are rated in the RMR systemby means of the R4 rating (ranging from 0 to 30) takinginto account the persistence, roughness, weathering, inll

Vb3p

Volumetric joint count Jv Block volume Vb

Extremely low o0.3 Extremely large size 41000m3Very low 0.31 Very large size 301000m3

Low 13 Large size 130m3

Moderately high 310 Moderate size 0.031m3

High 1030 Small size 130 dm3

Very high 30100 Very small size 0,031 dm3

Extremely high 4100 Extremely small size o30 cm3

ARTICLE IN PRESSock MS. Tzamos, A.I. Sofianos / International Journal of Rmaterial and joint aperture. Total rating R4 is calculated bythe average of individual ratings for every discontinuity set.The Q system rating for joint conditions is expressed by

the ratio Jr/Ja. Only the most unfavorable joint set for theproject construction is rated.The RMi system according to Palmstrom [8] takes

into account, in addition to jR and jA, the large-scalejoint waviness jK factor described in Table 5 and the jointsize and continuity factor jL. The joint condition coef-cient of the RMi is expressed as jC jL jKjR=jA.Coefcients jR and jA are similar to Jr and Ja of the Qsystem.According to Sonmez and Ulusay [12], discontinuity

conditions in the GSI chart are numerically expressed bythe surface rating coefcient, SRC. This coefcient usesthree individual subratings of the R4 ratings of the RMRsystem, i.e., ratings for roughness, weathering degree andinlling material, as shown in Table 6.According to Cai et al. [13] discontinuity conditions

described in the GSI chart can be quantied with the use ofthe Jc coefcient that is similar to the one described in the

Fig. 2. QuanticationRM

wh10co

3.

3.1

(BrelmeSh

ofechanics & Mining Sciences 44 (2007) 477495 481i system, dened as Jc jKjR=jA. Thus, jC jLJc,ere jL 1 or 0.75 for joint persistence 110m and30m, respectively. The Jc coefcient is used fornsistency with the quantication of Cai et al. [13].

Common base for the Rock Mass Fabric Indices

. Block size component

Discontinuity spacing (S) and block sizeSQ RQD=Jn) as dened by the Q system are closelyated. Fig. 4 plots the relation of block size BSQ to thean discontinuity spacing S and to the block volume Vb.own in the chart are:

Scatter data points extracted from Palmstrom [10]. Theywere generated by a computer program that simulateslines penetrating blocks in different angles. Lowhighbars extracted from a database of constructed tunnels.They dene the average value of BSQ together with theminimum and maximum of the standard deviation of

the GSI [12].

ton

ARTICLE IN PRESSocS. Tzamos, A.I. Sofianos / International Journal of R482every joint spacing class. The average and standarddeviation ranges used in this chart illustrate better therelation between BSQ and S as standard deviationcovers the 66% of the variability in the data.An area enclosed by dashed lines, of possible BSQ valuesfor pertinent joint spacings. The area limits were evolvedusing the chart of Fig. 1 [2].

It is observed that the logarithm of BSQ is a mono-ically increasing function of the logarithm of disconti-

Fig. 3. Quanticationk Mechanics & Mining Sciences 44 (2007) 477495nuity spacing or of the block volume. There is a highscatter in data records where joint spacing is less than10 cm, as in this case the rock mass is heavily jointed andmore than four joint sets are present; the Jn coefcientvaries accordingly in this category introducing variability.The chart of Fig. 4 is useful as a reference for the scaling ofblock size BSQ values with the joint spacing or the blockvolume.In Table 7, the rock structure descriptions by four

authors are grouped together. Most of their linguistic

of the GSI [13].

ARTICLE IN PRESS

De

Fin

me

or

ele

(BE

ocTable 4

Rock mass behaviour, adapted from Barton, Bandis, Shinas [20]

Rock mass description Failure

Intactmassive

Extremely massive

rock mass, high

strength, rough

joints, strong

dilution

Continuum Intact rock

failure,

sliding of

individual

joints

Intactjointed

S. Tzamos, A.I. Sofianos / International Journal of Rdescriptions are similar. In order to have a common base,the linguistic description of rock mass structure providedby the GSI system in the 4th column of the table isadopted. In Table 8, the adopted rock structure descrip-tions are related to the joint spacing categories provided byvarious authors and systems. Thus, in columns 2 through 6,the joint spacing ranges as given by ISRM [17], Bartonet al. [20], Cai et al. [13], Bieniawski [2] and Palmstrom [9]are related to the selected GSI descriptions, given incolumn 1. Palmstroms joint spacing categories havealready been found by various authors to be suitable forthe quantication of the GSI rock structure categories.In Fig. 5, the chart displays all rock mass structure

parameters that are used for the denition of the block sizeby the four classication systems and allows easy selection

Massive, low

jointed, unaltered,

rough joints,

medium dilution

Sliding of

some joints

3

Mediumhigh

jointed,

weathered,

smooth

undulating joins,

medium dilution

Discontinuous Sliding of

many joints

Di

ele

(D

UD

or

Moderately disturbedheavily jointed

Heavily jointed,

weathered weak

rock mass, light

dilution

Rotated shear 3

Very disturbed (tectonically)

Very weak,

altered, squeezing

rock mass, if clay

is present; no

dilution (Fault

zone)

Continuum Weakness

and Shear

zones. Clay

presence

Fin

me

or

dif

me

eg.sign Joint sets Q Joint spacing

S

Span/S

ite element

thod (FEM)

boundary

ment method

M)

1001000 42m 55

k Mechanics & Mining Sciences 44 (2007) 477495 483and transition between them. The scaling of everyparameter is performed using the descriptions of theauthors dened earlier in Section 2.1 and this section. Inthe rst column the rock mass description, as in the GSIchart, is displayed; there exists a picture of a typical rockmass structure together with the possible joint sets.Category Low Jointed is added, as Q, RMR and RMisystems may be applicable in this category. In the 2ndcolumn, the average joint spacing is shown, as given byPalmstrom in Table 8. In column 3, the sum of R2 (RQDrating) and R3 (discontinuity spacing rating) of the RMRsystem is displayed. The sum R2+R3 is calculated using thediscontinuity spacing of column 2 and the combinedratings of Fig. 1. The R3 values of the low jointed andmassive categories are raised by 30%, according to

13 10100 0.52m 520

screte

ment method

EM) eg.

EC/3DEC

DDA

24 110 1050 cm 20100

44 0.11 510 cm 100500

ite element

thod (FEM)

nite

ference

thod (FDM)

FLAC

o0.1 o5 cm b500

Bieniawskis [2] suggestions. Q systems block size BSQ RQD=Jn is presented in column 4. The BSQ value rangesare dened in the domains 1 though 6 of Fig. 4 forpertinent S values of column 2. The mean block volume Vb(in cm3), the volumetric joint count, Jv and the SRcoefcient are shown in columns 5, 6 and 7, respectively.They are used by the RMi system and also for thequantication of the GSI chart. Values are plotted asdescribed in Fig. 2 [12] and Fig. 3 [13] for all rock masscategories except the low jointed one. As stated before theVb values should be applicable for blocks dened ascommon, or nearly equidimensional, or moderately long orat.Overall, Fig. 5 provides rock structure numerical

parameters as required by the four classication systemsscaled to t the rock mass categories of the GSI chart. Thegure will be used below as the rock structure componentin the rock mass fabric (BS, JC) coordinate system.

ARTICLE IN PRESS

Table 5

Joint condition factor after Cai et al. [13]

Waviness terms Undulation a/D jK rating

Interlocking (large-scale) 3

Stepped 2.5

Large undulation 43% 2Small to moderate undulation 0.33% 1.5

Planar o0.3% 1

a maximum asperity amplitude, D length between maximum ampli-tudes.

Jc jK jR

jA

jK waviness coefcient, jR and jA similar to Q systems Jr and Ja

coefcients.

Table 6

Surface conditions rating after Sonmez and Ulusay [12]

Variable Rating

Roughness Very rough Rough Slightly rough Smooth Slickensided

Rr 6 5 3 1 0

Weathering Unweathered Slightly weathered Moderately weathered Highly weathered Decomposed

Rw 6 5 3 1 0

Inlling material None Hard lling o5mm Hard lling 45mm Soft lling o5mm Soft lling 45mmRf 6 4 2 2 0

SCR Rr+Rw+Rf

Fig. 4. Relation between block size (BSQ RQD=Jn) and discontinuity spasimulation of lines penetrating blocks in different angles, from Palmstrom [10].

of all data points) of data collected from constructed underground openings. D

of Fig. 1. Numbered rectangular areas show the ranges of the rock mass c

5 Blocky/Disturbed, 6 Disintegrated.

S. Tzamos, A.I. Sofianos / International Journal of Rock Mechanics & Mining Sciences 44 (2007) 477495484cing S or block volume Vb. Dots are data generated from a computer

Highlow bars indicate average and standard deviation distribution (66%

ashed lined area denes possible BSQ ranges according to RQDS relationsategories. 1 Massive, 2 Low Jointed, 3 Blocky, 4 Very Blocky,

ARTICLE IN PRESSocTable 7

Qualitative denition of rock mass structure

Terzaghi [14] Palmstrom [9] Barton et al. [20]

I. Hard and intact Massive/no joints I. Intactmassive

Massive/very weakly

jointed

Extremely massive

rock mass, high

S. Tzamos, A.I. Sofianos / International Journal of R3.2. Joint conditions component

Descriptions of discontinuity conditions according tovarious authors and systems are grouped in Table 9. In therst column of this table the linguistic descriptions of the GSIsystem are presented. The 2nd column shows the SCRcoefcient given by Sonmez and Ulusay [12]. The SCR iscalculated from the RMR R4 rating without ratings for

strength

III. Massive and

moderately jointed

Weakly jointed IIa. Intactjointed

Massive, low jointed

IV. Moderately

blocky and seamy

Moderately jointed IIb. Intactjointed

Mediumhigh jointed

V. Very blocky and

seamy

Strongly jointed IIIa. Moderately

disturbedheavily

jointed

Heavily jointed rock

mass

Very strongly jointed IIIb. Very disturbed

tectonically

VI. Completely

crushed but

chemically intact

Crushed Very weak, altered,

squeezing rock mass,

in presence of clay.

(Fault zone)Hoek [6] GSI

Intact or massive

k Mechanics & Mining Sciences 44 (2007) 477495 485persistence and aperture as shown in Table 6. Column 3holds Jc ratings as stated by Cai et al. [13]. The Jc ratings arealso used for the calculation of FRMi as jC jL Jc andjL 1 or 0.75 for joint persistences 110m and 1030m,respectively. In the 4th column, the RMR R4 rating ispresented. Ratings are calculated as of SCR, assuming smallpersistence and aperture in very good joint conditions; indegrading surface qualities persistence and aperture are

Low jointed (not

applicable in the GSI

system)

Blocky

Very blocky

Blocky-disturbed

Disintegrated

disincvapr

Q

ARTICLE IN PRESS

n et al.

ble 4

cm

0 cm

cm

m

ock Massumed to increase accordingly. Column 5 holds the Jr/Jacoefcients of the Q system. Q ratings are applied for everydiscontinuity category according to the linguistic descriptionsof discontinuity conditions found in the GSI chart. Theratings are linearly distributed in the logarithmic space fromthe very poor to the very good categories.Fig. 6 displays the discontinuity condition ratings given

in Table 9, which can be used for the calculation of theabscissa component in the rock mass fabric (BS, JC)coordinate system. In this way, equivalent ratings areavailable for the denition of discontinuity conditions bythe four classication systems.

Table 8

Joint spacing denitions

1 2 3

GSI Hoek [6] Rock mass

structure description, Joint sets

ISRM [17] cf.

Table 2

Barto

cf. Ta

1 Intact or massive 4200 cm 4200None or random joints

2 Low jointed 60200 cm 5020

1 or 2 Joint sets

3 Blocky 2060 cm 1050

3 Joint sets

4 Very blocky 620 cm 510 c

43 Joint sets

5 Blockydisturbed 26 cm 15 cm

44 Joint sets

6 Disintegrated o2 cm o1 cmMany joint sets

S. Tzamos, A.I. Sofianos / International Journal of R4863.3. Common base for all Rock Mass Fabric Indices

The block size and discontinuity conditions selectioncharts given in Figs. 5 and 6, are used to form the rock massfabric chart of Fig. 7. This chart offers easy estimation of therock mass fabric indices of the four selected classicationsystems, i.e., RMR, Q, GSI and RMi. The chart follows theGSI concept of a rock structure ordinate and a discontinuitycondition abscissa. Moving from left to right in the chart,discontinuity surface quality is decreasing. Moving from upto down, interlocking of rock pieces is also decreased.Overall rock mass fabric quality is decreasing from verygood quality in the upper left of the chart to very poorquality in the bottom right. Some equipotential contours ofthe four Rock Mass Fabric Indices are also drawn to helpthe reader visualize better the relations among them.Nevertheless, in all circumstances the user must initiallycalculate the ordinate and abscissa components to arrive atan estimate of the Rock Mass Fabric Index.As the rock mass structure ordinate incorporates a visual

appearance of the rock mass together with the expectednumber of joint sets and various system ratings, the usercan choose from the most handy ones, in order to nallythe appropriate BSQ and JCQ values, either by directmeasurements or by estimating other system para-meters. Their product is the FQ index. Traced contoursof FQ in the chart are straight lines as the (BSQ, JCQ)ratings are linearly distributed in the log space.

For the estimation of the FRMR index, the user must nd

quire the appropriate rating. The same is followed for thecontinuity conditions abscissa of the chart, whichorporates both linguistic descriptions and numericallues in order to interpolate the required rating. Theocedure is easily summarized as follows:

For the estimation of the F index, the user must ndac310 cm o6 cm 310 cm

o3 cm o3 cm[20] Cai et al. [13] cf.

Fig. 3

RMR Bieniawski

[2]

Palmstrom [9] cf.

Table 3

4100 cm 4200 cm 4300 cm

60200 cm 100300 cm

30100 cm 2060 cm 30100 cm

1030 cm 620 cm 1030 cm4 5 6

echanics & Mining Sciences 44 (2007) 477495the appropriate R2+R3 and R4 values. Their sum is theFRMR index. Traced contours of FRMR in the chart arenot straight lines. This is due to the fact that the R2+R3ratings as given by Bieniawski [1,2] are not linearlydistributed in this rock structure space.For the estimation of the FGSI index the user maydirectly evaluate the index from the GSI chart (asFGSI GSI). The index may also be evaluated moreobjectively by establishing the appropriate rating pairs.The pairs may be either SR (or Jv) as ordinate and SCRas abscissa, or Vb as ordinate and Jc as abscissa. Somecontours of FGSI are drawn in the chart. The followingformula is found to give a good t for the index:

FGSI GSI 2:25 SR=120SCR 0:33SR 5. (8)The formula has a very high correlation of 99% withlower accuracy near the borders.The FRMi index is calculated from the appropriate pairof (Vb,Jc) with the use of formula (4); Jc is dened inSection 3.2. The traced contours of FRMi are exponentialcurves as the relation between rock structure anddiscontinuity conditions components in Eq. (4) is non-linear.

ARTICLE IN PRESSocS. Tzamos, A.I. Sofianos / International Journal of RAn example, a blocky rock mass with good to fair jointconditions is rated as below:Rock mass structure: SR 65, RQD=Jn 8,

Vb 105 cm3 0:1m3, R2 R3 31.

Fig. 5. Block size sk Mechanics & Mining Sciences 44 (2007) 477495 487Joint conditions: SCR 12, Jr=Ja 1, Jc 1:7,R4 19.By visually examining Fig. 7, the Fabric Indices

take approximate values: FGSI 60, FRMR 50, FQ 8

election chart.

ARTICLE IN PRESS

[12

ock MTable 9

Description of discontinuity conditions

1 2

Hoek [6] GSI Sonmez and Ulusay

Very good 1814

Very rough, fresh, unweathered surfaces

Good 1114

Rough, slightly weathered, iron stained surfaces

Fair 711

Smooth, moderately weathered or altered surfaces

Poor 3.57

Slickenslided, highly weathered surfaces with

compact coatings or llings of angular fragments

Very poor 03.5

Slickenslided, highly weathered surfaces with soft

clay coatings or llings488(logFRMlineB

Eq.+5FRM0:37R

roczoooffebloT

rocraticom

4. A

Fchadiscfoll

(1)

FS. Tzamos, A.I. Sofianos / International Journal of Rarithmic distance, closer to the FQ 10 line) andi 0:12 (logarithmic distance between the 0.5 and 0.1s).y calculating the rock mass components: FGSI (using(8)) (2.25+65/120) 12+0.33 65+5 33.5+21.45 59.95, FRMR 31 19 50, FQ 8 1 8 andi (using Eq. (4)) 0:2

1:7

p 0:1D, where D

1:70:2; thus, FRMi 0:1212.ock structure ratings are more consistent in the jointedk mass categories numbered 36. For this reason, am of the chart of Fig. 7 is shown in Fig. 8. The gurers better resolution for the selection of parameters incky to disintegrated rock masses.he charts of Figs. 7 and 8 offer determination of thek mass fabric indices by employing the most handyngs or descriptions to the user. The latter should bepatible to the classication system restrictions.

pplications

or the validation of the proposed rock mass fabricrts various projects were examined. Rock structureontinuity conditions ratings were extracted from theowing projects:

Shallow diversion tunnel at Guledar dam site, Turkey

[21]. The main purpose of the construction of the

(2)

(3)

(4)

(5)

ig. 6. Chart for the selection of discontinuity surface conditions. (above foundation) has been successfully completed atTenerife Island. The foundation of the tower, a 2-mthick reinforced concrete slab, is supported by jointed,vesicular and weathered basalt, and scoria. Rock typesare: (d1) massive or vesicular basalt with thin scoriac-eous levels, (d2) weathered scoriaceous basalt andpyroclastic breccia, (d3) scoria and fractured pyroclas-tic breccia. RQD for d3 type is reported as 0 and is setplanned tunnel is to regulate, drainage and providewater for irrigation purposes. The diversion tunnel runsmainly through formations of limestone, sandstone anddiabase. Rock masses at the site were characterizedusing RMR, Q, RMi and GSI. Q parameters were notmentioned but were rated according to the descriptionsin the article.Excavation for the foundation of a 40-storey tower in

Tenerife, Spain [22]. A 132.70-m-high apartment tower0.671.7 1017 0.120.5

0.250.67 410 0.070.12

0.10.25 04 0.050.07c 4 r a

4.512 2330 1.75.33

1.74.5 1723 0.51.7] SCR3 4 5

Cai et al. [13] J RMR R Q System J /J

echanics & Mining Sciences 44 (2007) 477495to 10 for FQ estimation according to the Q systemsrecommendations [3].Tunnel behavior in the Istanbul Metro [23]. A tunnel forthe Constantinople Metro was excavated under adensely populated area. Rock masses consist ofalternating sandstones and mudstones, crossed by twodistinct fault systems. There are min/max RMRmeasurements of rock masses and fault zones togetherwith detailed descriptions. From these descriptions Qsystem parameters were generated.The Tuzla Tunnel [24]. This tunnel was excavated mainlyin fault zones, shales and limestones. Classication ofrock masses is performed using the RMR and the GSIsystems. No parameters for the Q system are given.The Beykoz Tunnel [25]. This tunnel was excavatedmainly in weak rocks that were classied as blocky/disturbed, disintegrated and foliated/laminated/shearedrock using the GSI system only, but there is also adetailed list of geotechnical parameters. The rst tworock classes were classied using the mentionedparameters according to the RMR and the Q systems.

ARTICLE IN PRESSock Me(6)

(7)S. Tzamos, A.I. Sofianos / International Journal of RExcavations in chalk rock, Israel [26]. Chalk is widelydistributed and well exposed in Israel. For thousands ofyears tunnels for various purposes have been excavatedin this rock mass. The RMR and Q system ratings wereestimated for many excavations.Design of tunnels in the Sydney region [27]. Details aregiven of the analytical methods used to design rockboltand shotcrete support for tunnels and large span

(8)

Fig. 7. Common chart for all rockchanics & Mining Sciences 44 (2007) 477495 489caverns under relatively low cover in the nearhorizontally bedded Triassic sandstones of the Sydneyregion. Parameters used for the RMR and Q systemsare listed.Half tunnels in Himalaya [28]. Half tunnels along hillroads are excavated as overhangs within steep slopes ofhard rocks. Rock mass properties pertaining to Q andRMR for the rocks exposed around the half tunnels

mass fabric indices.

TholColtosomsug

ARTICLE IN PRESSocS. Tzamos, A.I. Sofianos / International Journal of R490have been evaluated. The R3 ratings mentioned wereraised by 30% for cases were 2 or less joint sets werepresent, according to Bieniawskis [2] suggestions.

he gathered data is given in Table 10. Columns 1 and 2d the site name and section described previously.umns 3, 4, 6 and 7 hold the measured ratings accordingthe RMR and Q systems. Columns 9 and 10 displaye SR and SCR ratings, measured according to thegestions made [12]. Column 11 displays FGSI ( GSI)

Fig. 8. Zoom in the common chartk Mechanics & Mining Sciences 44 (2007) 477495as measured. The rock mass fabric indices FRMR and FQ incolumns 5 and 8 were calculated from the relevant ratingsgiven in the pertinent columns.Table 11 shows the estimation of the rock mass fabric

indices from ratings of other systems shown in Table 10.In columns 3 and 4 (Table 11) the FRMR componentsare evaluated from the pertinent values of the Qsystem given in columns 6 and 7 of Table 10 using theselection chart of Fig. 7. The FRMR index shown in column5 (Table 11) is estimated from columns 3 and 4 (Table 11).

for all rock mass fabric indices.

In columns 6 and 7 (Table 11) the FQ components areevaluated from the pertinent values of the RMR systemgiven in columns 3 and 4 of Table 10. The FQ index shownin column 8 (Table 11) is estimated from columns 6 and 7(Table 11). In columns 9 and 10 (Table 11) the FGSIcomponents are evaluated from the pertinent values of theQ system given in columns 6 and 7 of Table 10. The FGSI

index shown in column 11 (Table 11) is estimated fromcolumns 9 and 10 (Table 11).From the data collected a comparison is made, shown in

Fig. 9, between measured and predicted values of the rockmass fabric indices. It is shown that there is an agreementbetween measured and predicted data with limited scatterand high correlation coefcients. In Fig. 9a, the predicted

ARTICLE IN PRESS

Table 10

Measured data, from published papers

1 2 3 4 5 6 7 8 9 10 11

Site Section RMR system Q system GSI system

R2+R3 R4 FRMR BSQ JCQ FQ SR SCR FGSI

1. Guledar Dam Turkey [21] Limestone 23 11 34 7.67 0.32 1.88 43

Sandstone 16 8 24 5.67 0.2 0.45 33

Diabase 13 3 16 1.87 0.08 0.12 19

2. Tenerife Spain [22] d1 27 25 52 5.5 1.5 8.25 62 12 52

d2 16 20 36 2.83 1.5 4.25 25 11 39

d3 8 15 23 0.56 0.75 0.42 5 8 28

3. Constantinople metro [23] Sandstone 28 20 48 8.33 1.5 12.5 62

Sandstone 16 20 36 5.56 0.333 1.85 43

Mudstone 23 20 43 4.17 0.667 2.78 52

Mudstone 16 10 26 2.08 0.25 0.52 30

Fault zone 18 10 28 1.25 0.125 0.16 19

Fault zone 8 0 8 0.75 0.05 0.04 18

4. Tuzla tunnel [24] Blocky 23 14 37 35

Breciated 11 6 17 25

Clayey 8 0 8 15

5. Beykoz tunnel [25] Blocky 16 20 36 2 0.5 1

Disintegrated 8 8 16 1 0.1 0.1

6. Excavations in chalk rock, Israel [26] Rosh-Haniqra 21 25 46 8.33 1.0 8.33

Beit-shearim 16 25 41 6.67 1.0 6.67

Mesilat-Zion 16 25 41 2.4 1.5 3.6

Maresha 23 25 48 5 3.0 15

Avedat 23 25 48 5.83 0.67 3.89

Ramat-Hovav 18 25 43 7.5 0.75 5.63

Ein-Ziq 16 25 41 3.58 0.67 2.39

7. Sydney tunnels [27] I 32 25 57 45 3 135

II 31 22 53 20 3 60

III 25 20 45 16.3 0.75 12.2

IV 15 10 25 4.17 0.666 2.78

V 11 10 21 0.83 0.333 0.28

8. Himalaya half tunnels [28] K1 30 25 55 15.3 3 46

K2 30 25 55 15.9 3 48

K3 30 25 55 15.9 3 48

M1 30 30 60 29.5 3 89

3

3

2

2

2

3

2

2

3

S. Tzamos, A.I. Sofianos / International Journal of Rock Mechanics & Mining Sciences 44 (2007) 477495 491M2 33

M3 33

P1 30

P2 30

T1 30

T2 30

T3 30

T4 30

T5 30T6 30 2

T7 30 20 63 31.7 3 95

0 63 30.6 3 92

5 55 21.3 3 64

5 55 20.5 3 62

5 55 15.9 3 48

0 60 15.9 3 48

5 55 16.4 3 49

5 55 16.4 3 49

0 60 16.4 3 495 55 16.4 3 49

5 55 15.9 3 48

from the Q system FRMR index of Table 11, column 5, isplotted against the measured FRMR index of Table 10,column 5; the correlation coefcient is 95%. In Fig. 9b thepredicted, from Q, FGSI index of Table 11, column 11 isplotted against the measured FGSI index of Table 10,column 11; the correlation coefcient is 95%. In Fig. 9c thepredicted, from RMR, FQ index of Table 11, column 8 isplotted against the measured FQ index of Table 10, column

8; the correlation coefcient is 93%. It can be seen in Fig.9a that in good quality rock masses the FRMR predictedfrom FQ is, in general, 37 units more than measured. Asthe scaling of the rock mass components was performedsolely according to the original authors suggestions, arenement of the scaling in good quality rock mass may bepossible in the future, taking into account feedback fromthe users of the charts.

ARTICLE IN PRESS

Table 11

Estimated data, predicted from the charts

1 2 3 4 5 6 7 8 9 10 11

Site Section R2+R3 R4 FRMR BSQ JCQ FQ SR SCR FGSI

From Q ratings From RMR ratings From Q ratings

1. Guledar Dam Turkey Limestone 32 11 43 3.63 0.33 1.2 45 7 38

Sandstone 29 7 36 1.86 0.2 0.37 33 5 27

Diabase 16 2 18 1,41 0.1 0.14 20 2 16

2. Tenerive Spain d1 29 22 51 5.0 2 10.0 57 12 58

d2 21 22 43 2 1.1 2.2 40 12 48

d3 8 18 26 0.5 0.45 0.22 5 10 31

3. Constantinople metro Sandstone 33 22 55 6.03 1 6.0 66 13 65

Sandstone 29 12 41 3.72 1 3.7 57 7 43

Mudstone 25 17 42 3.55 1 3.5 51 10 49

Mudstone 18 10 28 3.72 0.25 0.93 36 6 32

Fault zone 12 5 17 2.24 0.25 0.56 24 4 22

Fault zone 9 0 9 0.5 0.05 0.025 14 0 9

4. Tuzla tunnel Blocky 45 9 43

Breciated 22 4 22

Clayey 0 0 8

5.Beykoz tunnel Blocky 17.5 16 33.5 3.72 1 3.7

Disintegrated 10 3 13 0.5 0.16 0.1

6. Excavations in chalk rock, Israel Rosh-Haniqra 32 20 52 3.16 2.0 6.3

Beit-shearim 31 20 51 1.78 2.0 3.5

Mesilat-Zion 20 22 42 1.78 2.0 3.5

Maresha 28 27 55 3.59 2.0 7.1

Avedat 28 17 45 3.55 2.0 7.1

Ramat-Hovav 31 19 50 2.24 2.0 4.5

Ein-Ziq 23 17 40 1.78 2.0 3.5

7. Sydney tunnels I 40 27 67 7.94 2.0 15.8

II 36 27 63 7.08 1.5 10.6

III 35 19 54 3.98 1.0 4.0

IV 26 17 43 1.59 0.25 0.4

V 9.5 13 22.5 1.15 0.25 0.3

8. Himalaya half tunnels K1 35 27 62 6.31 2.0 12.6

K2 35 27 62 6.31 2.0 12.6

K3 35 27 62 6.31 2.0 12.6

6

6

6

6

6

6

6

6

6

6

S. Tzamos, A.I. Sofianos / International Journal of Rock Mechanics & Mining Sciences 44 (2007) 477495492M1 38 27

M2 38 27

M3 38 27

P1 36 27

P2 36 27

T1 35 27

T2 35 27

T3 35 27

T4 35 27

T5 35 27T6 35 27 6

T7 35 27 65 4.68 5.0 23.4

5 6.31 5.0 31.5

5 6.31 5.0 31.5

3 4.68 2.0 9.3

3 4.68 2.0 9.3

2 6.31 2.0 12.6

2 6.31 5.0 31.5

2 6.31 2.0 12.6

2 6.31 2.0 12.6

2 6.31 5.0 31.52 6.31 2.0 12.6

2 6.31 2.0 12.6

The data collected allowed for a correlation between themeasured FRMR and FQ indices, which is as follows:

FRMR 15 log FQ 32 r 0:96. (9)Further, according to Goel et al. [29], RCR is dened as

RMR without ratings for intact rock strength R1 andorientations of discontinuities R6, while N is Q without theSRF factor. They have proposed the following equationthat relates RCR with N:

RCR 8 ln N 30 r 0:92. (10)In dry conditions RCR FRMR 15, N FQ (assum-

ing Jw 1) and in owing conditions RCR FRMR and

N 0:5FQ (assuming Jw 0:5). Thus, Eq. (10) becomes:FRMR 18:4 log FQ 15 for dry conditions; (11)

FRMR 18:4 log FQ 24:5 for flowing conditions: (12)Eqs. (9), (11) and (12) are plotted in Fig. 10 against

measured data, i.e., FRMR from Table 10, column 5, and FQfrom Table 10, column 8. The proposed correlation Eq. (9)has a high correlation coefcient of 96% for the parti-cular selected data records. The discrepancy betweenEqs. (10)(12) is relatively small and can be attributed tothe fact that the RCRN relation is derived by regressionfrom a different data set where three components were

ARTICLE IN PRESS

0

10

20

30

40

50

60

70

80

0 20 40 60 80

FRMR Measured0 20 40 60 80

FGSI Measured

F RM

R Pr

edic

ted

from

Q .

0

10

20

30

40

50

60

70

80

F GSI

Pr

edic

ted

from

Q .

r = 95.3% r = 95.5%

100

1000

1

Q M

.

a b

c

S. Tzamos, A.I. Sofianos / International Journal of Rock Mechanics & Mining Sciences 44 (2007) 477495 4930.01

0.1

1

10

0.01 0.1

F

F Q Pr

edic

ted

from

RM

R

r = 93.4%Fig. 9. Comparison between predicted from10 100 1000

easuredother systems and measured ratings.

standing and a better overview of the rock mass

ARTICLE IN PRESSoctaken into account, rock structure, joint conditions andground water. The proposed Eq. (9) avoids also thenegative values of FRMR when FQ is low.

5. Conclusions

A correlation of four rock mass classication systems,i.e., RMR, Q, GSI and RMi, is attempted in their commonparts which concern the rock mass. Common parameters inthese systems are those concerning rock structure and jointsurface conditions. Rock structure descriptions were puttogether to form a uniform quick selection chart incorpor-ating linguistic descriptions and numerical values of blocksize. The same procedure was followed for the parametersneeded for the discontinuity conditions rating and a chartwas created incorporating equivalent ratings. The rockstructure chart was used as the ordinate together with thejoint conditions one as the abscissa of a coordinate system.Equipotential contours of the four Rock Mass Fabric

0

10

20

30

40

50

60

70

0.01 0.1 1 10 100 1000

FQ

FRMR

F_RMR measured

F_RMR trend line

F_RCR dry

F_RCR flowing

r = 96.4%

Fig. 10. Correlation between measured rock mass indices FRMR and FQ.

S. Tzamos, A.I. Sofianos / International Journal of R494Indices are drawn in this system. Thus, the selection chartsscale together equivalent ratings used by the classicationsystems and offer determination of the Rock Mass FabricIndices by employing the most handy ratings or descrip-tions available by the users.Validation of the proposed rock mass fabric chart is

made to various constructed projects. The measured rockstructurediscontinuity conditions ratings of a systemwere used to predict the fabric indices of others. Thisachieved good accuracy may allow for the further use ofthe charts.The GSI value which is a function of Vb (or SR) and Jc

(or SCR) may be evaluated either by the pertinent charts orby a derived formula. Further, FRMR is related to FQ with aformula that resembles the already well-known correlationsbetween RMR and Q. Both formulas have high correlationcoefcients.The selection charts that were the main objective of this

research relating the four classication systems are applic-able in the following areas:

[4

[5

[7

[8

[9

[10[11Index (RMi). Tunnell Undergr Space Tech 1996;11(2):17588.

] Palmstrom A. Recent developments in rock support estimates by the

RMi. J Rock Mech Tunnell Techn 2000;6(1):119.

] Palmstrom A. Measurements of and correlations between block size

and rock quality designation. Tunnell Undergr Space Tech

2005;20(4):36277.416.

] Marinos PG, Hoek E. GSI: a geologically friendly tool for rock mass

strength estimation. In: Proceedings of the GeoEng2000, Lancaster,

PA. Melbourne: Technomic Publishers; 2000. p. 142246.

] Palmstrom A. Characterizing rock masses by the RMi for use in

practical rock engineering, part 1: the development of the Rock Mass[6]189236.

] Grimstad E, Barton N. Updating of the Q-system for NMT. In:

international symposium on sprayed concrete, Fagernes, Norway.

Oslo: Norwegian Concrete Association; 1993.

] Barton N. Some new Q-value correlations to assist in site

characterization and tunnel design. Int J Rock Mech Min Sci

2002;39(2):185216.

Hoek E. Strength of rock and rock masses. ISRM News J 1994;2(2):geological quality.

Therefore, the proposed charts provide a means forconsistent rock mass characterization, improve the utilityof the rock mass classication systems and may besuggested for use.

References

[1] Bieniawski ZT. Engineering classications of jointed rock masses.

Trans S Afr Inst Civ Eng 1973;15(12):33544.

[2] Bieniawski ZT. Engineering rock mass classication. New York:

Wiley Interscience; 1989.

[3] Barton NR, Lien R, Lunde J. Engineering classication of rock

masses for the design of tunnel support. Rock Mech 1974;6(4): In the design. Fabric indices represent the geologicalquality of the rock mass that together with themechanical parameters of the intact rock may be usedas input to rock mechanics models and calculations.

In characterization. They are helpful in the identicationof the features of the rock mass, offer quick measure-ment and description of these components giving themvalues or ratings according to various classicationsystems suggestions.

For the homogeneity of measured data in projects.Existing data in projects, rated using a certain classica-tion system, can be easily converted to another. Thisallows for the construction of databases of constructedunderground openings that may contain easily compar-able records offering wider experience from casehistories.

For translation between different geotechnical languages.Communication between different users is easier whenthe rating components are well dened and related tocommon understanding and language. Parameters ofone classication system can easily be converted toanother, together with the characterization description,allowing users to gain an improved mutual under-

k Mechanics & Mining Sciences 44 (2007) 477495] Hoek E, Kaiser PK, Bawden WF. Support of underground

excavations in hard rock. Rotterdam: Balkema; 1995 97p.

[12] Sonmez H, Ulusay R. Modications to the geological strength index

(GSI) and their applicability to stability of slopes. Int J Rock Mech

Min Sci 1999;36:74360.

[13] Cai M, Kaiser PK, Uno H, Tasaka Y, Minami M. Estimation of

rock mass deformation modulus and strength of jointed hard rock

masses using the GSI System. Int J Rock Mech Min Sci 2004;41(1):

319.

[14] Terzaghi K. In: Proctor RV, White T, editors. Rock defects and load

on tunnel support, rock tunneling with steel supports. Youngstown,

OH: Commercial Shearing Co; 1946. p. 1599.

[15] Sinha RS. Underground structuresdesign and instrumentation.

Amsterdam: Elsevier; 1989.

[16] Palmstrom A. /http://www.rockmass.netS.[17] ISRM. Standardization of laboratory, eld tests. Int J Rock Mech

Min Sci Geomech Abstr 1978;15:348.

[18] Hoek E. Practical rock engineering, /http://www.rockscience.comS.[20] Barton N, Bandis S, Shinas C. Engineering criterion of rock mass

strength. In: Proceedings of the fourth Hellenic conference on

geotechnical and geo-environmental engineering, vol. 1. Athens:

Technical Chamber of Greece & Hellenic Society of Soil Mechanics

and Foundation Engineering; 2001. p. 11522 [in Greek].

[21] Basarir H, Ozsan A, Karakus M. Analysis of support requirements

for a shallow diversion tunnel at Guledar dam site, Turkey. Eng Geol

2005;81:13145.

[22] Justo J, Justo E, Durand P, Azanon J. The foundation of a 40-storey

tower in jointed basalt. Int J Rock Mech Min Sci 2006;43:26781.

[23] Dalgic- S. A comparison of predicted and actual tunnel behaviour in

the Istanbul Metro, Turkey. Eng Geol 2002;63:6983.

[24] Dalgic- S. Tunneling in fault zones, Tuzla tunnel, Turkey. Tunnell

Undergr Space Tech 2003;18(5):45365.

[25] Dalgic- S. The inuence of weak rocks on excavation and support of

the Beykoz Tunnel, Turkey. Eng Geol 2000;58:13748.

[26] Polishook B, Flexer A. Assessment of chalk rock mass in excavations.

Bull Eng Geol Environ 1998;57:14550.

[27] Pells P. Developments in the design of tunnels and caverns in the

Triassic rocks of the Sydney region. Int J Rock Mech Min Sci

2002;39:56987.

[28] Anbalagan R, Singh B, Bhargava P. Half tunnels along hill roads of

Himalayaan innovative approach. Tunnell Undergr Space Tech

2003;18(4):4119.

[29] Goel RK, Jethwa JL, Paithankar AG. Indian experiences with Q and

RMR systems. Tunnell Undergr Space Tech 1995;10(1):97109.

ARTICLE IN PRESSS. Tzamos, A.I. Sofianos / International Journal of Rock Mechanics & Mining Sciences 44 (2007) 477495 495

A correlation of four rock mass classification systems through their fabric indicesIntroductionRock mass fabric indices componentsRock structure componentDiscontinuity conditions component

Common base for the Rock Mass Fabric IndicesBlock size componentJoint conditions componentCommon base for all Rock Mass Fabric Indices

ApplicationsConclusionsReferences