OTIC FILE COPY
IECHNICAL
REPORT GL-79-19
TUNNEL DESIGN BY ROCK MASS CLASSIFICATIONS by
Z. T. Bieniawski
D-A219
Pennsylvania State University Mineral Engineering Department University Park, Pennsylvania 16802
DTIC ELECTE MAR28
19
January 1990
Update
Technical Report GL-79-19
Approved
For Public Re;tas,,
Distribution Unlimited
IV
Prepared for
DEPARTMENT OF TH
ARMY
US Army Corps of Engineers Washington, DC 20314-1000
Under
Contract Nos. DACW39-78-M-3314 and DACW39-84-M-1462
Geotechnical Laboratory US Army Engineer Waterways Experiment Station T3909 Halls Ferry Road, Vicksburg, Mississippi 39180-6199 Monitored by
Unclassified SECURITY CLASSIFICATION
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REPORT DOCUMENTATION REPORT SECURITY CLASSIFICATION
la
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reverse
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Army
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INSTRUMENT IDENTIFICATION NUMBER
PROCUREMENT
(If applicable)
Engineers
DACW39-78-M-3314 DACW39-84-M-1462
ADDRESS (City, State, and ZIP Code)
10 SOURCE OF FUNDING NUMBERS PROJECT
PROGRAM
ELEMENT NO. Washington, TITLE
WORK UNIT ACCESSION NO.
TASK
NO.
NO.
20314-1000
DC
(Include Security Classification)
Tunnel 12
GL-79-19
39180-6199
MS
Vicksburg,
16802
PA
Report
,,, Sta e, nd Z/PCode) Halls Ferry Road
3909
Park,
distribution
7a NAME OF MONITORING ORGANIZATION USAEWES Geotechnical Laboratory
(If applicable)
6c. ADDRESS (City, tate, t ate, and ZIP Code)
University
release;
MONITORING ORGANIZATION REPORT NUMBER(S)
Technical
6a. NAME OF PERFORMING ORGANIZATION
public
unlimited
Design
by Rock
Mass
Classifications
PERSONAL AUTHOR(S) Z. T.
Bieniawski,
13a. TYPE OF REPORT Reprinted January
1990
13b. TIME COVERED TO_ FROM
16. SUPPLEMENTARY NOTATION Available
from National
Technical
14. DATE OF REPORT (Year, onth, ay)
Information
Service,
5285
Port
22161
VA
COSATI CODES FIELD
18 SUBJECT TERMS (Continue on reverse if ecessary an
SUB-GROUP
GROUP
Classifications'
Engineering
Construction Design
Park
systems.
comparison rcak
load
Classification. guidelines with
are
case
the
and
the
given
history,
design
is
made
method for an
and
Rock
that
the
current
for
improved
In
15
Springfield,
the
rock
tunnels.
current
order
design
to accomplish
design the
DO Form 1473, JUN 86
the
of
of
may
few areas
the
rock
mass
lead
to
that would
rock
mass
based
RSR Concept,
three
are
on
identified
classical
the
the
Using
practice
classification the
classification
described 4-n
methods.
design
Tunnels
Rocks
on
the
masses,
Rock mechanics,
design
overdesign
ensure
are
various
systems
current
the
three
practice
by
an
of support, of
where more
actual
it
comparing
It
systems.
construction
Geomechanic detail' and
and
safe
research
is
recommendaand
more
would
practice,
main
20 DISTRIBUTION/AVAILABILITY OF ABSTRACT (2 UNCLASSIFIED/UNLIMITED SAME AS RPT 22a. NAME OF RESPONSIBLE INDIVIDUAL
support
classification
made
procedures
Finally,
tunnel
tunnel
identify block number)
geology;-.Rock
project classification
selection based
app]ication
is
involving
made
economical
These
step-by-step
approaches
the
support
evaluation
tions
are
between the
Q-System.
concluded
benefit
Road,
River
19 ABSTRACT (Continue on reverse if necessary and identify by block number) This report discusses tunnel design procedures based on
tunnel
Royal
PAGE COUNT
.-
17.
Ter-aghi
15
1990
January
purpose
of
this
report,
namely
to
evaluate
tunnel
design
C(onn n,
21 ABSTRACT SECURITY CLASSIFICATION DTIC USERS
Unclassified
22b TELEPHONE (Include Area Code) Previous editions are obsolete.
22c. OFFICE SYMBOL
SECURITY CLASSIFICATION OF THIS PAGE
PrCIa'sif
Unclassified SECURITY CLASSIFICATION
OF THIS PAGE
REPORT DOCUMENTATION REPORT SECURITY CLASSIFICATION
la
Form Approved OM No. 0704-0188
PAGE Ib
RESTRICTIVE
MARKINGS
Unclassified
DISTRIBUTION /AVAILABILITY OF REPORT
2a. SECURITY CLASSIFICATION AUTHORITY
2b DECLASSIFICATION /DOWNGRADING
Approved
SCHEDULE
for
PERFORMING ORGANIZATION REPORT NUMBER(S)
See
6b
reverse
OFFICE SYMBOL
8a. NAME
US 8c
OF
FUNDING/SPONSORING
ORGANIZATION
Corps of
Army
8b. OFFICE SYMBOL
INSTRUMENT IDENTIFICATION NUMBER
PROCUREMENT
(If applicable)
Engineers
DACW39-78-M-3314 DACW39-84-M-1462
ADDRESS (City, State, and ZIP Code)
10 SOURCE OF FUNDING NUMBERS PROJECT
PROGRAM
ELEMENT NO. Washington, TITLE
WORK UNIT ACCESSION NO.
TASK
NO.
NO.
20314-1000
DC
(Include Security Classification)
Tunnel 12
GL-79-19
39180-6199
MS
Vicksburg,
16802
PA
Report
,,, Sta e, nd Z/PCode) Halls Ferry Road
3909
Park,
distribution
7a NAME OF MONITORING ORGANIZATION USAEWES Geotechnical Laboratory
(If applicable)
6c. ADDRESS (City, tate, t ate, and ZIP Code)
University
release;
MONITORING ORGANIZATION REPORT NUMBER(S)
Technical
6a. NAME OF PERFORMING ORGANIZATION
public
unlimited
Design
by Rock
Mass
Classifications
PERSONAL AUTHOR(S) Z. T.
Bieniawski,
13a. TYPE OF REPORT Reprinted January
1990
13b. TIME COVERED TO_ FROM
16. SUPPLEMENTARY NOTATION Available
from National
Technical
14. DATE OF REPORT (Year, onth, ay)
Information
Service,
5285
Port
22161
VA
COSATI CODES FIELD
18 SUBJECT TERMS (Continue on reverse if ecessary an
SUB-GROUP
GROUP
Classifications'
Engineering
Construction Design
Park
systems.
comparison rcak
load
Classification. guidelines with
are
case
the
and
the
given
history,
design
is
made
method for an
and
Rock
that
the
current
for
improved
In
15
Springfield,
the
rock
tunnels.
current
order
design
to accomplish
design the
DO Form 1473, JUN 86
the
of
of
may
few areas
the
rock
mass
lead
to
that would
rock
mass
based
RSR Concept,
three
are
on
identified
classical
the
the
Using
practice
classification the
classification
described 4-n
methods.
design
Tunnels
Rocks
on
the
masses,
Rock mechanics,
design
overdesign
ensure
are
various
systems
current
the
three
practice
by
an
of support, of
where more
actual
it
comparing
It
systems.
construction
Geomechanic detail' and
and
safe
research
is
recommendaand
more
would
practice,
main
20 DISTRIBUTION/AVAILABILITY OF ABSTRACT (2 UNCLASSIFIED/UNLIMITED SAME AS RPT 22a. NAME OF RESPONSIBLE INDIVIDUAL
support
classification
made
procedures
Finally,
tunnel
tunnel
identify block number)
geology;-.Rock
project classification
selection based
app]ication
is
involving
made
economical
These
step-by-step
approaches
the
support
evaluation
tions
are
between the
Q-System.
concluded
benefit
Road,
River
19 ABSTRACT (Continue on reverse if necessary and identify by block number) This report discusses tunnel design procedures based on
tunnel
Royal
PAGE COUNT
.-
17.
Ter-aghi
15
1990
January
purpose
of
this
report,
namely
to
evaluate
tunnel
design
C(onn n,
21 ABSTRACT SECURITY CLASSIFICATION DTIC USERS
Unclassified
22b TELEPHONE (Include Area Code) Previous editions are obsolete.
22c. OFFICE SYMBOL
SECURITY CLASSIFICATION OF THIS PAGE
PrCIa'sif
Unclassified SECURITY
6a.
CLASSIFICATION
NAME OF
Pennsylvania Department
19
ORGANIZATION.
PERFORMING State
University
Engineering
of Mineral
ABSTRACT
(Continued)
with respect
practices was
OF THIS PAGE
to
a.
Review
b.
Provide
c.
Evaluate
design
Identify
practical
d.
existing
classification
e. above results,
of work
scope
following
systems,
report
literture
reprinted through
for
practices steps
the on
in
rock
most useful
to
classification
of
selected
improved
design
the basis
leading
engineering.
needing immediate
of work was
accomplished
during
in
systems.
tunnel
history.
case
of safe
ard
more
tunnels.
requirements
and discussions
was
guide
systems
research
Recommend scope
classification
user's
economical
were
rock mass
defined:
are
presented
FY 89 during
1986as well
as
which
this
report
time
discussion
this
study,
and
the
procedures,
originally published
Bibliography of
attention.
recent
covering
dvelopmeats,
the
in
1979.
The
appropriate
given
in Appendix D,
added.
Unclassified SECURITY CLASSIFICATION OF THIS PAGE
PREFACE
report contains
This
Bieniawski
fo
Station
(WES) under
Banks,
performed
in FY 78
Laboratory
and Assistant
(GL),
The
Mr.
J. S. Huie, Chief, Rock Mechanics
Mr.
G. A. Nicholson, RMAG, assisted with
interpretation
appropriate,
of
1984).
case history
and
updated
in
This report,
The
reprinted
literature
Commander
COL Larry B.
through
th
th th
relating
to
tunnel
D. C.
of Dr.
(EGRMD),
monitored by
Group
(RMAG),
geological data Park main
th
River
EGRMD.
collection
and
Tunnel.
text revised, where in
developments
recent
design
in FY 90, adds
(covering the
period
Bibliography covering
th
1979
th
1986.
and Director
Fulton, EN.
direction
Applications
84 with
fo
Experiment
and DACW39-84-M-1462.
contract was
study of
FY
an appendix added
rock mass classifications
appropriate
was
th
report was
This
use
for
Funds
PA.
P. Sale and R. G. Ahlvin, Chief
and Messrs. J.
respectively, GL.
Chief,
under th
Waterways
Rock Mechanics Di vision
Chief, Engineering Geology and
Geotechnical
Army Engineer
US
Purchase Orders DACW39-78-M-3314
study was
This
th
provided by
study were
this
State University, University Park,
Pennsylvania
of The
Professor Z. T.
of an investigation by
results
the
of
WES
Technical
during
the preparation
Director
was
Dr.
of
this
report
W. Whalin.
Robert
Acoession For
NTIS
GRAMI
DTIC TAB
Unannounced Justifiaation
By
Distribution/ Availabl£t_ Codes
Avail and/or Dist
1/
Special
CONTENTS
Page
PREFACE................................................................... CONVERSION FACTORS, NON-SI TO SI (METRIC) UNITS OF MEASUREMENT............................................... INTRODUCTION....................................................
PART I: PART II:
CLASSIFICATION SYSTEMS
IN ROCK ENGINEERING ......................
Terzaghi's Rock Load Classification............................... Lauffer's Classification........................................... Deere's Rock Quality Designation.................................. RS Concept........................................................ Geomechanics Classification (RMR. ystem)...................... Th
10 11 13 16 23
Q-System...........................................................
34
GUIDE TO CLASSIFICATION PROCEDURES...........................
PART III:
Concept................................... th User's Guide fo RS User's Guide for the Geomechanics Classification .................. User's Guide for th Q-System...................................... Comparison of Procedures........................................... PART IV:
CASE HISTORY OF THE PARK RIVER TUNNEL.........................
Description of the Tunnel.......................................... Tunnel Geology..................................................... Geological Investigations....................................... Input Data fo Rock Mass Classifications.......................... Assessment of Rock Mass Conditions by Classifications .............. Tunnel Design Features............................................. Construction....................................................... Comparison of Support Recommendations............................. RESEARCH REQUIREMENTS...........................................
PART V: PART VI:
CONCLUSIONS AN
RECOMMENDATIONS...............................
Conclusions........................................................ Recommendations....................................................
44 44
45 46 47 49 49
50 55 56 56 60 60 62 64 64 64
REFERENCES...............................................................
66
BIBLIOGRAPHY.............................................................
70
TABLES
1-23
Page APPENDIX A:
TERZAGHI'S ROCK LOAD
APPENDIX B:
SUMMARY OF PROCEDURES FOR
TABLES ................................ ROCK
...............................................
MASS CLASSIFICATIONS
Classification-Rock Mass
Geomechanics
Rating
Q-System for
Rating
APPENDIX C:
CASE
Tunnel
RSR Concept ................................
Support ......................................
HISTORY DATA:
BI
(RMR)
System ........................................................... Rock Structur
Al
PARK RIVER TUNNEL ...................
B3 B9 B1
Cl
Cl-C2
TABLES FIGURES
Cl-C7
APPENDIX D:
RECENT DEVELOPMENTS
CLASSIFICATIONS
IN THE USE OF ROCK MASS
FOR TUNNEL DESIGN
(1979-1984)
Dl
CONVERSION FACTORS, NON-SI TO SI (METRIC) UNITS OF MEASUREMENT Non-SI units of measurement used in this report can be converted to SI units as follows:
Multiply
(metric)
To Obtain
By
feet
0.3048
metres
gallons per minute
3.785412
cubic decimetres per minute
inches
2.54
centimetres
kips (force) pe foot miles
square
(US statute)
pounds
(force)
pounds foot
(force) pe
square
pounds inch
(force) pe
square
pounds foot
(mass) per cubic
square feet
47.88026
kilopascals
1.609347
kilometres
4.448222
newtons
47.88026
6.894757
16.01846
0.09290304
pascals
kilopascals
kilograms per cubic metre
square metres
TUNNEL DESIGN
th
origin of
"The
writings
th
of
BY ROCK
MASS
science
ancient
classification -- the grouping of objects
recognition
approaches:
design
(Chicago, 1972).
of
characterization, engineering
practice.
in
are
analytical
techniques
as
are mainly
parameters
or processes
means
of
the
for
and for
encountered with
least used
the
lie
in
been developed
to
to
does
not
furnish
th
element method,
the analytical
high
input data as such
the boundary element
solutions, photoelasticity
or
analogue
assessing the
th
various
influence
yet acceptable
as
of
design
th
schemes;
design of
2.
The
observational
approach, of which'the
th
best
is based on observations and monitoring of
rock tunnels.
example,
construction
project proceeds.
th
support
ground
conditions.
that
flexible
support
itself,
rockbolts mass but
support
and
adjusted This
tunnel
is
allowing
approach
preferable
it
is
nevertheless
to
characteristics.
is
to
used to
deform
th
sufficiently
The problem with
based on
this
tunnel
the
philosophy
in
sound premise
ability
of
the rock
to
combination of
loosening
develop
go
changes
In practice,
excessive
to
you
th
meet
inherent
rigid one. prevent
to
support as
the
"build as
during construction
lining, utilizing
shotcrete
New Austrian Tunneling
and selecting or modifying
represents essentially
is
they are
practical engineering
th
behavior during
of
degree
Consequently,
comparing alternative
future not as
their
in the present
necessary
adequately explored.
the finite
useful
In view of the very
empirical.
is
three main
for
method is
since
rarely
form mathematical
simulation
methods
it
for
inability
the
conditions
the
and
difficulties
since some have
ground
method, closed
and the
reason
The
techniques themselves,
th
rock currently utilizes
analytical approach
the
primitive man."
INTRODUCTION
observational,
rock masses
sophistication, but
in
and the
U. S. Classification
th
to
of tunnels
the
Presidential
--
Society
analytical,
complex nature
Socal
to
dates
to
of
process
of similarities
Address
I:
goes back
th
however,
based thereon --
PART
The
classification
of
Greeks;
Prof. Robert R.
1.
CLASSIFICATIONS
in the rock
arching and self-
approach
is,
however,
that it
requires special
contractual provisions:
European practice error, bu
be
suitable fo
the
which they were evolved c-er many years of trial
fo
not easily adaptable
ar
these ma
th
to
an
established U.S. contracting
procedures.
3.
empirical
Th
previous projects
to
approach relates the
the
conditions anticipated at
empirical design is backed by
effectively
it ca
to exercising one's engineering judgment.
quantified, ar
of the design engineer
is no
to
tunnels
the
5.
compute accurately bu
In fact,
Europe,
South Africa,
form the backbone of the
to tunneling bu
Th
of some these
introduced over 40 years ago.
in the United States,
world:
even mining problems.
6.
to judge soundly."
widely employed in rock tunneling and most of
13-1
Australia,
East European countries. 21
only
the responsibility
rock mass classifications have been successfully applied
the
12
interact, even
most extensively used and the best known of
Th
throughout
no
taken into account;
the Terzaghi classification which wa
some
factors which
constructed at present in the United States make us
classification system. is
the
Rock mass classifications, which thus
empirical design approach, ar
This
recent paper:' "A good engineering
important since, to quote
those which cannot be
4.
If an
systematic approach to ground classification,
balanced design in which al
design is
proposed site.
utilize the valuable practical experience gained at many
projects, which is so helpful is particularly
experience encountered at
22
17
Canada,
Western
New Zealand, 18 Japan,'
USSR,
and
in
Some classification systems were applied
also to rock foundations,
23-24
rock slopes,
25
an
16
purpose of this
report is to evaluate
with respect to rock mass classification systems an
tunnel design practices
particularly
have been introduced in the recent years, have been tried ou number of tunneling projects, and have offered
on
those which
large
practical and acceptable
alternative to the classical Terzaghi classification of 1946.
CLASSIFICATION SYSTEMS IN ROCK ENGINEERING
PART II:
7.
statement made
Tunneling Conference
in 1972 during the
First Rapid Excavation an
is still appropriate fo
summarizing
th
present state
of tunneling technology:
many tunnels has, fo "Predicting support requirements fo years, been based on observation, experience and personal Barring judgment of -,.ose involved in tunnel construction. an unforeseen breakthrough in geophysical techniques for making tunnel sites investigations, th prediction of future tunnels will require the support requirements fo same approach."
Rock mass classification can, if fulfilling certain conditions, effectively combine fo
the
findings
providing 8.
from observation, experience, and engineering judgment
quantitative assessment of rock mass conditions.
rock mass classification ha
the following purposes
tunneling
in
application: a.
Divide
particular rock mass into groups of similar behavior.
b.
Provide group.
c.
planning an Facilitate th th design of excavations in rock by solution of real th yielding quantitative data required fo engineering problems.
d.
Provide
basis fo
understanding
common basis
persons concerned with
9. ha
the
These aims ca
fo
characteristics
th
effective communication among al tunneling project.
be fulfilled by ensuring that
classification system
following attributes:
a.
Simple, easily remembered, an
b.
Each term clear and the
c.
Only the most significant properties
d.
Based on measurable parameters that ca
understandable.
terminology used widely
relevant tests quickly and cheaply e.
of each
Based on
of
of rock masses included. be
in the
rating system that can weigh
the classification parameters.
acceptable.
determined by field.
the
relative
importance
f.
Functional by providing quantitative data for the design of tunnel support. General enough so that the same rock mass will possess the same basic classification regardless whether it is being used for foundation. slope, or tunnel, To date, many rock mass classification systems have been proposed,
10.
the better known of these being
Lauffer
(1958),g Deere
Bieniawski
the classification by Terzaghi
Wickham, Tiedemann, an
(1964),
and Barton, Lien, an
(1973),'
(1946),2
Skinner
Lunde (1974).1?
(1972),
These
classification systems will be discussed in detail while other classification; ca
found in the references.
be
11.
Th
classificat-ons named above were selected fo
si
discussion because of matter.
their specil
an
contributions
practical classification system introduced, ha States
for over 35 years
steel supports.
an
ha
Lauffer's classification
relevant
stand-up
simple an
from borings.
Th
the
active span in the
amount of tunnel
Skinner,5,6 wa
Th
is most
support. (RQD) index,
quality of rock core
concept of rock structure rating (RSR),
assigning classification ratings for weighing th
the
tunnel that
practical method of describing th
classification parameters.
the United
introduced th
introduced the rock quality designation
United States by Wickham, Tiedemann, an
Bieniawski 13 an
in
the first
based on work of Stini 26 wa
of tunneling since it
for determination of the type an
Deere's classification which is
time of
been dominant
subject
proved very successful in tunneling with
considerable step forward in the ar concept of the
the
to
rock load classification of Terzaghi,
classical
Thus, th
features
detailed
developed in the first system
the
relative
importance of
Geomechanics Classification proposed by
Q-System proposed by Barton, Lien, ard Lunde 12 were
developed independently (i
1973 an
1974, respectively),
an
both these
classifications provide quantitative data enabling the selection of modern tunnel ha
reinforcement measures
such as rockbolts and shotcrete.
been developed specifically fo
tunnels, while th
Classification, although also initially developed fo
Th
Q-System
Geomechanics tunnels,
has been
applied to rock slopes and foundations, ground rippability assessment, as well as
to mining problems.
Some comparisons have been made between the various classification
12.
systems. th
17
On
,18,23,27,28,29
railroad tunnel,30 which wa
construction of
long.
made by the author
during
18 ft* wide
miles
and 2.
--
characterized by highly varia ._. rock conditions
tunnel wa
This
detailed comparison wa
from very poor to very good.
one-year tunnel-monitoring
In addition,
program featuring 16 me tsuring stations enabled correlation between the classification ratings of rock conditions with the amount th
rate of face advance, and the support used.
opportunity fo
ideal
It
13. is,
means that
classification systems.
that the
the design of underground support
since rock mass classifications
selection of tunnel support.
ar
systems.
This
used as tunnel design methods, they provide for
In this connection, however,
remembered that tunnel support may be regarded as
it must be
the primary support
(otherwise known as the temporary support) or the permanent support concrete is
Primary support
lining).
invariably
is compl~ted.
(e.g.,
rockbolts,
installed close to the tunnel
(usually
shotcrete, or steel ribs)
face shortly after the
purpose is to ensure tunnel stability until
Its
The
"esign of underground excavations
they must be evaluated with respect to the guidelines that th
afforded an
given in Table 1.
is widely believed
large extent,
to
This project thus
comparison of the various
resu.ts of this comparison ar
jf rock movement,
excavation
the concrete
lining is installed. It should not be overlooked that
14.
be able to carry al
supports do no temporary an
the
the primary support may probably
load ever acting on the
deteriorate
tunnel.
easily and the traditional
permanent support
is losing
its meaning.
After all, modern
concept of the In some European
countries,
for example: Austria, Germany, Sweden, and Norway, only on
support
understood, generally
concrete
linings ar
stability into the
reasons bu
and shotcrete,
considered unnecessary if tunnel monitoring
stabili.ation of roc': movements. tunnels, while water
combination of rockbolts
tunnels ma
This
is the
case fo
highway and railroad
feature concrete linings, no
fo
strtctural
to reduce surface friction and to prevent water leakage
of factors for converting non-SI units of measurement
(metric) units
an
shows
rock.
table
kind of
presented on page 4.
to SI
15.
Consequently, th
concept of the primary an
use of the
the
permanent supports may well lead to overdesign cf tunnels since the so-called primary support ma
be
serves as an expensive
public
that is necessary an
al
cosmetic feature acting psychologically
confidence in the safety r' the
placing concrete engineering is
lining ma
be
lining only to bolster
The only justification
tunnel.
that since the current
still incomplete,
for
knowledge of rock tunnel
radical departure from the customary
However, the possibility of tunnel
methods of design may not be advisable.
overdesign should no
the concrete
be overlooked, and methods of minimizing
possibility, without jeopardizing tunnel safety, should be
this
constantly sought.
Terzaghi's Rock Load Classification
Since th
16.
Terzaghi both
purpose of this report is to evaluate other than the
classification system and since his classification is fully treated
in Proctor and White's book
repeated here.
an
However, for the sake of completeness an
historical importance, main features ar
in EM 1110-2-2901,
it will not be
because of its
of Terzaghi's rock load classification
given in Appendix A. Terzaghi's contribution lies
17.
in formulating, over 40 years ago,
first rational method of evaluating rock loads appropriate to th steel sets. ha
been th
during th
This was an
most commonily used system fo past 50 years.
classification fo
important development, because support by
estimating rock loads fo
suitable
for modern
design of steel sets
containing rock tunnel deformations
It must be emphasized, however, that while
is appropriate
for th
the
purpose fo
which it wa
steel-arch supported tunnels,
this
evolved, i.e.,
it is no
tunneling methods using shotcrete and rockbolts.
detailed studies, Cecil 32 concluded that Terzaghi's classification wa
so After to
general to permit an objective evaluation of rock quality and that it provided no quantitative information on
the properties
10
of rock masses.
Lauffer's Classification
Th
18.
1958
classification by Lauffer
earlier work on tunnel geology by Stini,26 wh
ha
foundation in the
it
is considered
"Austrian School" of tunneling and rock mechanics.
th
importance of structural defects in rock masses. stand-up time for
this
if
width of the
is th
than the
is less
noted that
tunnel or the distance tunnel width.
diagrammatically in Figure 2.
The stand-up
Lauffer's original
to
time is th
an increase
stand-up time.
This means, fo
small span may be
period of
It should be
time,
as
illustrated
classification is no longer
Lauffer's classification is that Figure span leads to
tunnel
in
support
Pacher.1
significance
Th
19.
the
number of times by other Austrian engineers,
Rabcewicz, Gosler, an
notably vo
shows ho
An active unsupported
from the
affect the stand-up
been modified
it ha
example,
drastic reduction in th
that while
successfully constructed
pilot tunnel having
full face in fair rock conditions,
large span opening in this same rock may prove impossible to support terms of th
th
Lauffer proposed that th
diagram in Figure 1.
number of factors ma
used since
father of
Stini emphasized
tunnel will stand unsupported after excavation.
time that
the
any active unsupported rock span is related to the various
rock mass classes as shown in th span
as
stand-up
time.
multiple drifts can enable
Only
in
system of smaller headings and benches or
large cross-section tunnel
to be
constructed in
such rczk conditions. 20.
disadvantage of
parameters, th
stand-up
Lauffer-type classification
time an
the
span, ar
rather much is demanded of practical experience. introduced the for
the
stand-up
determination of
influenced the
time an th
these
two
difficult to establish an
Nevertheless,
this concept
span as the two most relevant parameters
th
type an
development of more
is that
amount of tunnel support, an
this ha
recent rock mass classification systems.
11
13
0.
MIN
1O MIN
WK
HR
STA STAND-U ND-U
10 YR
MO
10
YR
TIME
Figure 1. Lauffer's relationship between active span an stand-up time for different classes of rock mass: very
good rock,
very poor
rock
.P
K,, TIME
0
.7
a. ORIENTATION OF TUNNEL AXIS
TIME
TIME
c. EXCAVATIONMETHO EXCAVATIONMETHO A.
... .
Figure
2.
TIME
b. FORMOF FORMOF CROSS SECTION4
SUPPORT METHOD
Factors influencing rock mass suitability during m mnln I,=m (schematically after Luffer
12
tunneling
Deere's Rock Quality Designation
proposed in 1964
Deere
21.
core recovery procedure which in. or greater
22.
RQ
Fo
recommends
incorporates only
determination, th
International Society fo
core size of at least NX diameter
th
been found
ha
(2.16 in.)
Rock Mechanics
drilled with double-
following relationship between the RQ
Th
engineering quality of th
proposed by Deere:
rock wa
Rock Quality Very Poor Poor Fair Good Excellent
RQD, Percent 25 25-50 50-75 75-90 90-100
23.
that ar
tunnel support.
barrel diamond drilling equipment. index an
modified
those pieces of core
This RQD has been widely used an
in length.
selection of
fo
very useful
quantitative index based on
Cording, Hendron, and Deere 33 attempted to relate
the RQ
index to
Terzaghi's rock load factor.
They found
supported tunnels but not fo
openings supported by
from Figure 3.
the opinion that Terzaghi's rock load concept concept
should be 24.
This supports
limited to tunnels
index in areas where th
fillings or weathered material.
25.
stability wa
of much value
rock tunnels as demonstrated
limitation of the RQ
on tunnel
rockbolts, as
Th
is evident
steel sets.
Merritt 35 found that the RQD could be
support requirements fo ou
supported by
reasonable correlation for steel-
in estimating
in Figure 4.
He pointed
joints contain
thin clay
influence of clay seams and fault gouge
discussed by Brekke and Howard.3
Although the RQ
is
quick and inexpensive index,
it ha
limitations by disregarding joint orientation, tightness, and gouge material.
Consequently, while it is it
is no
sufficient on it
practical practical parameter fo ow
to
core quality estimation,
provide an adequate description of
mass.
13
rock
VERY POOR
GOOD-
FAIR
POOR
EXCELL.
3.0
2.5
STEEL RIBS AND WOOD BLOCKING (LARGE DISPLACEMENTS, SMALL EXCAVATIONS) 2.0
1,-
__
_
__
1.5
LI.
1.0
ROCKBOLTS (SMALL DISPLA CEMENTS, LARGE EXCAVATIONS) 0.5
ol0.25 0.10
Q1W 25
50
RQD,
75
100
PERCENT
Figure 3. Comparison of roof support designs for steel rib-supported tunnels and for rock-bolted caverns (after Cording and Deere
14
100
41111
EXCELLENT
QUALITY ROCK HARD FEW JOINTS
SOLOAN,
FT CENTERS) PATTERN BOLTING
Go
LEGEND
60
(A
ItO
NO SUPPORT OCCASIONAL BOLTS
0.
PATTERN BOLTING
20
STEEL RIBS
_A-
-"_
POOR QUALITY CLOSELY ROCK
JOINTED &/OR WEATHERED
t0
40
30
20
60
s0
TUNNEL WIDTH. FT (AFTER MERRITT)
PATTERN BOLTING OR 4-6 CM 9OTCRErE
__ __.
__\\__\_
110
V//v//,
do
IS,
OR
CO
10
30
20
40
so
60
TUNNEL WIDTH. FT LEGEND
NONE TO OCCASIONAL BOLTING NONE TO OCCASIONAL RIBS, 5-
NOTE: FT CENTERS
SUPPORT DATA FROM IGNEOUS
AND METAMORPHIC
ROCKS WHERE REAL ROCK PRESSURES
PATTERN BOLTING 5-6 FT CENTERS LIGHT SETS 5-6 FT CENTERS
OR SWELLING/SQUEEZING DID No EXIST.
GROUND
PATTERN BOLTING 3-5 FT CENTERS FT CENTERS LIGHT TO MEDIUM SETS 4MEDIUM TO HEAVY CIRCULAR SETS 2-3 FT CENTERS, MAY BE IMPOSSIBLE TO DEVELOP MECHANICAL OR GROUTED ROCKBOLT ANCHORAGE
COMPARISON OF ROCK QUALITY SUPPORT CRITERIA, VARIOUS SOURCES
Figure 4.
Comparison of rock quality support criteria from various sources (after Merritt
15
RSR Concept
26
The Rock
prediction model, was Tiedemann,
and
Skinner.5.6
describing
th
quality of
It was
support. since
27
The
it
RQD
it was index
then give
which will
28
The
rating system individual
th
words,
as
well as
different aspects
29
of various
reviews
The
influencing
pattern
in
and
authors
pointed out
accurately define approximations
that,
th
and
could be
(b) direction
was
that
basis
papers
general
and
introduced of
th
In other
of case histories
dealing with
categories
geologic
in
were:
faults,
it
would be
others,
and
(a) rock type,
shears,
(b)
(dip and
and folds,
Some
of
collectively. possible
(f)
these
The
to
only general
construction parameters
were:
(c) method of excavation.
16
factors
(c) joint orientations
(e) major
but
of
parameters
others were considered
factors,
drive,
it
and span.
in tunneling.
joints),
The
time
system.
(g) weathering or alteration.
made.
of
stand-up
rock mass
classification parameters could
technical
in some instances,
above
Lauffer-type
decide on
classification
tunneling:
of
th
was
of weighted values
geologic parameters
treated separately;
were
of
the sum
considered two
The
properties,
terms
it
thirdly,
determined on the
(d) type of discontinuities,
factors
tunnel,
books
(average spacing
rock material
in
of the various
mass behavior
parameters.
experience to
this
ground support
RSR Concept
rock
construction
of
in
system was
rating
This
incorporating many parameters
the RSR Concept
of
considered
Terzaghi's qualitative
unlike
quality;
core
This was
importance
relative
assessed.
to
an output
rock masses.
for
in a number of respects:
forward
input and an output unlike
an
ground
classification system proposed
classification
limited
main contribution
parameters
be
strike),
is
that
appropriate
1946.
relies on practical
classification that class,
rock mass
th
for selecting
classification
classification having
complete
in step
quantitative
was
secondly,
th
RSR Concept was
and
method fo
quantitative
presents
rock mass
complete
first
introduced by Terzaghi
unlike
joint
rock mass
in 1972 by Wickham,
United States
concept
The
that
firstly,
one;
th
in th
developed
ground-support-
(RSR) Concept,
Rating
Structure
(a) size of
30.
Skinner
Al into
th
three basic parameters, A, B, an
respectively), on the
above factors were grouped by Wickham, Tiedemann, an (Tables 2, 3, an
4,
relative
which in themselves were evaluations as to th
effect
These three
support requirements of various geological factors.
parameters were as follows: General appraisal
a. Parameter A.
th
basis of
Rock type origin (igneous, metamorphic,
(2)
Rock hardness
(3)
Geologic structure (massive, slightly faulted/folded, moderately faulted/folded, intensely faulted/folded).
direction of
(hard, medium, soft, decomposed).
(1)
Joint spacing.
(2)
Joint orientation (strike and dip).
(3)
Direction of tunnel drive. Effect of groundwater
(1)
Overall rock mass quality du
(2)
Joint condition
(3)
Amount of water inflow (i tunnel).
Th
RS
size of th
inflow is based on an
combined.
minute pe
foot of the
to parameters
gallons pe
value of any tunnel section is obtained by summarizing the each parameter.
rock mass with respect to its need fo tunnel.
taken into consideration as discussed below.
respect to the
(good, fair, poor).
weighted numerical values determined fo quality of th
sedimentary).
Effect of discontinuity pattern with basis of tunnel drive is on th
c. Parameter C.
th
is on
(1)
b. Parameter B.
31.
of rock structure
Th in
Since
This reflects
the
support regardless of
relation between RSR values and tunnel size is th
determination of respective ri
lesser amount of support wa
machine-bored tunnels than when excavated by drill an suggested that RSR values be adjusted fo given in Figure 5.
17
ratios
(RR),
expected for
blast methods, it wa
machine-bored tunnels in the manner
1o
II.
20
30
40
1.05
1.00
1.15
I.io
FACTOR
RSR ADJUSTMENT
5.
Figure
It
tunneling
should be noted that
th
original
th
RSR ratings
were
Tables
from
reference
2,3
and th
reproduced not
are
and
paper6 p u b l i s h e d
in 1974
changed
fo
RSR concept-adjustment
machine
32
1.20
two
later,
years
from
because the
latter paper represents
latest information available.
33
In order to correlate RSR values with actual support
concept of
the RR was
RSR determinations with
for correlating
90 percent of th
Since
the RR measure
was
history
case
chosen as
the water
table
as
size rib
the datum
used in
condition.
formula
spacing by the
46 would mean
used
for th
RR would
equivalent support. be
100
for
that
th
section
datum condition.
the same
is
RR value
have
(rib size
for determining
Using
the
tunnel
The
require
RR for
different weight
required
percent
same
support
18
as
the
theoretical
100.
Thus,
of the
size tunnels,
for
determined fo
this
support
although
or size of ribs fo
an unsupported tunnel would be
requiring the
in loose
tables provided in
obtained by dividing
However, different
ribs,
and spacing).
tunnel section was
required only 46
steel
loads
roof
theoretical spacing
study
common basis
supported with
actual spacing and multiplying the answer by
RR
having
the
to
required installations.
support
(datum condition).
given case
The
or
tunnels were
Rock Tunneling with I n Steel Supports, same
actual
theoretical
the
It was developed from Terzaghi's sand below
The purpose was
introduced.
installations,
the datum
zero
and would
condition.
total of 53 projects were
34
evaluated, bu
divided into typical geological sections, analyzed.
Th
RS
since each
tunnel wa
total of 190 tunnel sections were
and RR values were determined fo
each section, an
support installations were obtained from as-built drawings.
actual
The support wa
distributed as follows:
Sections with steel ribs
147
89.6%)
14
8.6%)
Sections with rockbolts Sections with shotcrete Total supported
1.6%)
Total unsupported
26
Total
35.
(100.0%)
16
sections
19
An empirical relationship wa
developed between RS
an
RR values,
namely: (RR
80)(RSR
30
8800
(Reference 6)
(RR
70)(RSR + 8)
6000
(Reference 5)
or
It was concluded
that rock structures with RSR values less than 19 would
require heavy support while those with ratings of 80 an
over would be
unsupported. 36.
RR basically defined an anticipated rock load by
Since th
considering th
load-carrying capacity of different sizes of steel ribs, th
RSR values were also expressed in terms of unit rock loads fo
various
sized
tunnels as given in Table 5. 37.
steel
ri
Th
prediction model wa
support.
structures and rockbolt
RS
developed primarily with respect to
Insufficient data were available to correlate rock
rockbolt or shotcrete support.
However, an appraisal of
requirements was made by considering rock loads with respect to th
tensile strength of th general approach:
bolt.
Th
authors pointed ou
it assumed that anchorage was
acted in tension only;
it
adjacent blocks or fo
an assumption of
di
no
allow either fo
19
that this wa
very
adequate and that all bolts interaction between
compression arch formed by th
bolts.
In addition, the
Nevertheless, the
tunnels.
rockbolts with
given fo
1-in.-diam
(ft)
24/W
rock load in 1,000 psf.
is the
38.
following relation wa
steel supported
working load of 24,000 lb:
Spacing
where
rock loads were developed fo
No correlation could be
shotcrete requirements,
found between geologic prediction an
so that the
following empirical relationship wa
suggested:
= 1 + __
or
1.25
RSR)
(65
__D
150
where t - shotcrete rock
in.
load
tunnel
39.
thickness,
diameter,
ft
Support requirement charts have been prepared that provide
of determining typical ground support systems based on th
prediction as
to
quality of rock structure through which the tunnel is to be driven.
Charts for
10-,
respectively.
24-ft-diam tunnels ar
an
20-,
Similar charts could be used fo
steel rib curves reflect typical sizes used fo Th
RS
means
curves
fo
rockbolts and shotcrete ar
based on assumptions an
were no
shown in Figures 6, 7, an other tunnel sizes. th
8,
The three
particular tunnel size.
dashed to emphasize that they ar
derived from case histories.
Th
charts ar
applicable to either circular or horseshoe-shaped tunnels of comparable widths. 40.
The author believes that the
for selecting steel ri
approaches, on
Concept is no
support for rock tunnels.
should no
reliable data used fo
apply
concept.
very useful method
As with an
concept beyond the
developing
recommended fo
However, because of
SR Concept is
Fo
range of sufficient an
this
selection of rockbolt an
its usefulness
fo
author prepared an input data sheet fo
steel ri
empirical
reason, the RS shotcrete support.
support determination, the
this classification system
20
(see
It
Appendix B).
that although th
should be noted
classification parameters were not explicitly stated by of
th
th
however, lead
needed will
input data
to
normally included
be
(e.g.,
lack of definitions
in
the proposers,
most
standard joint
or
faulted
survey;
folded rock) may
some confusion.
41.
A practical Consider
example
th
using
20-ft diam
featuring medium hard granite.
joints
are open.
tunnel
length.
The
to
perpendicular
(basic rock
type
to
and with
Table
From
2) in slightly
2:
ft
gal/min per
250
th
igneous
For
dip of 45
faulted
and th
ft
1000
deg
poor joint condition
20 to
B = 25
deg, parameter
and moderate water
From
th
Thus: 1.
kips/sq
RSR
A + B + C
20-ft-diam
for
ft
th
Table
tunnel
From
will
be 6H20
57
tunnel steel
From Figure
57
with RSR
at
ribs
flow, parameter
7, the support
(estimated rock load
6-ft spacing. I" DIAM
ROCKBOLTS
SHOTCRETE
V-f24 DIAM S~~ ROCKBOLTS-.,~.-
T'/'
5,
1.25
70
'~-
-0.5 604"
DIAM
50
1.
U
2.0
20
DATUM
3.0 (RIB
4.0
-_o
RATIO =100 )
10
RIB SPACING. FT FT BOLT SPACING. SHOTCRETE THICKNESS.
Figure 6.
RSR concept
support
21
chart
IN.
for
axis
Table 4:
12 requirements
of
and
of medium hardness
strike perpendicular
45
dip of
rock
rock, parameter A
faulted
blocky jointing with
drive against
B = 45,
slightly
the jointing.
Solution: For moderate
is
inflow
follows:
is
joint spacing
driven against
be
as
to be driven in a The
estimated water
tunnel will
The
is
RSR Concept
tunnel
strata
For A +
slightly
of the
definitions
l0-ft-diam tunnel
3:
I" D'AM
SHOTCRETE
70
ROCKBOLTS-,, =I~r
0.
1.0
125
161120 RIB ---
lo
Z1.5
oW3
2.
n3.0 -5.0
30
-6.0
-ATU
-7.
(RB RATIO
20
O0)
I-jO -C
/U
20--
'Z/
10
SPACING, FT2 BOLT SPACING, FT SHOTCRETE THICKNESS, '..
Figure 7.
RSR concept
support chart fo
:14:
I" DIAM
SHOTCRETE
ROCI(BOLTS
=.
t=
01-
20-ft-diam tunnel
-2
RIO
AM
10ROCKBOLTS
I' 6H
-.
-3.0
2:
30-
200 (RIB RATIO =100)
10
-I
RIB SPACING, FT BOLT SPACING FT SHOTCRETE THICKNESS,
Figure
8.
RS
Concept
charts
-support
22
IN.
for 24-ft-diam
tunnel
42 System was of
th
Geomechanics
The
developed by
rock masses,
field but
overall
Rock quality designacion (RQD).
c.
Spacing of discontinuities.
d.
Orientation
e.
Condition of discontinuities.
f.
Groundwater conditions.
The
Geomechanics
tunnel
which The
route
region
45. according
th
23
ratings
while
apply
is
features
ir.tial
in
shown Next,
th
Table
importance
6, Section A.
histories,
built-in
importance
the
to
allocated
are
indicating better
from 49
case histories
ratings were based on the
Classification, of structural
are more
or
are
less
the rock mass along
regions,
i.e.,
uniform within
determined for
field and entered onto
th
zones
each
th
in
region.
structural
each
standard input
data
Appendix B.
ar
has
in the
of
Skinner.
number
into
were determined
th
the Geomechanics
divided
rating
In
for the
important
ratings
higher
6.
in Table
five range
into
equally
importance
parameters,
the
author
worst conditions
th
rock mass,
six classification parameters
to
presented
not
from measurements
sheet, as
is
Classification
are
These
in th
measurable
intact rock material.
the various parameters
certain geological
above
of
grouped
conditions.
To
strength
are
ranges of
are
utilizes
discontinuities.
of
by Wickham, Tiedemann, and
44.
only
6, five parameters
investigated by stud'-s
which not
b.
different value
classification
from borings:
compressive
classification of
engineering
(RMR)
engineering applications,
for rock
Uniaxial
Since
rock mass
This
a.
of Table
Section
in 1973.
all of
can also be obtained
43.
values.
evolved
six parameters,
following
13
Rating
the Rock Mass
or
Classification
Bieniawski
especially
(RMR System)
Classifi-ation
Geomechanics
The
ratings
In this
evaluat ed since
ratings
safety
given
are assigned
this
factor.
respect,
the
each parameter typical
rather
classification, being based Furthermore,
for discontinuity
23
to
spacings
it
than
on case
should be noted
apply
to
the
that
rock masses
having three sets of discontinuities. nuities
are
importance ratings
yield
conservative
of th
ratings
basic
overall
assessment
is
listed in
rock mass
th
th
Once
th
are established,
Section
rating for
sets of disconti-
obtained.
classification parameters
five parameters
th
fo
th
present,
Thus, whcn only two
of Table
structural
to
summed
are
region under
consideration.
46 nuities
this
At
included by
is
Section B of Table
of discontinuity tunnel,
parameter
6.
th
basic
This
is
treated
depends
whether
and dip
Table
In
Skinner.
discontinuity adjustments
7, which th
rock mass
is
civil will
given
not
th
e.g.,
"value" of th
quantitative facilitate
terms
by Wickham,
an adjustment
at depth or
stress
should be
Tiedemann, and
For mining applications,
th
but
decision
or not, reference
engineering projects,
be called for such as
to
influence
application
in
To
favorable
suffice.
th
separately because
"favorable." are
of disconti-
dip
rating according
upon engineering
is based on studies
orientations
may
such as
orientations
case of
strike and
It will be noted that
foundation.
descriptions
to
step
"discontinuity orientation"
strike
th
of
adjusting
by qualitative
made
influence
orientation
or
slope,
th
stage,
fo other
in
change
stress .23
47 is
After
classified
th
adjustment
according to
(adjusted) rock mass rock mass
classes
48 mass
Next,
class
tunnels
stand-up (Figure
by
in
Section D of
relating
it
th
and chambers,
to
of Table 6, which groups
(RMR) into
groups
specific from
rock mass
five
of twenty
Table
output
th
discontinuity orientations,
Section
ratings
are
fo
ratings
th
gives
classes.
that th
Note
each.
problems.
of each
th
In
given
rock mass
rock
case
of
is
th
Geomechanics Classification
time of an unsupported rock span for
mass
final
practical meaning
engineering
th
th
rock
rating
9).
49
Longer
ment measures
in
stand-up
can be
accordance with Table
depth below surface
excavation.
times
Support
(i
situ stress),
load can be
achieved by selecting rock
8.
They
tunnel
size
determined as
24
depend and
on such shape,
follows:
reinforce-
factors
and
th
as
th
method of
44
Ulaw
(N
044
LI
41
a-I
0o
):: 0600
.4
4J Li.
u)
CD
i0dfS
>.
<2
-rdS P.J~
100-RMR
100 where
th
is
is
width and RMR
It
50 represent concrete full
the rock mass
structural
not
it
is
construction should provide
51
in
employed
Strength of
52
is
weak,
the rock
Finally, model
of
is
sample the
of
the
rock mass
convenient for
use
given in Table
9.
th
rock core
The
si
discussed below.
th
if
influence
th
use
of
and Miller,
compressive strength
reason
retrieved
is
that
from borings
of
The
rock
is
to
th
26
core
classification of realistic
but for
is
the
determined purpose
strength
determined
does not
and
classification is
well-known, point-load
and
contemplated.
the same
of rock material
index can be
material
small-scale
particularly
th
rock
rock material
sometimes
This
is
the
engineering
is
th
the behavior of
field of rock mechanics.
of th
rock material
the
both been subjected
th
rock mass.
classifying
strength
represents
believed that
the use
the uniaxial
tunneling machines
It
Deere
of
the rock mass.
of
rock material
is
for
standard laboratory procedures,
rock classification, recommended.
if
and only
Each of the
rock mass.
are widely spaced and
they have
in th
The uniaxial
accordance with
parameter
fo
jointed rock mass
necessary
since
rock, proposed by
53
is
strength limit
important
also
during
that no single
that knowledge
confining pressure,
same
geological processes. intact
intact rock
of
the highest
constitutes strength
agreement
material properties will
Under the
is
ensure
of rock movements.
recognizes
describe
classification
this
monitoring
that tunnel
describe satisfactorily
if the discontinuities
all,
mass.
recommended
to
However,
factors have different significance,
general
compressive strength After
purposes.
additional
rock material
intact
There
Hence,
support.
structural
Classification
Various they
together can
parameters
primary
and quantitatively
tunneling purposes.
tunnel
the
in Table
support measures given
check on stabilization
Geomechanics
The
or index can fully
taken
th
required for
stability
is
rock,
rating.
the permanent and not
is
density of the
that the
should be noted
lining
th
is
support load,
of
index
is
in the field on
require
any
special
in
preparation.
Using simple portable equipment,
compressed between tw its
diameter.
th
square of th
54.
a,,
index which ca
is
the
information on
an
(2.16-in.
th
rock material
strength
redson is that rock hardness,
Th
is no
geologist's personal
subjective to
past before th
now assess th
completeress, th
point-load strength
advent of th
rock strength
in th
field.
following hardness classification wa
opinion.
Fo
sake of
th
used in the past:
a.
Very soft rock. Material crumbles under firm blow with sharp en of geological pick and can be peeled of with knife.
b.
Soft rock. Material ca indentations 1/16 to 1/ blows.
c.
Medium hard rock. Material cannot be scraped or peeled with knife; hand-held specimen can be broken with th hammer en of geological pick with single firm blow.
d.
Hard rock. Hand-held specimen breaks with hammer en under more than on blow.
e.
Very hard rock. Specimen requires many blows with geological pick to break through intact material.
seen from th
rock, hardness ca
be
above
du
to
that fo
hammer.
compressive strength of more be meaningful
be scraped an peeled with knife; in show in th specimen with firm
the
However, fo
the difficulty
by scratching with
rock having th
uniaxial
psi, hardness
than
of distinguishing by th
various degrees of hardness.
In an
indirectly related to rock strength, th
27
of pick
to medium hard
lower ranges up
assessed from visual inspection an
knife and striking with
test" th
ratio of the
such that for standard NX core
resistance to indentation or scratching,
th
been employed in th
be
across
uniaxial compressive strength (c)
that on rock hardness.
to
quantitative parameter an
ca
result of fracture
close correlation exists
core diameter.
I.
index
In rock engineering,
which is defined as
It
fails as
= 24 I.
is preferable
It ha
core
percent) 38 between th
-20
point-load strength
diameter),
Th
point-load strength index is calculated as th
Th
applied load to th (to within
points.
piece of drill core is
ceases
"scratchability
case, hardness is only
relationship between th
uniaxial
compressive strength an in
product of hardness an
th
density being expressed
following formula:
th
log a.
0.00014 7R
3.16
where
y= dry unit weight, pc Schmidt hardness
(L-hammer)
Rock quality designation (ROD) This index has already been discussed in paragraphs 21 through 25.
55.
It
is used as
cient on
its
classification parameter, because although it is no ow
fo
found most useful
simple,
rock mass, th
in tunneling applications as
been employed extensively
support, ha is
full description of
to
index has been
selection of tunnel
guide fo
in the United States
reproducible wa
inexpensive, an
RQ
suffi-
and in Europe, an
assess th
quality of rock
core
Spacing of discontinuities The term discontinuity means al
56.
in the
rock mass
that ma
be
technically joints, bedding planes, minor faults,
or other surfaces of weakness.
behavior of
rock mass as
the strength of
reduction.
Fo
Th
behavior of discontinuities governs
whole.
example,
rock material with
weak rock mass.
separate parameter, because th
spacing of discontinuities
RQ from
(ISRM) ha
degree of such
high strength, bu
Spacing of discontinuities
index does not lend itself fo
single set of cores.
of discontinuity spacings proposed by th
Mechanics
the
presence of discontinuities reduces
Th
rock mass, and their spacing governs th
jointed, will yield
th
geological discontinuities present
intensely is
assessing
classification
International Society of Rock
been incorporated into the Geomechanics Classification
(Table 10).
Orientation of discontinuities 57.
Studies by Wickham, Tiedemann, and Skinner
have emphasized the
effect of discontinuity orientations on tunnel stability. Table 7,
In accordance with
qualitative assessment of favorability is preferred to more
elaborate systems fo
joint orientation and inclination effects.
28
Condition of uiscontinuities This parameter includes
58.
their continuity, the
is an
weathering of th
wall rock. in the discontinuity
important parameter characterizing th
Asperities that occur on joint
nuities.
surfaces
condition of disconti-
interlock,
clean and closed, and inhibit shear movement along th
surface.
Roughness asperities usually have
measured in terms of tenths of an inch an sized exposure of
discontinuity.
defined below (it should be
surfaces,
(distance between the surfaces),
Roughness or the ratire of the asperities
59.
ar
their opening or separation
infilling (gouge) material, an
surfaces
roughness of the discontinuity
surfaces
if th
discontinuity
base length and amplitude ar
readily apparent on
core-
applicable descriptive terms are
Th
stated if surfaces ar
stepped, undulating, or
planar):
a.
Very rough. Near vertical steps and ridges occur on discontinuity surface.
b.
Rough. Some ridge and side-angle steps ar evident; asperities clearly visible; ar an discontinuity surface feels very abrasive.
c.
Slightly rough. Asperities on the discontinuity surfaces ar distinguishable and can be felt.
d.
Smooth.
e.
Slickensided.
Surface appears smooth an
rock material an rock mass.
th
In the
fo
influences the extent to which
discontinuities separately affect th
discontinuity
case of tunnels,
continuous if its length is greater
Consequently,
touch.
Visual evidence of polishing exists.
Continuity of discontinuities
60
feels so to the
Lhe
the
behavior of th
is considered
fully
than the width of the tunnel.
continuity assessment, th
length of th
discontinuity
should be determined.
Separation or the distance between th
61.
controls the
th
extent to which
the
discontinuity
opposing surfaces ca
interlock as well as
amount of water that can flow through the discontinuity.
of interlocking,
strength of
th
the joint
In th
filling (gouge) controls entirely the
discontinuity.
As
the
separation decreases, the 29
surfaces
absence
shear asperities of
th
rock material contribute to th
along
nature of the
discontinuity
Note
Very tight:
b.
Tight:
c.
Moderately open:
d.
Open:
e.
Very wide: th
description of
Th
is given in millimeter
a.
that where
62.
filling material.
as
filling an
th
The shear strength
degree of separation,
filling materials, roughness of th
surfaces
be described as
Th
shear strength of joints.
discontinuity is, therefore, dependent on th
presence or absence of th
both th
rock wall tend to become more interlocked, an
surface walls, an
the separation of the
follows:
<0.1 mm
0.1-0.5 mm. 0.5-2.5 mm.
2.5-10 mm 10-25 mm
separation is more than 25 mm.,
th
discontinuity should
major discontinuity.
Th
infilling (gouge) has
a.
Depending on th thickness, the filling prevents the interlocking of th fracture asperities.
b.
It possesses its
two-fold influence:
ow characteristic properties, i.e., shear deformational characteristics. strength, permeability, an
following aspects should be
described:
type, thickness,
continuity, an
consistency. 63.
Weathering of the wall rock, i.e.,
discontinuity th
surfaces,
is classified as
th
rock constituting th
recommended by th
Task Committee of
American Society of Civil Engineers: a.
Unweathered. No visible signs are noted of weathering; fresh; crystals bright.
b.
Slightly weathered rock. Discontinuities ar stained or discolored and may contain thin filling of altered material. Discoloration ma extend into th discontinuity rock from th surfaces to distance of up to 20 percent of th discontinuity spacing.
c.
Moderately weathered rock. Slight discoloration extends from discontinuity spacing. Discontinuities ma contain filling of altered material. be Partial opening of grain boundaries ma observed. 30
rock
d.
Highly weathered rock. Discoloration extends throughout th rock, and th rock material is partly friable. The original texture of the rock ha mainly been preserved, but separation of th grains has occurred.
e.
Completely decomposed is that of preserved,
It should be noted that
weathered rock. The rock is totally discolored an in an friable condition. Th external appearance Internally, the rock texture is partly soil. but grains have completely separated.
the boundary between
of the uniaxial compressive strength an
material with the
rock an
soil
is defined in
terms
in terms of weathering.
no
strength equal to or above 15
ps
is considered as
rock.
Groundwater conditions In the case of tunnels,
64
the rate
of inflow of groundwater in
gallons per minute per 1,000 ft of the tunnel should be determined, general condition ca
be described as completely dry, damp, wet, dripping, an
If actual water pressure data ar
flowing. an
expressed in terms
pa
stress.
available, these should be
ratio of the water pressure
of th
the vertical stress
stated
to the major princi-
The latter can be either measured or determined from the
below surface, i.e., foot of
or
increases with depth at 1.
depth ps
pe
the depth below surface.
Applications 65.
The rock mass along the
structural regions,
and th
each structural region an
tunnel route is divided into
above classification parameters ar
entered onto the
number of determined for
standard input data sheet, as
enclosed in Appendix B. 66.
Th
advantage of th
Geomechanics Classification is that it is no
only applicable to rock tunnels bu This the
is
also to rock foundations
very useful feature that can assist with th
tunnel portals as well as allow estimates of the
foundations fo
such structures as bridges.
67.
In the
an
slopes. 25
design of slopes near deformability of
example, fo
Fo
railroad route involving tunnels and bridges, the Classification fo
24
output from th
highway or Geomechanics
slopes and foundations will be very useful. case of rock foundations, the
Geomechanics Classification ha
rock mass rating RM
been related 24 to the
deformation in the manner shown in Figure 10.
31
from th
in situ modulus of
,I wz
w
0(
wu
00~
co 00
(n<
00
4-
a)
,n-4
41
00
0n
(r
a,
llOS
Sd
c2
l.SN
44O.V~dl0~
In the case
68.
Table
the cohesion and friction of th
as
were based on
output
Geomechanics Classification
Section D of
These output values
rock mass.
validity of
Th
the rock slopes was
to
analyzed 35 slopes of which 20 ha
wh
is given in
the data compiled by Hoek and Bray.
output from th Steffen
of rock slopes, th
th
tested by
He used the Geo-
failed.
mechanics Classification to obtain the average values of cohesion and friction an
then calculated
Bray.
Th 69.
results In
safety factor based on slope design charts by Hoek an
the
given in Figure 11
spite of
show definite statistical
its versatility, the Geomechanics
considered sufficient to deal with al
tunnel construction.
th
rock conditions predicted by th
behavior of
the
Th
purpose of such
Like with
monitoring program during program would be
classification an
to
to check on
evaluate
th
adopted support measures.
practical example using the Geomechanics
70.
Classification is
tunnel stability problems.
other empirical methods, it should be backed by the
trends.
Classification is as
follows:
Consider slightly weathered quartzite in which 20-ft-span tunnel is to be driven. Th following classification parameters were determined: Item
1. 2. 3. 4.
Strength of rock material RQ Spacing of discontinuities Condition of discontinuities continuous joints slightly rough surfaces separation <1 mm highly weathered wall rock no gouge
5.
Ground water
6.
Orientation of joints
Rating
Value
12 17 20 12
22,000 psi 80-90% 1-3 ft
Moderate inflow Basic rock mass value Fair Final RM Rock Mass Class:
II
68 -5 63
good rock
From Figure 9, fo Output: RM unsupported span 63 an 20 ft, the stand-up time will be about month. From Table 8, recommended tunnel support is rockbolts in crown 10 ft long, spaced at ft with shotcrete thick and wire mesh. estimated as 3.7 106 psi. in.
From Figure 10,
33
the
rock mass modulus is
S T A B L E SLOPES
SLOPES
FAILED
033 I'.
0.6
0,7
0,8
0,9
1,0
1.2
1,1
1.3
1,3
FACTOR OF SAFETY
Frequency distribution of slope
Figure 11.
stability as predicted by Hoek's design charts fo th geomechanics system strength parameters (after Steffen 25 71.
th
It is
important that th
selection of th
that ar
output data.
represented by th
72.
Th
determines th
chart
For this purpose,
intercept of an RM stand-up time.
line with th
RM
actual RMR's are used
desired tunnel span
Alternatively, th
line with th
intercept of an RM
maximum span possible in
any larger span would result in the
intercept of th
th
for
series of near parallel lines in Figure 9.
with the top boundary line determines th rock mass;
is correctly applied
in Figure
line given
immediate roof collapse.
lower boundary line determines th
An
maximum
span that can stand unsupported indefinitely.
0-System
73.
Th
Q-System of rock mass classification wa
1974 by Barton, Lien, and Lunde, al
of
34
developed in Norway
Norwegian Geotechnical
in
Institute.
Its
12
development represented
of rock mass classifications
Scandinavia,
it
number of reasons:
fo
basis of an analysis by
on th
Th
(c) roughness of alteration or
design of tunnel
Q-System is based on
quality using si
it
(a) RQD,
an
is
supports.
numerical assessment of th
different parameters: the
system was proposed
th
quantitative classification system, an
is
subject
tunnel case histories from
some 20
engineering system enabling the 74
major contribution to th
rock mass
(b) number of joint sets,
most unfavorable joint or discontinuity, (d) degree of
filling along the weakest joint, (e) water
inflow, an
(f) stress condition. 75.
Th
above six parameters
the overall rock mass quality
grouped into three quotients to give
ar
follows:
as
RO in
Ja
SRF
where RQ
rock quality designation
Jn=
joint
set
Jr=
joint
roughness
number number
joint alteration number
joint water SRF
76.
meters ar
stress
reduction number
reduction number
In Tables
11-13,
interpreted as
overall structure of th of the
the numerical values of each of
follows.
Th
first tw
Th
quotient of th
parameters is said to be related to the Th
parameter
is
fifth parameter is
measure of:
as
the
"total
parameters represent
third an
(o
35
the th
sixth
(c) squeezing an
This sixth parameter is regarded
quotient of
parameters is regarded as describing the
measure
case of shear zones an
in competent rock, an
Th
th
fourth
measure of water pressure, while
incompetent rock.
stress" parameter.
th
interblock shear strength
(a) loosening load in th
clay bearing rock, (b) rock stress
swelling loads in plastic
above para-
rock mass, and their quotient is said to be
relative block size.
joints).
th
the fifth an
"active stress."
the
sixth
77 Jr,
The
and Ja,
orientation
they apply
to
is
The
dividing
th
called
tity
th
of both
that
th
th
is
implicit
th
to
th
This
purpose of wall
height
excavation support
ratio
(ESR.
diameter,
in th
support
tunnel
excavation.
size and
orientation, and been
parameters
J,
if joint
less
Jr and Ja,
joints.
unfavorable
most
th
than joint
the parameters,
classification would have
orientation
of
role
or th
span,
th
th
important
related
equivalent dimensions function
of
included,
had been
th
78
12
more
played
However,
general.
because
proposers
requirements
equivalent
th
dimension, which
excavation,
of the
by defining
is
obtained
excavation by
th
is by
quan-
Thus,
Equivalent dimension
span, diameter,
Excavation
or height, meter
ES 79 and
th
is
ESR
The degree
th
related to
as
safety demanded,
of
use
for which
th
excavation
is
follows: No.
Excavation category
A.
Temporary mine
B.
Vertical
2.5
section section
Permanent mine
openings,
for hydropower
tunnels
water
2.0 1.6
83
1.
25
1.0
73
(ex-
cluding high-pressure penstocks), pilot tunnels, ings
D.
for
rooms,
plants,
minor
tunnels,
access
E.
Power
or
and head-
large excavations
Storage
road
drifts,
water treatment highway surge
and rail-
chambers,
tunnels stations,
railroad
defense
major highway
tunnels,
chambers,
civil
portals,
intersections
F.
Underground tions,
nuclear
power
sta-
railroad stations,
factories.
36
0.8
of
cases
3-
openings
Rectangular/square
C.
ESR
shafts:
Circular
intended
80.
relationship between the
Th
is illustrated
in which 38
12
Support measures
numbering. in Tables
in Figure
14-18.
the equivalent
index
an
support
categories ar
dimension
shown by bo
that are appropriate to each category are listed
Since it wa
decided that bolting and shotcrete support
deserves most attention, case histories featuring steel ri
support, concrete
arch roofs, and piecast linings have been ignored. 81.
is determined from the equation:
The length of bolts
,1.15 B/ESR
where
is
82.
the excavation width. 38 support categories
Th
listed in Tables
14-17 have been
specified to give estimates of permanent roof support since they were based on roof support methods quoted in th
determination, either 83.
as
follows
increased to 5Q or ES
is
maximum limit fo
Th
case histories.
(see also Figure
an
the
time.
relationship between th
In Figure 15,
P'roof=
of joint sets
is
Th
recommendations thicker
1/3
less than three, the Jnl/2 Jr
shotcrete an
the large-scale
equation is expressed as
Q1
that while
the
support
excavations would generally incorporate
longer bolts, the bolt spacing an
support pressure would remain roughly the same.
This
Figure 16 in which roof support pressures range from of th
permanent
an
following equation:
proposers of the Q-System emphasized1 fo
rock mass quality
relationship between
th
2.
Proof
85.
2(ESR) Q0.4
(unsupported)
support pressure Proof is plotted from the
If the number
ESR.
13):
Figure 14 shows th
stand-up
increased to 1.
is
permanent unsupported spans can be obtained
Maximum span 84.
temporary support
Fo
theoretical
th
is supported by
to 20
ps
independent
span. 86.
When core
is unavailable,
joints per unit volume, in which th
th
RQ
is
estimated
number of joints pe
37
from the number of
meter fo
each joint
00
uj
00 02
00 W2
-0 02 0~~
00L
0-
NO
0-
so NZ
\
00
r~jUj
0r
0000> 0.7
-04
~~ IN.Hw
MNk~I
0
ZN1AfO
3±bNVI
038
~0
-4-
Lu
*0
-0
-L
(DL LL
0-
LL
Co
LL I1 - XL
oLIi
(D
00
R~
xa
N-
C
-<
_jLo
)::
U- I"
IzC
tDLJ0
:,
IiiN
U11-
Ljr~r
wc0
FJ00
4-)
oo*
>00 1.
0mN 0~~ o-
V4(1
U3)OdlS
NZdS
Ir39
41i
Eo
o0
00
W(r
__<
(i0
EL
504
0)
w~
F-
()
l)
X. tn
wzwmo
Ix
C.)
0z
I~ X,
Ir
1-
0:
<(
wi
.~
wi
)*~
~~
>0
>Z
1Z-
a>-
-~DbO
3V411
W>01In ZWI-<
dn-aNV.LS
wtrzw LLJ
40
Ti
0
000
ITo
S41
02
02
ot
Er
44
LL)
'-4
00 0
MfS~
.J
41(r
40 BLT
•TENDON
Prf
roof
a.
40
EXCAVATION
16
Figure
Design
support
FT
SPAN,
for roofs
pressures
of large
caverns (after Cording, Hendron, and Deere
set
added.
are
The
conversion
RQ
where J., represents
115
is
Jv
-3.3
j o i n t s pe
t o t a l number
th
rock masses
c u b i c meter
(RQD
10
for i% <4.5).
percent
87.
88
following
a.
Classify
b.
Choose
c.
Estimate
The
the
optimum
th
water
1:
2:
involved
rock mass quality.
dimensions
appropriate using
tunnel
in applying the Q-System:
excavation.
permanent
th
of
of
support.
as
Q-System is
9-in
(29.5
ft
span
known:
smooth, planar
J-
1.0
chlorite
ia
4.0
15
Joint se
are
relevant
example
following is
Joint set
steps
th
practical Consider
mass.
for clay-free
coatings
joints per
metre
smooth, undulating
Jr
slightly altered walls joints
per metre
42
follows:
in
phyllite
rock
Thus:
J,
+ 5
15
and RQD
115
3.3
J, - 50 percent
1J -4 Most unfavorable
Minor water
Jr/Ja
inflows:
1/4
1.0
JW
Uniaxial compressive strength of phyllite: Major principal stress:
a,
ar
40 MP
3 MPa Virgin stresses
Minor principal stress: Thus:
a, / a
an
MPa
a.
a,
50 x 1
Support Thus:
For
estimate:
B/ESR
3.1:
B
9 m,
13.3 3.1
ESR
(medium stress),
SR
1.0
(poor)
1.6
4.6 support category
21
Permanent support: untensioned rockbolts spaced m, bolt m, and shotcrete 2- cm thick (see Table 18, note 1) length 2. Temporary support: none
43
PART
89 design
tunnels
rock
classification, three most
promising:
Q-System.
in
this
GUIDE TO CLASSIFICATION PROCEDURES
main rock mass classification
The
of
III.
th
other rock mass
Accordingly,
section
for
Apart
from Terzaghi's
were
systems
classification, full guidelines
given in
are
be
the
summarized
For Terzaghi's
systems.
in
and
1110-2-290131
EM
to be
shown
Classification, and
Geomechanics
classification
three
in the
in use
step-by-step design procedures will
the
these
classification
th
RSR Concept,
currently
in Part II
fully described
were
systems
Appendix A.
Guide
User's
90
The RSR
United States suitable
for
in
Step
by Wickham,
selection of steel
determination of th
1.
three
Divide such
Tiedemann,
support
the proposed tunnel
economical conditions
change distinctly;
change
Complete
3.
Ste
5.
into
and 4.
geological regions, similar and
it
will not be
i.e.,
rock mass
support until that
is
new structural
distinguished.
classification
input
as
data worksheet,
given in
for each structural region.
4, determine the individual classification parameters A, and and their sum, which gives From
to
Tables
the RSR = A +
Step 4.
tunnel
2,
in Tables
geologically
type of support,
one
to
Appendix B, Ste
route
that each region would be
region can be
2.
listed
particularly
It requires
tunnels.
and
in th
developed
is
and Skinner,
for rock
parameters A,
would require
Step
Concept
ground support prediction model
Concept,
1973
the RSR
for
B + C.
Adjust the RSR value in accordance with Figure 5 if the tunnel is to be excavated by tunnel boring machine. Select tunnel
support requirement size,
tunnels are
for
th
in Figures 6,
applicable
tunnels. and
e.g., to
chart
20-,
for
the
and 24-ft-diam
and 8, respectively.
selected chart,
spacing corresponding and
for 10-,
These charts
both circular and horseshoe-shaped
From the
rockbolt
chart appropriate
shotcrete
to
th
determine
rib
type
RSR value.
Ignore curves
since
not
support
based on sufficient case history data.
44
the
they are
SteR 6.
Estimate th rock load from Table RR from th formula: (RR
Th th
stand-up time, th
modulus, an St
8800
Geomechanics Classification, which wa
Th
th
1.
theoretical
for the Geomechanics Classification
Bieniawski,13 enables determination of th span, the
30
th
values obtained are for comparison purposes between structural regions.
User's Guide
91.
80)(RSR
an
RMR, th
tunnel maximum unsupported
support requirements, th
cohesion an
friction of th
developed in 1973 by
in situ rock mass
rock masses.
Divide the proposed tunnel route into structural regions, such that each region would be geologically similar and would require one type of support.
Step 2.
Complete Appendix B, fo
Step 3.
From Table 6, determine th ratings of th six individual overall RMR value, classification parameters and th following th procedure outline in paragraphs 42 through 46 an
52
input data worksheet, as each structural region (see paragraph 44).
through 65.
St
4.
From Figure 9, determine th maximum unsupported rock span possible fo given RMR. If this span is smaller proposed tunnel, th than th span of th heading an bench or multidrift construction should be adopted (see paragraphs 71 an 72).
St
5.
From Figure 9, determine th stand-up time for the proposed tunnel span. tunnel falls below th If th lower If the stand-up limit line, no support will be required. time is not sufficient for the life of the tunnel, the appropriate support measures must be selected.
Step 6.
From Table 8, select th appropriate tunnel support measures an note that these represent th permanent support.
Step 7.
If foundation design is contemplated fo nearby structures, select from Figure 10 th in situ modulus of deformation of the rock mass (see paragraphs 66 an 67).
45
8.
St
Step 9.
If th rock slopes near the tunnel portals ar designed, select from Section of Table th and friction data (see paragraph
Consider monitoring program during the tunnel construction fo sections requiring special attention (see paragraph 69).
User's Guide
Th
92.
to be cohesion
for the 0-System
rock mass quality Q-System, which wa
1974 by Barton, Lien,
nd Lunde,1
enables
developed in Norway in
the design of rock support in
tunnels and large underground chambers. Step 1.
Divide th proposed tunnel route into structural regions, such that each region would be geologically similar an would require on type of support category.
2.
Complete classification input data worksheet, as given in Appendix B, fo each structural region.
St
Step 3.
Determine the ratings of th si classification parameters from Tables 11, 12, an 13 an calculate th value (see paragraph 75).
Step 4.
Select the excavation category from paragraph 79 an allocate the ESR.
Step 5.
From Figure 12, determine th support category fo value an tunnel span/ESR ratio. th
SteR 6.
From Tables 14 through 18, select th appropriate to th support category. of rockbolts from paragraph 81.
Step
7.
th
support measures Calculate th length
Th selected support measures ar fo the permanent support. Should it be required to determine the primary
support measures, consult paragraph 82. Step 8.
Fo comparison purposes, determine th from paragraph 85.
Step 9.
Fo
Fupport pressure
record purposes, from Figures 13 an 14 estimate th possible maximum unsupported span nd th stand-up time.
46
Comparison of Procedures
93 of
discussion
detailed
approach
Terzaghi's
exist between the
Q-value.
23
Scandinavian
total
cases,
28
in Figure
plotted
is
relationship
of
11
Rutledge
17
three
from which
shown
cation
other
it will be seen
and
documented case
that th
determined
in New
Zealand
the
classification systems:
RSR
0.77
RMR
(standard deviation
8.9)
RSR
13.3 log Q
(standard deviation
7.0)
comparison in Figures
References
12.4 46.5
of the
long
than
experience
comparison of systems
is
18,
27
23,
Although
believed that
one
but should conduct
stand-up
and 14
9, 13
more conservative
17
following
following correlations
9.4)
classification
results
44
(standard deviation
96
The
Europe.
log Q + 43
and th
97
Q
ln
different tunneling practice rock
RMR and
involving 68
13.5
is
is
comparisons
or
RMR
95 as
and 21
Canada, Australia,
States,
It
applicable:
recently the
case histories were analyzed
South African cases,
RMR
between
IV.
systems.
classification
three
in Part
if any relationships
consider here
from the United
histories are
to
88
between
comparisons
follows
three classifications,
each
70, and
in paragraphs 41,
are given
A correlation has been attempted between the Geomechanics
94. th
and th
for using
examples
selected case history, giving
of
however,
appropriate,
practical
application,
of
classification systems
three
the
convenience
For
time and
reveals
the maximum unsupported
that the Geomechanics
the Q-System,
which
is
in
should not
the
1.
by six
different
Other comparisons
are
made
in
and 29 comparisons necessarily
sensitivity
classification with another.
reflection of
tunneling.
given in Table
the above
Classifi-
in Scandinavia based on the generally excellent
the support recommendations
28
span,
analysis
This
are
interesting and useful,
rely on any
and
47
one classification
cross-check the findings
could enable
mass.
.t is
better
"feel"
for
the
system of one rock
oo
IA
GOOD
AW3A
Wood AW3A
Uc
xO0
xO
00
00 --
>0
-+
or
w0
04
.0
CY
0b (fl
0r
00 >.
))
-J
d. v)
cnt
V0
.M
z0W~
r4 0
02 WV4W ONI.LVW NOIILVJIAISSV-10 SOINVWH3biO3E
48
CASE HISTORY OF THE PARK RIVER TUNNEL
PART IV:
In order to demonstrate the potential of th
98
mass classifications
case history wa
Park
US
th
details of th
the current design practice were well documented,43
geological exploration an
even in situ stress measurements were conducted. 44
logs were available fo
construction an
involved th
selected because
This project wa
Army Corps of Engineers.
This
water tunnel constructed by th
in Hartford, Connecticut,
River Tunnel
an
selected.
tunnel design by rock
In addition, borehole
author visited th
Th
acquainted himself with
tunnel during
rock mass conditions before holing-
through took place.
Description of th
99.
function of the Park River
Th
conduct approximately
Connecticut River.
Th
completed tunnel ha
Park River to th
22-ft inside diameter an
intake and outlet shafts.
excavated
It wa
basalt rock at the maximum depth of 200 ft below the
through shale an surface.
(auxiliary conduit) Tunnel 45 is to
one-quarter of the maximum flow in th
some 9,100 ft between th
extends
Tunnel
The tunnel invert at the outlet shaft is 52 ft below th
invert with the
minimum rock
tunnel sloping at
rate approximately
thickness of approximately
50
in. pe
ft will remain above
intake
10 th
ft.
crown
excavation at the outlet. 100.
Th
22-ft-diam tunnel was machine bored an
precast reinforced concrete segments
in
thick.
alternative, th
initial design specified th
place reinforced
concrete
additional
in. being allowed to th
heavy structural support wa
minimum thickness of
cast-in-
excavation pa 22 in. giving th
line.
with
Thus, the minimum
nominal excavation size
expected with th
concrete liner stipulated as
thick. 101.
tunnel
drill and blast
This nominal excavation size would increase to 27.7 ft where
of 25.7 ft
in
th
liner as 14 in. (Plate 9a-21 of Reference 44
expected concrete thickness would be
22
Fo
lined throughout with
Temporary rock support was prescribed fo
in the case
of the construction by drilling an
49
entire length of
blasting.
Typical
the
support patterns anchors
(rockbolts fully resin bonded bu
4-1/2 ft with shotcrete
in
no
thick without wire mesh.
In tw
structural W8 102.
Th
fault zones, expected to be steel ring beams at
$23.25 million fo
ft with shotcrete
an
(1978
conventional
drill
ft
in
long,
considered. dollars) fo
machine boring with precast liners
up to $33.37 million fo
In poor ground
approximately 30
ft were
anticipated bid prices
ft long, spaced
11
tensioned),
condition, the bolt spacing would be between thick.
specified 1-1/8-in.-diam rock
(for 88 percent of the tunnel)
tunnel were
th
(or $1,880 pe
foot) and
and blast construction.
Tunnel Geology
103.
shown.
Th
In Figure 18,
longitudinal geological section of tunnel is
rocks along th
alignment ar
sandy red shales/siltstones
interrupted by
limited rock types near the basalt. the extent that many marker beds
of th
various 104.
primarily easterly dipping Triassic zone of basalt flows and some
Bedding is distinct an
often regular to
correlated between boreholes.
Descriptions
rock types are given in Table Cl, Appendix C.
Three main geological zones were distinguished along th
tunnel
route:43,45
105.
a.
Shale an
b.
Fractured rock zone 23 31 st 10 an
c.
Two fault zones, one near st st 89 50 an 95 50.
Bedding an
dicular to th
basalt zones, constituting
jointing ar
tunnel axis
90
deg.
20 de
Joints in the
57
50 an
other between
th
to south which is perpen-
west to east).
while th
tunnel.
seamy), between
generally north
(tunnel will ru
generally dipping between 10 an between 70 an
(very blocky an 10 (800 ft).
88 percent of th
joints ar
Th
bedding is
steeply dipping
shale have rough surfaces,
and many are
very thin and healed with calcite. 106.
piezometric of th
Groundwater level in th
levels measured prior to studies
bedrock wa
normally 14
tunnel.
50
to 17
indicated that th ft
above th
invert
al V#V
3NI-7
LLu
~7'~A~K~ '4A Q 7 7 Z '
CID
TX 2,--
000
LU
ccn
6iz
cc
Q.,j
CC
Z--
-4
Ct
-4
0-
ISN 13 'N0UVA313
51
N~ilvkv
3N/7
I-
LUC
,-,~-to
77 0n
lu8
00
C1
k~so --
cco <4
.-
3N1
Ho
52
3N17
H3IOI
LO~
-4
0n
+1
ujI
U 1SV~I
53o
Ii.A
-4
bN
404
0%
/IS d'O.V31
544
Geological
Explorations consisted of core borings, various
107.
boreholes, an
seismic
survey.
tests within th
Tests in boreholes included borehole
photography, pressure testing, piezometer installation, observation wells, an pump tests.
(18 were NX diam
(2.16 in.)
reach tunnel level. removal
Al
11 were 4-in. diam).
is given in Figure
joint orientations
110.
an
the
Cl,
field immediately upon
logged, classified, an
employed in 15 boreholes
tested.
to determine
rock structure. localities within th
within one-half diameter above th
tunnel,
crown to determine the
density, uniaxial compressive strength, triaxial strength, city, Poisson's ratio, water content, and joint strength.
The results ar
swelling an
involving 15 tests, bu
slaking, sonic velocity,
tabulated in Table C2
equipment malfunction.
132 psi.
Fo
th
Th
depth of 12
th
Eight tests
found to be 452+
is calculated
as
This gives the horizontal to vertical stress ratio as 3.4.
Rock Mass Classification
Input data to enable rock mass classification by th
Geomechanics Classification, an
through C7
Appendix C.
anticipated along th in
the vertical stress
ft
44
more because of
tw
measured horizontal stress wa
Input Data fo
112.
Appendix C.
only three yielded successful results.
could not be completed because of gage slipping, an
psi.
elasti-
In situ stress measurements were conducted in vertical boreholes
111.
13
no
Appendix C.
Core samples were selected from 21
crown, an
Ten boreholes di
cores were photographed in th
Borehole photography wa
109.
th
an
from the core barrel, and the core was
typical drill lo
near
from 29 borings were used to determine tunnel geology
Rock cores
108.
The data ar
tunnel route.
th
Q-System ar
presented fo
RS
Concept,
listed in Figures C2 each structural region
Station limits fo
each region ar
shown
Figure 18. 113.
It should be noted that all th
data entered on th
input sheets have been derived from the borings,
55
classification
including information on
discontinuity
orientation an
This wa
possible because borehole
borehole logging in
wa logging procedures. the data
spacing.
from the
However, considerable effort wa
geological report fo
th
usual core
to
required in extracting
classification purposes since
engineering geological information was not systematically summarized in the form of classification input work sheets.
Assessment of Rock Mass Conditions by Classifications
114. th
RS
Rock mass classifications
Concept, th
in accordance with th
Geomechanics Classification, an
performed in Tables 19,
20,
21,
an
22,
th
respectively, an
Terzaghi Method,
Q-System ar ar
summarized in
Table 23. 115.
options
Three different tunnel
sections were designed an
offered as bi
45.
1.
Drill and blast with reinforced variably thick cast-in-place liner designed to meet three ranges of rock loading.
2.
Machine excavation with
reinforced cast-in-place lining.
3.
Machine excavation with
reinforced precast lining.
Tunnel Design Features
116.
Based on th
geological information, th
design of th
recognizes the following features, with reference to th
tunnel
geological profile in
Figure 18:
a.
Nominal support (8,000 ft): good rock, best average conditions, RQD 80 percent, water inflow gpm per foot of tunnel.
b.
Heavy support (800 ft): st 23 10 to 31 tunnel Th 10. intersects an area of thin rock cover and thick overburden, and rock conditions at tunnel grade are described as very blocky and seamy. Th to 14 deg, rock is not tight, dipping an water inflows of gpm per foot of tunnel ar anticipated.
56
C.
117.
50 93 50 to 95 st Steel support in fault zones (300 ft): to Broken rock is assumed du an 00 00 to 57 56 faulting, dipping between 20 an 60 deg, and low RQD of Pressure tests showed water inflows of 15-20 gpm 30 percent. foot of tunnel. pe summarized in Table 19.
The above rock conditions ar
designers believed (Reference 43,
p. 21)
that the actual conditions would
best average conditions in most of
exceed th
excavation,
tunnel.
th
rock load factors were expected to be
th
50 percent
in the major portion of
118.
Geologic conditions at
drill and blast
than to
lining, th
th
on
year before
reduced by as much as
tunnel grade were considered suitable Because of th
installed.
city
th
tunnel would stand up
drill and blast
lining wa
for
immediate
tunnel would drain less water under
tunnel would.
permanent
machine
Fo
tunnel.
th
machine boring accompanied by precast tunnel lining.
installation of
Th
Machine excavation would
also cause less vibrations. 119.
Th
conditions ar
envisaged tunnel designs fo shown in Figure 19.
(temporary) support and th
presented in Figure 19a. Fo
machine 120.
details of th
Th
As
operation, the
th
The basic design wa
tunnel will be
design of th
recommended primary
drill and blast
final lining fo
tunneling, liner details ar
three ground
each of th
based on
construction are Terzaghi Method.
th
given in Figure 19b.
completely full with water when in
tunnel liner assumed
pressure of 15 ps
for
contact grouting, which would ensure that the liner remains in compression
under net internal load conditions. Fo
purposes of analyzing stresses
subgrade reaction of 1,000 kc 121.
Tunnel
Grouting wa
required for the full ring.
in the concrete
(580 pcf)
instrumentation wa
fo
th
coefficient of
liners,
rock wa
assumed.
planned to provide fo
design verifi-
cation, future design applications, and monitoring of construction effects. Te
test sections at
locations based on differing geologic
conditions were installed throughout th sections
consisted of
pore pressure
length of th
or design
tunnel.
These test
10 extensometers (MPBX's) installed from th
transducers, rockbolt load cells, convergence points,
surface and embedded strain gages installed within th sections have been arranged to provide th
57
tunnel.
surface, an
The test
greatest amount of data based on
C4 k,
-AI
00
A..A
I-4
4J
A7
58
8eckpcA~~q
darnVIp1
pe.~rd
7*0e
,~,re
TRANSVERSE
PRECAST LINER:
ALTERNATE
SCALE 1-
1'0
SCALE 1/4'
isvde f~ce
___
Le'n
of
precoit jeoflen0.3 b a . d , 7a
compressive .sfrenpA 2.5rthe-
Ib~ge A r / b t '
wqaech
Zedgj
of
C-C
JOINT DETAIL
SCALE 3% 1'0
b,.RECAST Figure
19.
LINER
(Sheet
59
of 2)
SO~poemmO oAr
procedure w~ill iave Ad tAe conojtruet,0a
care fully m'amitored duvr joho-se to Injure oflfOFMl ,'/e crojs sgcot, n.
TRANSVERSE
'0
/,n7er
L1
SECTION
DETAILS
REINFORCEMENT
TUNNEL SECTION
PRECAST LINER
preSSdCIJ iMrea.46t
the planned construction
precast
throughout th of th
designed fo
segments were
tunnel.
If the
Th
Since th
fo
major portion
th
instrumentation program indicated that higher strength particular section of the
have been modified by increasing th shape.
lining.
worst ground conditions but were used
th
tunnel, they were in effect overdesigned
units were needed fo
external
TBM with precast
schedule of
purpose of the
design could
tunnel, th
steel reinforcement, an
keeping th
instrumentation program wa
design assumptions, and to refine the procedures fo
same
to validate
future designs.
Construction
Th
122.
tunnel wa
completion of the wa 25
outlet shaft, approximately th
advanced using drill-and-blast excavation ft by 25
section, an
advanced upgrade from the outlet shaft.
ft
in cross section.
tunnel boring machine tunnel advance using th
th
shielded rotary hard-rock TB
shield of
the TBM.
(TBM) wa TB
U-shaped chamber about
assembled in th
began.
which cu
Th
form
of the tunnel
ft
After completion of the drill-and-blast
Th
excavated chamber
machine wa
24-ft diam bore.
consisted of four-segment precast concrete the tail
to
first 23
Upon
Dobbins
fully-
lining
Th
liner rings which were erected
segments were
in
in. thick.
Comparison of Support Recommendations
123.
ar
Th
compared
support recommendations based on four classification systems Table 23.
a.
Th
following main conclusions ma
be drawn:
Terzaghi Method recommended th Th most extensive support measures, which seem clearly excessive by comparison with the recommendations by the other three classification systems. Th reason fo this is three-fold: (1) the current permanent lining design does no account fully fo temporary the action of th support, which in itself ma be sufficient for the structural stability of the tunnel; (2) th original recommendations by Deere et al. were based on the 1969 technology, which is now much outdated; an (3) no is enough us made of the ability of the rock to support itself and th
recent progress in the
60
field of
rock mechanics, i.e., th us of monitoring to assess rock mass stability. Since the Terzaghi Method uses such qualitative rock mass descriptions as "blocky an seamy," this does not utilize fully al quantitative th information that is often available from site exploration program.
b.
Th RS Concept wa not sensitive enough fo the rock conditions encountered; its application is limited to temporary steel support design.
C.
Both th Geomechanics Classification an Q-System gave fairly similar recommendations, and any differences in support prediction by these two methods enabled th designer to exercise better engineering judgment.
61
PART V:
124.
tunnel
The
present
design practice
believed
that
and more
economical
a.
RESEARCH REQUIREMENTS
revealed
study has
number
which could benefit
If
tunnels,
better and
scription of the
systematic
rock mass
in accordance with th
th
for
in
would result
more
in the present
It
from further research.
improved tunnel design procedures, rock
of aspects
th
construction of
engineering
data
safe
following areas:
is
conditions
input
is
de-
geological
provided, e.g., listed
sheets
in
Appendix B.
b.
If there is better communication and understanding among al th persons concerned with tunneling project.
c.
If the current tunnel design practice, which
is based
th
on
is supplemented by the more classification systems, such as the
revised Terzaghi Method modern
rock mass
Geomechanics Concept.
Classification,
These
classification
quantitative
the
exclusion
results
d.
If th
of
action
primary
of
support)
th e.
safety
temporary support
the
is
of th
fully the
incorporated thickness
could be
generally
g.
for the
safer
If
reinforced concrete
construction
are
case
tunnels,
If
more
research
th
linings
is
well
other
th
of
reinforcement endangering
tunnels
are
conducted
as
comprehensive
the adopted
and
th
mesh linings
62
in
46
left unsupported.
stand-up
time
of
spans,
the predictions
systems.
in th
water conduits
variously supported rock
classification
the
for drill-and-blast
sometimes
into
to
tunnel-
so-called New
than possibly
confidence could be placed rock mass
design
and more economical
by shotcrete
even water
unsupported as more
into the
more
construction would be ensured.
However,
to
(otherwise known as
and the
tunnel
rock
out
(NATM), not only
design could be verified but
of
one
incorporated, similar
envisaged
Austrian Tunneling Method
th
No
be singled
tunnel.
monitoring program
f.
of
cross-check of th
instead,
If during the tunnel construction procedures
full use
could be greatly reduced without
the latter
RSR
aimed for.
the permanent lining,
of
make
the
investigations.
should necessarily
the others;
should be
systems
from site
data
classification system
th
the Q-System, and
from
h.
125.
If more carefully documented tunnel case histories ar compiled featuring comparisons between support designs based on different methods, better understanding of design concepts will be achieved.
item a. above means
investigation ha so
above requirements deserve further elaboration.
Some of th
that sometimes
parameters needed fo
time is
design.
would greatly simplify th 126.
requirements an
to
well compiled
needed by the rock engineer to extract the Th
worksheets
use of th
given in Appendix
input data collection.
better communication on
Fo
program is called fo
fo
even when a well-planned geological
been conducted, the data presentation is no
that much additional
Thus,
ensure that th
that th
tunneling project,
training
geologists understand th
engineers make
it clear as
to what
engineers'
is needed and why
design purposes. 127.
Th
constitutes
NATM technique ha study on
its
own.
number of possible It should be
interpretations an
reviewed in detail and compared
with the current tunnel design procedures. 128.
Th
concept of th
outdated in view of to
the overdesign of
temporary an
the current rock engineering
tunnels.
129.
suitable rock monitoring Th
technology an
The concept could be
endangering tunnel safety, because an backed by
permanent support appears quite leads
reexamined without
reduction in tunnel support can be program.
relationship between th
stand-up
requires verification from actual case histories
time an
field of rock tunneling.
63
th
rock span
in the United States, an
research program directed to this aspect would make the
its us
great
itribution in
PART VI
CONCLUSIONS
AND
RECOMMENDATIONS
Conclusions
130.
For
th
design
classification system,
th
tunnel-design
131. tunnel
There
132. sufficient
need for more
realistic
on th
to
information, both concerning
th
they constitute
most valuable
source
in
(steel
number
alternative
support) Method.
of areas
of
rock
given below.
are
easy
are not
rock mass
and economical
Terzaghi
research
recommendations
Case histories
latest
Concept, the Geomechanics
RSR
Q-System, offer
some
design, and
th
procedures based
is
th
rock tunnels,
as
such
Classification, and th
to
of
compile
to
due
geology
th
th
and
lack of
design,
and yet
of practical knowledge.
Recommendations
132.
Based on this
a.
study, the
The
current
th
approaches
systems
as
tunnel
following recommendations
design practices
advocated by
the Geomechanics
and the RSR Concept. all
these
systems
made:
supplemented by
should be
such rock mass
are
classification
th
Classification,
Q-System,
by
Tunnel support recommendations
should be
systematically
compared
on al
tunneling projects.
b.
Engineering geological tunneling purposes
th
data
greatly
worksheets facilitate
tunnel case
C.
of
fo in accordance with rock masses
given in Appendix B. more
effective
This would
documentation
of
histories.
training program engineers
description
should be compiled
for engineering
should be
initiated
geologists
to ensure
and tunnel
better
communication on tunneling projects.
d.
The of
principles
and potential
an observational
tunnel
investigated
as
other design
approaches.
th
design
systematic
64
of
NATM, as approach,
study and
the prime
should be
compared with
th
example
e.
Research should be
initiated into three areas:
(1)
Th
(2)
relationship bet.yeen th Th stand-up time an unsupported, as well as supported, rock spans.
(3'
Systematic documentation of tunnel case histories comparison of rock conditions, support design, an construction experience.
interaction of the temporary an measures.
65
permanent support
fo
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74
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.45)1
414 4) 4)30 +3 31' 0
.. 1.
4u
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v)
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04 44)
4)0
1. .1.43+
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;3
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41
v' 4'
cis V. 1'.
4S
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c) 4. 4)J'
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8.1
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V34 4-31 u4
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4-0.4 404
4)
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to
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to
0+
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4
.0433+-'00
+3 4(. 0+30
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00+3 il3 4 4) .0 4))
-4. -63+4)4
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j
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10'
06.3 1. ..
.. *4)
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r-.
-4.
4)0
4)
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v'
41.
dc4 ). m)
4) 0
004 04 w.3
02
U0cj
50
5
r.
u) a))0
0i
1)4 o-0 54)
v.0
02
4-.
0n
0-
.4
-4.0
01
(a
0
u. 00
)0
I
.4)
.4) 41
3-.
() o54).-a 14 4) to v)44 4)0 00I
U\
t(74)03
02
1
to
'33 31I t.-4
w. 4)
01-4
01--
..'060-.0-
-40-43Cr-
4)
02
rM 03aQ1'1 aD
-t-
...- 4) 0 0 -44 4)5 C'4 3+3 r_ 04)0
'.'
4) 2
0
0+
..
031' +
4,-44
))'
1. +1. v14 0k
54j
C0.10. r. 02
-443.
W3 4)
(d.~
.-
P.. 4)
*0--
4)
434 *-
43
'Ac
V%
~1
U)
4)
'.1 '-4 )&C
'-4
02
(Wu
a, 043
43
)
a2
.00
.0~
41 43
m1
1.
02
m+
a)14 4):
w-4
U'.
02
cc
r;
)L
u
02
0
e -4
)00
U' 0.
-4)
to
06
4)
I4)
v
N)
-l
4)
4'
'0
04 3
4
ON42t~
.L
4) 4)
f310
20
Table Rock Structure Rating
Parameter
Rock Structure Rating Parameter "A" General Area Geology Max, Value 30 Basic Rock Type Soft Hard Med.
Igneous Metamorphic
Geological Structure Decomp.
1 Massive
Sedimentary
Slightly
Moderately
Faulted or Folded
Faulted or Folded
Type
30
22
15
Type
27
20
13
Type
24
18
12
Type
19
15
10
Intensely Faulted or Folded
Table Parameter
Rock Structure Rating
56-
Rock Structure Rating
Parameter
Joint Pattern of' rive
U40-
32
"B"
-Direction
24
'Strike
U, 8-1
j2
______________________Mx
Axis Direction of Drive
both
0
16
24
THICKNESS
32
Very closely 2Closely
Against Dip
Dip of Prominent Joints* Dipping Dipping Vertical 11
jointed
Vertical
13
10
12
19
15
17
Ma.Vle4
4Lto
au
Axis
Direction of Drive Both
Dip of Prominent Joints* Dipping Vertical Flat
9
9 11.
Jointed
23
24
28
19
22
23
23
19
to blocky
30
32
36
25,
28
3D
28
24.
36
38
1.0
33
35
36
34.
28
43
1.5
37
4.0
4o0
38
34.
hiocky to, massive (
Fiat
With Dip
jointed
Moderately
Moerate
404
IN INCHES
Strike
_L to
acio10
JFw;
di i~
-~
2'
to, 50r
and vert ical
517 to 90 dew.
Table Rock Structure Rating
Parameter
Rock Structure Rating
Parameter "C"
Ground Water Joint Condition Max. Value 25 Su
Anticipated 13
Water
Inflow (gpm/1000')
Poor
25
22
18
15
23
19
11
15
11
21
16
12
10
8
18
14
10
None
22
18
Slight (<200 gpm)
19
Moderate (200-1000 gpm) Heavy (>1000 gpm)
Poor
Joint Condition* Good Poor
75
Fair
Fair
or altered;
45
44
Good
Joint condition:
of Parameters A + B
Good
12
tight or cemented; Fair
severely weathered,
slightly weathered
altered, or open.
c0
Ntl-
-
~\10
co
(n)
-0t--
H-
I'D
O7\ H-
HCMj
CMj (N
_z CQ
ON
00
H1
'0
w4P
-P-
cr
'0
LIN
cC)
ifN
co
HD
IV
-'
L\'00
C)
4-)
C)
\0
co
(n
UN'
co
CM
C;
co
t--
Cfl I;
aj
NN
t-
CO
H1
C)
CM CMj
'. CMj
CMj
L(N
N.
NN
CM
LtN
m'
mI"
m-
t-
ON (Y)
__-
--
(D aH)
Q)
cd E-4
.4
MN
s-_:
xZ
~
C!
fn
M
H\ZM
*H
>
C)
+'
HCMj
CMj
CMj
t-
CMj
t-
C;
m~
(Y
t-
-Y'
CM
-T
'0 -4
w
:j
4)'
:3c
C)
UN\
m'
CO
_-r
ON
\-
:T
.4
--
ON\
H-
CM
t-
t-
LI".
LCT
UN\
UN\
UN\
UN\
UN'
ON\
0
4
ff)
M'
t-
0
UN
U-\
.0
COj
\.
4C)
MI
ON -1
(Y~)
I"
\.0
\.0
LN Lr(N
'.\
(Y
UN
C;I.
\0
IIN
\D0
ONl
0
0N
'0
0\j
CMl
'0
01
LrN
-4
CM \10
t-
'0
Table
GEOMECHANICS CLASSIFICATION OF JOINTED ROCK MASSES
A.CLASSIFICATtO
PARAMETERS AND THEIR RATINGS
PARAMETER
RANGE& OF VALUES
Pd UWs
Stegh.on-od10 of
4-t10 UPS
100 250 MP
-250 UAPs
this low fange uniaxiat compressive teat.is preterred
1-2 Ula
15
Drill core quality ROO
90%- 100%
spacing of aiscorrlinuitios
.2
2Rating Coofo dsotniis
Rating inlw1e01
tnnel legt0 m
.1
Ground
Precssur
stes
____________
25 min
OR
OR -OR
Rating
0.0-0.1
Completely dry
Damp
15
10
60 mm
60 -20mml
mm thick OR-5ti separation 1-5m
Sf
og>5mtil
20
10
10-25
25- 125 litres/mn
og
hL
OR Seaton>5m eaain>m Continous
Continuous
litresImin
OR
OR
APs
25%
urteces.Slickensided0 surtaces
_____________
OR
Gerai conditions
Slighty rough
Sapertwof mm Highly weathered wells
Nnlrel
1 UPs
25%-50%
60 mm
SlgtyGouge Separation mm Slightly weatrhered velt
30
5-25 ...
1085
rougt Suttace
~~~~~Unweathered _ _____________ ____________
Ratio
20
13
Not
Wea
13
rn
0,6
ni
Very rough srae.OR Ntcontinuous No separation all rock
50%-75%
17
20
Codt~ dsotnts
25 -50
100UPS
42
75%.90%
20
Rating
50
12
Rating
water
-4 MPSa
strength__index
intact roak u~.M -&tell&iv
S.
ntloadFor
125 OR
-OR
0.5
0,2-05
0.1-02
OR Wet
OR
Flowing
Dripping
__
RATING ADJUSTMENT FOR JOINT ORIENTATIONS
Strike and dip
Ratings
Very
Fa,,ourable
rnnes
-2
Foundations
-2
Sl
-5
[Class
Fair
Untsnourabfle
nfverab
-10
.12
-7
-15
-25
-25
-50
-60
a.-a
20
ROCK MASS CLASSES DETERMINED FROM TOTAL RATINGS
100--S1
Rating
Description
80-61
I
rv good rock
e60-41
'i"' Good roc:
Fair rock
ock
Very poforrck
PC-
MEANING OF 14OCK MASS CLASSES
C'ansNor Avirai
standl
time
Cohehion ofmhe rock mass C,,cion
IV
it)
angie oft he roockmass
10 fters to, 15 mnpan -'00 lip -45'
scan
1i6mon~thsto,
100 35'
00 kPA 4Is
,Ieft for 5m soan
200 -300 kPa
25'
3,'
span
hoursfor
100 200 kF 25'
30minutes for mn pan 100 lps 15
"-)
mo
w0." 0,
oto-
14
C4-
-4
n0,
D,
a)
J-j>
rq
43
0~ 06
CCt
m-
x
4,go
oc
00
*00
00
~~4,
(n
ti)
a.O
\,O 4-',
z4-
a)-
0)
-40 a)
Hc
.0\ 0 4-) 'd 0)
1) 0)
0 4)
0D 4-J
-4
44
(
,
c-.i.
$4-'
4U)
4-4H
) 0 'C4-
cu
V) co
0)) .H
O4d ,OU)r
-4
0)H
cc
r.
ul
o,
-' 00
t-'
75
-0
0.
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'0 04 C.dr.)C
100
00 0"4 Hl
0-0
S.. >,
0d C)
L)
4-
,4 HO
u'
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..
0n
4.
d-
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r1-.
00
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at
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Cd
0)>)' 00) rddH
+'d0-I 41
4-'0O04
4J04
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00 C) 04-c'z0 >d P4
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4-
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P4~ 03
0+00
AO
dE
Pl
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+H04.-+. -H
)>U
H.S,
H 0.4d n
1-.
1',U Jn~CC00'U
0.Cd)r-'
0)~S 00)
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WHO-0)+
0d
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CE
)
9z-0 C .00 .4 iN 0W 0Cd-' Z0 4-) 4S.) 00) $)-. 01 -1-4
0)
a'C-..-
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4-3
cc'r4
.d r.
+
r-uI
mU
H-0H
O
>)
(nf~d UH~
0
4-'
4-)
H0 10 Cd5Z-4UH U)0
T3
4-C4-
00)
E-.
4-'
Dc r+.
H-
4co
4-; .O..O
Cd
00
c
Hto0
4.)
C.
COA :3
4-.
0) p00 u
.H
-14
4-)4-
>,d-
OH
-,A
4-
-:
4-4 +'O. -\ -4o
-'lU 00
))
A) 4-)
00'0 00
Cc ci
~~~
C,1~
U,
U) >1
,iU Cd--
41
0
*tH 00 C>
0(
4-'
0)C
4-
'i
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a)
0+
In -4
0U0
H0 .C0 4)00 bO-O 40
Table
of
Classification
Strength
Intact Rock
Uniaxial
Compressive
Strength
Description Very low Low
strength
strength
Medium
strength
High
strength
Very
high
lbf/in
MPa
Examples
150-3500
1-25
3500-7500
25-50
Coal,
7500-15000
50-100
Sandstone,
15000-30000
100-200
strength
>30000
Chalk,
rocksalt. siltstone,
Marble,
gabbro,
Table Classification for
Discontinuity
Moderately Close
Very close
of
>2
Wide
0.6
close
200
60
ft
to 600 mm to
200 mm
<60 mm
dolerite, basalt.
Rock Mass Grading
>6 ft
to
gneiss.
Spacing
Discontinuities
Very wide
shale.
10
Spacing Description
schist.
slate,
granite,
Quartzite,
>200
of Rock Types
to
ft
8 in. to in
to
<2
Solid
in.
Massive
ft
Blocky/seamy
in.
Fractured Crushed
and
shattered
Table 11 Q-System:
RQD, Jn,
Description and Ratings
Rock Quality Desimation Very poor
...............
(RQD)
0-25
Poor .....................
and Jr
Note:
(i)
25-50
Where RQD
is
reported or
Fair........................50-75
measured as 10 (including 0) a nominal value of 10 is
Good .....................
75-90
used to evaluate Q in
Excellent ................
90-100
(1). (ii)
RQD 100,
intervals of 5, i.e.
95, 90 etc.
are
sufficiently accurate. Joint
Massive, One
no or few joints
Set Number
(J
0.5-1.0
Note:
joint set ............
One
joint set plus random
Two
joint
sets
Two
joint
sets plus
(i) For
intersections use
Jn)
(3.0 (ii)
..........
For portals use
(2.0
random .................... Three joint
sets ........
Three
sets plus
joint
12
random .................. Four or more
joint sets,
random, heavily jointed, "sugar cube", etc .......
15
Crushed rock, earthlike..
20 Joint Roughness
Number
(a) Rock wall contact and
(Jr Note:
(b) Rock wall contact
(i) Ad 1. if the mean spacing of the relevant joint set
before 10 cms shear Discontinuous joints ....
is greater than
m.
Rough or irregular, undulating ............... Smooth, undulating .......
Note:
Slickensided, undulating Rough
1.5
Smooth, planar
..........
1.0 0.5
when sheared
crushed zone
enough
to
prevent
1.0
(nominal)
or
thick enough
rock wall
c o n t a c t ..................
Descriptions B to G refer
features, clay
prevent rock wall contact Sandy, gravelly
favorably orientated.
(iii)
to small scale features intermediate scale an
(c) No rock wall contact
minerals thick
slickensided joints
having lineation, provided the lineations are
1.5
Slickensided, planar ....
Zone containing
0.5 can be used for
planar
or irregular,
planar ...................
to
(ii) Jr
1.0 (nominal)
in that order.
Table 12 Description and Ratings
Q-System:
12
Joint Alteration Number
(J
Or
(approx.)
(a) Rock wall contact A.
B.
Tightly healed, hard, nonsoftening, impermeable filling i.e. quartz or epidote ............................
0.75
Unaltered joint walls, surface staining only ......................
1.0
(250-350)
Nonsoftening mineral coatings, sandy particles, clay-free disintegrated rock etc ...........................
2.0
(250-30
Silty-, or sandy-clay coatings, small clay-fraction (non-softening)
3.0
(200-25
()
C. Slightly altered joint walls.
D.
E. Softening or low friction clay
mineral coatings, i.e. kaolinite, mica. Also chlorite, talc, gypsum and graphite etc., and small quantities of swelling clays. (Discontinuous coatings, 1-2 mm or less in thickness) .................
4.0
(80-160)
4.0
(250-300)
softening clay mineral fillings in thicknes) .... (Continuous, <5
6.0
(160-240)
Medium or low over-consolidation, softening, clay mineral fillings. (continuous, <5 mm in thickness)...
8.0
(120-160)
(b) ock wall contact before 10 cms shear
F.
Sandy particles, clay-free disintegrated rock etc .............
G. Strongly over-consolidated, non-
H.
Swelling clay fillings, i.e. montmorillonite (Continuous, <5 mm in thicknes). Value of depends on percent of swelling clay-size particles, and access to water etc .......................
(c) K., L.,
M. N.
R.
(6°-120)
rock wall contact when sheared
Zones or bands of disintegrated or crushed rock and clay (see G., H., J. for description of clay condition) ................ .........
6.0, 8.0
or
8.0-12.0
(60-240)
Zones or bands of silty- or sandy clay,
clay fraction
(nonsoftening) .....................
P.,
8.0-12.0
Thick, continuous zones or bands of clay (see G., H., J. for description of clay condition) ..... Note:
(i) Values of (O)r are intended as an approximate guide to the mineralogical properties of the alteration products, if present.
5.0 10.0, 13.0
or
13.0-20.0
(60-240)
Table 13 Description and Ratings
Q-ystem:
SR
an
Jw
Stress Reduction Factor
(SRF) (a) Weakness zones intersecting excavation, which may cause loosening of rock mass when
Note:
(i) Reduce these values of SRF by 25-50% if
tunnel is excavated.
A.
Multiple occurrences of weakness zones containing clay or chemically d i s i n t e g r a t e d rock, very loose surrounding rock (any depth) .............
the relevant shear
the excavation.
B.
Single weakness zones containing clay, or chemically d i s i n t e g r a t e d rock (depth of excavat i o n <50 m) ........................................
5.0
C.
Single, weakness zones containing clay, or chemically disintegrated rock (depth of excavation '50 m) ........................................
2.5
D.
Multiple shear zones in competent rock (clay free), loose surrounding rock (any depth) .....
7.5
E.
Single shear zones in competent rock (clay free) (depth of excavation <50 m) ..............
5.0
F.
Single shear zones in competent rock (clay free) (depth of excavation >50 m) .............
2.5
Loose open joints, heavily jointed or "sugar cube" etc. (any depth) .........................
5.0
0.
zones only influence but do not intersect
10.0
(b) Competent rock, rock stress problems.
ac/oI
H.
Lo
stress, near surface..
>200
J.
Medium stress .............
200-10
K.
High stress, very tight structure (Usually favorable to stability, may be unfavorable to wall stability) ...............
L. M.
/aI >13 13-0.66
2.5
(1i) For strongly anisotropic stress field (if measured): when
1.
5 duce
10-5
Mild rock burst (massive rock) ........... ..........
5-2.5
Heavy rock burst (massive rock) ....................
<2.5
0.66-0.33
0.5-2.0
nd cc 0.6 on where: unconfined compression 0.6
0.33-0.16 <0.16
N. Mild squeezing rock pr essure ................... Heavy squeezing
10, reto
0.8 oc and 0.8 at; 10, rewhen a)/03 duce oc and to
5-10
strength, at tensile strength
10-20
and (point load), major and m n o r 03 principal
(c) Squeezing rock; plastic flow of incompetent influence of high rock rock under th pressures.
0.
a /O and
rock pre ssure ..................
5-10 (iii) Few case records
10-20
available where depth
(d) Swelling rock; chemical swelling activity depending on presence of water
is less than span
P.
Mild swelling rock pressure ....................
5-10
R.
Heavy swelling rock pressure ...................
10-15
width. Suggest SRF increase from 2.5 to for such cases (see H).
Joint Water Reduction Factor
Approx. water pressure (Jr)
A.
Dry excavations or minor inflow, i.e. I/min. locally ............................................
B.
Medium Inflow or pressure occasional outwash of joint fillings ..............................
C.
Large inflow or high p r e s s u r e in competent
D.
Large inflow or high pressure, considerable outwash of Joint fillings .....................
E. F.
with unfilled
(kg/cm Note:
1.0 0.66
<1
(i) Factors
1.0-2.5
measures
rock
joints .......... ........... ......
0.5
2.5-10.0
0.33
2.5-10.0
inflow or water pressure
with time ...................
Exceptionally high inflow or water pressure continuing without noticeable decay ............
(i)
0.2-0.1
'1(.0
0.1-0.05
>10.0
are
are installed.
Special problems caused by ice formation are
ny
at
Exceptionally high blasting, decaying
to
crude estimates. Increase Jw if drainage
consiored.
Table Q-System:
Rock M . e .
Support Measure. fo
"Esceptio-a/"
"Very Good," od "Good" Quality (Q Pange:
Support
Conditional Factors
CategIn
1.
1000-LOO 1000-400
2-
3:
000-00 10OO-100
5.
400-100 400-100
67-
400-00
8.
400-100 100-0
S100-40
,,a
100-40
12-
i00-i0
i3
4O-ic
14
4.0-10
SP
ESP ()
.. ...... ......
0.O1
0.01 '0.01 '0... 001
SPAN/ ESP 20-40
Support sb (utg) sb (utg) at (uts) ob (utg)
-----
---
30-60
0.05
12-30
ab (utg)
......
0.05
19-45
Sb (utg)
...... ......
Note (Tab.e .8)
46-80 65-1oo
0.05 0.05 0.25
30-65 48-88 8.5-19
sb (utg) sb (utg) ab (.tg)
--
---
*0
....
'00
....
>3C
'30
.... ....
0.25
14-30
B (utg) 2-3 B (utg) 1.5-2
---
>30
....
0.25
23-48
B (tg) 2-3 B (tg) 1.5-2a
---
B (tg) 2-3 (tg) 1.5-2
---
'30
!30
'30
....
+clm 0.25
....
--
40-72
*elm
2_I0
1..5 '1.5
1.5 01-5
-----
0.5
±iO '10 '10 Z0
--
215
0.5
'10
--
?15
5-1"
--...
15 B5
.... ....
ob (utg) (utg) 1,5-2
(utg) 1.5-2 m (utg) 1.5-2 .S 2-3 cm 9-23
15
'10
--
(uJg) 2.5-3.
0.5
15-40
<-... 1610-10 See note XII
Type of
......
-0-IO
kg/ca (pro.
"Extremely GCood,"
1000_10)12
(ts) 1.5-2
0, 00
(t)
I,
+e
1.5-2
-S (mr) 5-10 c. (utg) 1.5-2
1,
B (tg) 1.5-2
0, II.
B (t)
1.5-2
'S (r) 5-10
0.5
30-65
B (tg) 1.5-2
cla (tg) 1.5-2 .S (a) 10-15 c.
II
I, 00, IV I, V, VI
I.
V, VI
Auth-r,' e s t i a t e e of support. Insufficient case records available for reliable estimtior of support requirements. The type of support tO be i-el in categories to e will depend on the blasting technique. S.oth vall blasting ard thorough barring-doan my reaove the need or '!
upport,
ure
1nG. -*g Iua !.y rok relnfor.eu
blasting my
result in the need for single applications of ehetcrete. especially where tte exvatior height is Key to Support Tsbles IL-17 Bb spot bolting; B systematic boltotensoned, grouted, (tg; tensioned, (expsnding shell type for competent rocx masses, grouted post-tensioned in very poor el see not. ; ahotcrete, (r) mesh reinforced. cla chair link mesh, CA east concrete arch, (sr) ateBolt spacings a- given in metres (m,. Shotcrete, or cost concrete arch thIckmnet given in rentlaetres (Cot. tgh-wll
case records should differentiate categories I to e.
IV
Table 15 Q-System:
for Rock Masses
Support Measures
Conditional Factors
Support Category
Jr'
10-4
17
..
>30 Z10. -10
ESR
Kg/cm (approx.)
..
1.0
--
(m)
3.5-9
>6
--
>5
--
>10m
--
'10
(utg) (utg) 1-1.5 m (utg) 1-1.5 m +S 2-3 cm sb
1.0
7-15
(tg) 1-1.5 m +clm (utg) 1-1.5 clm
--
..
..
(tg'
1-1.5 m
+S 2-3 cm
I, III
I, 111
(utg) 1-1.5 m
<10 >20
...-
10-4
19
Note (Table 18)
2-3ca
>10
>5
Type of Support
SPAN/
ESR
--
<30
18
SPAN/
of "Fair" and "Poor" Quality
10-1)12
(Q Range:
+S 2-3 cm 12-29
1.0
<20
(tg) 1-2
I, 21, IV
(tg)1-1.5 m
I, II
+S (mr).10-15 cm +S (mr) 5-10 cm
20See note
XII
21
4-1
_0.75
>12.5
23
4-1
>10,
<30
4-1
24-
See note XII
1.5
4.5-11.5
>15
1.5
8-24
.... ..
.... .............. ...
18-46
1.5
(utg) 1 m cm
+S 2-3
(utg) I m cm 2.5-7.5 cm (utg) +S (mr) 2.5-5 cm (utg) (tg) 1-1.5
+S (mr) 10-15 cm
(tg) 1-1.5 m
+S (mr) 15-30 cm (tg) 1-1.5 10-15 cm
<30
-r. ae
I, II, IV
I, II, IV, VII
(utg) 1-1.5 +S (r) 5-10
<15
>30
I, V , VI
2.5-5 cm (utg) I m
----
--
....
2.1-6.5
1.5
>1.0
,30
-..
(tg) 1-2
+S (mr) 10-20 cm
---
'30
..
--
(tg) 1-2
+S (mr) 20-25 cm
10.75 >0.75 >1.0 <1.0
>10
24-52
1.0
<35
--.
12.5 -22
_35
....
10-4
+S (r)
--,rdi
t-
rr.,t.e
e''v-ta
,f >a;;tr"
I, V, VI I, If, IV
ru:renments.
16
Table Support M~easures for Rock Mdasses
Q-System:
Support Category 25
Conditional Factors RQ0!/J,, JxIJa
Q*
'10 1O
1.0-0.4
--
26
2.0-0-L
--
27
1.0-0...
--
SPAN/ ESR
(mn)
'0.5
--
-0.5 0.5
--
of
"Very Poor"
kg/cm2 (approx.)
SPAN! ESE (m)
2.25
1.5-4.2
2.25
---
2.25
1.0-0.4
15-38
I, ix X. xi
ViIl,
X.
I, ii,
(tg(
20-30 cm
XI
Ix
IV,
I,ii, ix
(tg(1Im
4-S m-) 15-20 cm (ax-) 0-100 cm
-CCA
ViII,
1, IV, V, Ix
(tg( 1 m
4-S m-) 30-40 cm
4-S (m-)
I, IX
I, Ix
4-S mr) 7.5-10 cm
'20
--
cm,
4-B (tg) 1m
2.25
X, xi
Vill,
(tg)
>20, '30
--
cm cm
aS (m-) 5-7.5 cm CCA 20-4.0 4-B tg) 1 m (m-) 10-20 cm
30
--
(m-)
(utg) Im
<12 28' See note XII
+ S (m-)
(tg) .1 +S (m-) 5-7.5 cm (utg) 2.5-5
6-18
12
--
Note (Table 18)
m- or cin
(utg) (utg) B- tg)
3.2-7.5
12
--
Type of Support
-B
12
)1
.-.
Quality (Q Range:
IV, ViII,
X, XI
4-B tg) 29-
>5
0.4-0.1
--
30
0.4-0.1
'0.25 '5.25 0.25
--
3.0
1.0-3.1
--
--
--
3.0
2.2-6
(tg) (m-)
--
(m-) (m-)
+-
cm
4-S m-) 5-7.5 cm 31
0.1-O.1
3.0
'1--
4-14.5
->1-5
L4.
'1.5
32
See note XII
0.4-o.1
--
,20 m
--
3.0
11-34
20 mn
--
estimats
of
supprrt.
Irnztfficiert caae
4-B tg(
mn
(tg( +s (m-) (tg(
10-60
4-S
cm
(m-) 20-40 cm CA (sr) 40-120 cm
-
i.j&hors'
(tg)
4-S m-) 5-12.5 cm (m-) 7.5-25 cm CCA 0-40 cm 4-B tg( 1 m CCA (sr) 30-50 cm
--
4-B (tg( la
records
aveL.able
fo
reliable
cm cm
2.5-5 cm
5-7.5 Im
B-
-(tg)
2-3 cm
(utg( (utg) (tg(
--
IX Ix Vill, X, XI Ix
IX IX,
XI
Vill, X, Xi
ii, III,
IV, ix, xi IV, IX, xi
IV, ViII,
X, XI
estimation of support requirements.
-X
4-
0,
H-
0
L-C
\
C'J
1I
$
2)
-f
L\
H-
H>
0 0
r-
I'DC:J
\J0v)0
-I
Ur-
fl
H>
U,
00 -1
C\J p.j0
H>
E-
uC
00
\10
9--7
\00
II
-IY&
H'f~ )CO
o0
P
0)
Lf
P.
CiL
00 m'-mC'-
00
0 0-CC\,-4'
uj
U)
0x
H>
tj
~C.0 uLi
u-
IP
Lr\
-4L-
'
HHI>
LfLE
LI\ %-4-'
HX
PH
Q)
)
ii-
)E
4*
Cq 0-
000
'p.
CDI
9
CD
w0
a)
III
I H~r-1
I
I
II
p.
4' C-
Lf\
'p
Lf\
00
II
-4 -4
U) VAA
\I
0C
-14
Id
41 CO Z
I
C CLI
') --
002
Ally
All
OC
1
1
1
1I 1
1
I
44
U)
')
4'
4'
0)
00
0
00
00
-r
4)
U) U)
i-CU
Table 18 Q-System:
I.
Supplementary Notes fo
Support Tables
cases of heavy rock bursting or "popping," tensioned bolts with Fo enlarged bearing plates often used, with spacing cf about 1 (occasionally down to 0.8 m). Final support when "popping" activity ceases.
II.
Several bolt lengths often used in same excavation, i.e.
3, 5 an
7 m.
III.
Several bolt lengths often used in same excavation, i.e.
2, 3 an
4 m.
IV.
V. VI.
VII.
VIII.
IX
X. XI.
Tensioned cable anchors often used to Typical spacing 2- m.
supplement bolt support pressures.
Several bolt lengths often used in some excavations, Tensioned cable anchors often used to Typical spacing 4-6 m.
i.e. 6, 8 an
10 m.
supplement bolt support pressures.
Several of th older generation power stations in this category employ systematic or spot bolting with areas of chain link mesh, an free span concrete arch roof (25-40 cm as permanent support. instance montmorillonite clay (with access Cases involving swelling, fo Room for expansion behind the support is used in cases of of water). Drainage measures ar heavy swelling. used where possible. Cases not involving
swelling clay or squeezing rock.
Cases involving squeezing rock. as permanent support.
Heavy rigid support is generally used
According to th authors' experience, in cases of swelling or squeezing, temporary support required before concrete (o shotcrete) arches th consist of bolting (tensioned shell-expansion type) if formed ma ar value of RQD/Jn is sufficiently high (i.e. >1.5), possibly combined th with shotcrete. If the rock mass is very heavily jointed or crushed (i.e. RQD/Jn 1.5, for example "sugar cube" shear zone in quartzite), then th temporary support ma consist of up to several applications of
shotcrete. Systematic bolting (tensioned) ma be added after casting concrete (or shotcrete) arch to reduce th uneven loading on th th concrete, bu it ma lo not be effective when RQD/Jn 1.5, or when of clay is present, unless th grouted bolts ar before tensioning. sufficient length of anchored bolt might also be obtained using quick setting resin anchors in these extremely poor quality rock-masses. Serious occurrences of swelling and/or squeezing rock may require that concrete arches ar th right to the face, Temporary support of the working face shield as temporary shuttering. ma also be required in these cases. XII.
Fo
reasons of
safety th
multiple drift method will
during excavation and supporting of roof arch. 28, 32, 35 (SPAN/ESR 15 only). XIII.
often be needed
Categories 16, 20, 24,
Multiple drift method usually needed during excavation and support of arch, walls an floor in cases of heavy squeezing. Category 38 (SPAN/ESR only). 10
CCC
r0
4.
*0
.c
II
u.
rC
4.4.40
-04.C4
00 r*CL
.t
0.~ o00
0.0
t0
4.00
00 cz
(a
04
co
*0 040
>4 .*
s/
.0~
OC
07.0
x.
H.
0 .0
0cc.
4-)
t-3
\04-'
0.. HH
.,
C\j
oc
00
-'s-
4-)
s-I
Q)
Q) U)
r.
5-4
ci
NM
4-'
CC
V)
CMj -0
4-'
(d
-j
s-
CM
NM
Ofr
r.0
(Y)4-
-4
.,0M)
-1 Cl)
-I V) U) U2
c.)-'(-)
Ca
Cd
-T
4-)
NM
Cj
ON
C) (n
a)
r+4
4-
CC)
0)
(V)
C) C)
rn
_z
00
U) Cf)
.11 4-' 0)
03
E--4 -4
4-'
4-
4-)
U)
H-
dt-4-
U) 'd
Q)C
Q) C:
I-q
\D
H)
a) C)
m0oc
W
Co
CQ
CC)-
-j
-:
0H'. 4-'0
)CJ~ aD~H)4-'
CM
-~
L'
4-) C)
4-' V) r)*-4
0~C
+~
)C
-4
x90
4-)9 r-
5-t
Id
(1)
4)
Q) 10
04-)
09
a),
II
He.4 Id
>,
-)
0lE40
Table 21
Rock Mass
Classifications fo
Park River Tunnel in
th
Accordance with the Geomechanics Classification
Parameter an Region
Best Average Region
Conditions Region
Worst Average Conditions 23+00 to 31+00 St
Fault Zones Region
Intact rock strength RQ
20
20
13
Discontinuity spacing
20
20
10
Discontinuity condition
20
22
10
Groundwater
10
In situ rating
75
79
Discontinuity orientation
-5
-5
RM
Good rock
Maximum span standan up time
55
at 2-1/2 months or 26 ft at ft
Poor rock 37
74 26
-10
-1
Good rock
70
26
47
ft at
18
ft at
Very poor rock 16
12 hr
ft
at 1/
hr
months
months Support
Note:
Locally bolts in roof 10 ft ft plus occaslong at sional mesh, shotcrete in. thick
For input data sheets,
se
Systematic bolts long at shotcrete thick with wire mesh 12
Appendix C.
ft ft in.
Ribs
at 2-1/2 ft
bolts 15 ft long at ft, shotcrete in. thick with wire mesh
4-3
4-)
rd
0) Lf\
00 S0
En2
LofU\
Lr\
Cj
Lr\ C
C\J
\\
CJ
"H ILI
S.
+1
Q)
4-,) -i0
Op
a)
co
4)
0204
02-0 0* 4-
)0H~+ 00-
4-) 0)
C)
03
0~U
4-4 cc \J
0)
to
H-
+0
>1
4-3
W~
*H
C\J
44
a,
\10
U'
H-
\4:
m+3c
$2C/
Q)
-)
0-
C~j
4-
HCJ'
4-
4-
EQF U3
4-)
Ii
4-
C)
3: 02)
E- *H
0~
uH
L\ 0 ON~
-)
0d
zxrI 0-
02
Cdl Hi
0
UN *-
-CM
+-)LtN0)
4-)*
a)
43
0P
>, S.)
0)
U)
C\
30
Hc
+3
Hd
C
4-
00
Pc
OH
Ho
0d'
2a
0
0)
a)ri4-4 5-4
+3+3
+Nw3, r4
0.f 4a
r4
00
02
+03 (1)
0);
C) 0)
.. CL
.3
.OC
oV
.r3
"00O
0G
0.0
1.
.10
.4
F,
C-1
(n
.000Z0
06
cc0
<0 -I
CC
0i SIV
40 cO..
'D
>0SA i-
nr~
I-
CAgo
APPENDIX A:
TERZAGHI
ROCK LOAD TABLES
Table Al Terzaghi's Rock Load Classification for Steel Arch-Supported Tunnels (Rock Load
Width
H
in Feet of Rock on Roof of Support in Tunnel With (feet) and Height
Than
Rock Condition
Hard and intact.
2.
Hard stratified or schistose.**
3. Massive,
moderately
Rock Load
Depth of More
(feet) at
1.5(B
))
in Feet
Zero
Remarks Light lining required only if spalling or porning occurs.
to 0.5B
Light support, mainly for protection against spalls. Load may change erratically from point to point.
to 0.25B
jointed.
4.
Moderately blocky and
5.
seamy. Very blocky and seamy.
6.
0.25B to 0.35(B +
u.35
.I10) (5
No side pressure.
Little or no side pressure.
1.10(B +
Considerable side pressure. Softening cffects of :eepage towards bottom of tunnel requires either continuous support for lower ends of ribs or circular ribs.
7. Squeezing rock,
(1.10 to 2.10) (B +
Heavy side pressure, invert
8.
Squeezlne rock, depth.
(2.10 to 4.50) (B +
9.
Swelling rock.
Up to 250 feet, irrespective of the value of (B Ht)
Completely crushed but chemically intact.
moder)te depth.
The roof of the tunnel
struts
required. Circular ribs are recommended. Circular ribs are required. In extreme cases use yielding support.
is assumed to be located below the water table.
permanently above the water table, the values given for types fifty percent.
to
If it is located
can be reduced by
Some of the most common rock formations contain layers of shale. In an unweathered state, real shales are no worse than other stratified rocks. is often However, the applied to firmly compacted clay sediments which have not yet acquired the properties of rock. cucn so-called shale may behave in tunnel like squeezing or even swelling rock. If rock formation consists of sequence of horizontal layers of sandstone or limestone and of immature shale, the excavation of the tunnel is commonly associated with gradual compression of the rock on both sides of the tunnel, involving downward movement of the roof. Furthermore, the relatively low resistance against slippage at the boundaries between the socalled shale and the rock is likely to reduce very considerably the capacity of the rock located above the roof to bridge. Hence, in such formations, the roof pressure may be as heavy as in very blocky and seamy rock.
A3
Table A2 Classification4
Rock Loads an
Rock Load,
4)Initial
1.
Remarks
Final
Lining only is spalling
Hard and Intact
or
ErI
2.
Hard
bo
0.25B
50
popping
Spalling commnon
fied or
95
Schistose 1'
90
0'
r- 00
0.5B
3. Massive, moderately
H-
Side Pressure inclined,
if strata
some spalling
Jointed_________________
___
4. Moderately blocky'
20-
0.25B to
and seamy 6'
10
5.
4" 50 25
4)
0-35C
______________
0WP
0.35C
Very blocky, seamy and shattered
to
0.6C
to 1.1C
6. Completely
2"
7. Gravel
an
sand
0.514c
to 1. 0.914C
to
11
_ _ ______________ __
8. Squeezing,
.2C
moderate depth
9. 4) 0
Notes:
4)
side
If seepage, support.
pressure 0.3y (0.5Ht
13cSide l.08C to
Ph
1-38cI
Loose
1.1C
Heavy side pressure. Continuous support required.
Hp)
Us In circular support. extreme cases: yielding support.
4, 5, 6, 7, when above-ground water
loads by 50%. 2) For sands (7), Hpmin is for fo large width movements
3)
Considerable
Dense
up to 250'
Swelling
1) For rock classes
side
2.1C to
Squeezing, great depth
10.
0.62C to
to
r2.1C
Little or no pressure
pressure. continuous
1.1C
crushed
10
-_
is tunnel width, Fo circular tunnel,
density of medium,
small movements
(-0.15C). width Ht 2Ht. 2B
lbs/ft
A4
level, reduce
(-0.01C to 0.02C) Hpmax
height of tunnel
(in feet).
Table A3 Support Recommendations for Tunnels in Rock (20- to iO-ft Diameter) Based on
Alternative Suport Systems Rouk
.nneling ethod
R"
A.
90
Boring Machine
Steel Sets
Rockbelts
Shotcrete
None to occ. light set. Rock load
None to occasional
None to occ. local application
None to Occ. light set. Rock load (0.0-0.3)B.
NO-e
None to Occ. local application in. to
(0.-0.2)B.
B.
Conventional
to
occasional
3 in.
GOO". 75
RQD
90
A.
Boring Machine
Occ. light sets to pattern on 5-ft to 6-ft ctr. Rock load (0.0 to
None to occ. local application in. to
Occasional to pattern on 5-ft to 6-ft centers
3 in.
0.4)B.
B.
Conventional
Light
sets,
5-ft to
6-ft ctr. Rock load (0.3 to 0.6)B.
Occ. local appli-
Pattern, 5-ft to
6-ft centers
cation 2 in. to
in.
FAIR
50
RQ
75
A.
Boring Machine
B.
Conventional
to medium sets, i-ft to 5-ft ctr. Rock load
n. on
Pattern. 4-ft to 6-ft ctr.
.,.
Pattern 3-ft to 5-ft ctr.
in. or mere crown and sides
to
crown
(O.6-i.3)B.
POOR 25
Light to medium sets, 5-ft to 6-ft ctr. Rock load (O.4-1.0)B.
50
RQD
A.
B.
Boring Machine
Conventional
Medium circular sets on 3-ft to i-ft ctr. Rodk load (I.O-1.6)B.
Pattern, 3-ft to 5-ft ctr.
Medium to heavy sets on 2-ft to i-ft ctr. Rock load (1.3-2.0)B.
Pattern, 2-ft to
Medium to heavy circular sets on 2-ft ctr. Rock load (1.6 to 2.2)B.
Pattern, 2-ft to i-ft rtr.
Heavy circular sets on 2-ft ctr. Rock load (2.0 to
Pattern, 3-ft center,
I-ft
In.
in. on
crown and sides. Combine with bolts.
6 in. or more on
ctr.
crown and sides. Combine with bolts.
VERY POOR
25
A.
Boring Machine
(Excluding squeezong or swelling ground.)
B.
Conventional
in. or more on whole section. Combine with medium sets.
6 in.
more on whole section. Combine witt
2.0)B.
medium to heavy sets.
VERY
POOR'
(Squeezing
or swelling.)
A.
B.
Notes
I
Boring Machine
Conventional
Very heavy circular sets on 2-ft ctr. Rock load up to 250-ft.
Pattern, 2-ft 3-ft ctr.
Very heavy circular sets on 2-ft ctr. Rock load up to 250-ft.
Pattern. 2-ft to 3-ft ctr.
6 in. r more on whole section. Combine with heavy sets.
6 in.
more on whole section. Combine with heavy sets.
In good "d excellent quality rock, the support requirement will be, in general, minimal but will be dependent upor
Joint geometry, tunnel diameter, and relative orientations of jcints and tunnel. 2) Lagging requirements will usually be zero in excellent rock and w.1l range frum u to very poor rock. esh requirements u.su will be zerc in excellent rock and will range fr,.r casional 100$ mesh in very poor rock.
I,
to
tunnel width.
A5
g__
rock to 100$
i%
mesh (or straps) in good rock
APPENDIX B:
SUMMARY OF PROCEDURES
FOR ROCK MASS CLASSIFICATIONS
1. th
Th
procedures fo
convenience of
of geological
the engineering
fo
Th
collection
th
Classification-Rock Mass Rating (RMR) System
rock tunneling applications,
determined in th
utilizes
of rock masses, especially th
following si
b.
Rock quality designation (RQD).
c.
Spacing of discontinuities.
d.
Condition of discontinuities.
e.
Orientation of discontinuities.
f.
Groundwater conditions.
structural region an
is divided
tunnel route
above
si
number of
into
classification parameters
entered onto th
foliowing expianaLlons
of
field:
Uniaxial compressive strength of intact rock material.
rock mass along th
evolved
parameters, al
a.
regions, and th
Th
geologists responsible fo
This engineering classification
which ar
summarized here for
classifications ar
data.
Geomechanics
2.
rock mass
determined for each
ar
standard input data
and terminology ar
structural
sheet
(Figure B1).
relevant.
Structural regions
3. featires
These regions are geological zones of rock masses less uniform.
more or
ar
Although rock masses ar
nature,
they may nevertheless
type of
rock or the spacings of discontinuities
region.
In most cases,
in which certain
be uniform in regions wheLa,
the boundaries
ar
th
discontinuous example,
foL
in
the
same throughout th
of structural regions will coincide
with such major geological features as faults
and shear zones.
Discontinuities 4.
This
term means al
discontinuities
in the rock mass, which ma
be
technically joints, bedding planes, minor faults, or other surfaces of weakness.
It excludes major faults
regions of
their own.
that will be considered as structural
Intact rock strength
5.
Th
uniaxial compressive strength of rock material
accordance with th
standard lahoratory procedures, bu
B3
fo
is
th
determined in pur-ose
of
..
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:,
i
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OR
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.-
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rock classification, the
r~commended. rock core
retrieved from borings an
be determined in the field on
index ca
diameter.
points.
Th
I. such that fo
strength a,
24
close correlation exists
in
du
length.
incorporates
Shorter
index is based on
essential parameter
RQ
Fo
for core description,
determination,
th
ar
75-90
Good
50-75
Fair
25-50
Poor
it
orientation
the
sufficient parameter
Rock Mechanics
(core diameter of 2.16
in.).
Th
of discontinuities
spacing of discontinuities in the rock mass
planes.
Th
in th
is the
mean distance between th
direction perpendicular
strike of discontinuities
with reference to magnetic north. the
is no
Very poor
25
horizontal an
should be
follows:
as
Excellent
discontinuity
It
tightness, orien-
International Society fo
90-100
planes of weakness
rock mass.
to be
Core Quality
ROD, percent
Th
considered
rock mass.
of
accepted division of RQD values
8.
or greater
Consequently, while it is an
recommends double-tube, N-size core barrels
Spacing an
recovery proin
influence of discontinuity
gouge material.
full description
7.
ignored as they ar
lengths of core ar
tation, continuity, an
the
(2.16-in.
modified core
shearing, jointing, or weathering in th
to close
and the
only those pieces of core that ar
noted that the RQD disregards th
fo
standard NX core
(to
(ROD)
This quantitative
cedure, which
ratio of the
the
Is.
Rock quality designation
6.
fracture across
percent) between the uniaxial compressive strength
-2
diam),
result of
point-load strength index is calculated as
Th
is
piece of drill core
core fails as
applied load to the square of core diameter.
within
require any specimen
the core does not
Using simple portable equipment,
compressed between tw
index is
of the well-known, point-load strength
reason is that th
Th
preparation.
its
use
joint plane
is generally
to the
recorded
The dip angle is the angle between
taken in
B5
direction in which th
plane dips.
Condition of discontinuities
9.
parameter
This
their separation
includes
(distance
between
(persistence), weathering of th (gouge)
infilling Civil
Engineers
m~terial.
up
set
th
roughness
th
th
of
surfaces),
wall
rock of
following
their length
surfaces, continuity
or
and th
of weakness,
the planes
Task Committee
The
discontinuity
of
of the American Society
weathering
should be
classification which
used:
a.
No visible
Unweathered.
fresh;
b.
crystals
Slightly
Discontinuities
rock.
and may
contain
Discoloration may extend
to
surfaces
noted of weathering;
are
rock
bright.
weathered
discolored
signs
distance
thin filling
th
into
of
to
up
rock
or
stained
are
of altered material.
from
20 percent
discontinuity
the
of th
discontinuity
spacing.
C.
Moderately weathered
rock.
discontinuity planes
for
th
discontinuity
Slight distance
spacing.
of altered material.
discoloration extends greater
Discontinuities
Partial
20
than
from
of
percent
may contain
filling may be
opening of grain boundaries
observed.
d.
Highly weathered rock, and texture
th
is
that
should be
and in
of th
uniaxial
material with
10 material
is
personal
For
in
th
to or above
rock engineering,
rock and
soil
150 psi
th
is
quantitive
index that
completeness,
resistance
employed
in th
can now assess the
is
to
B6
defined
past before
th
on the
The
in terms
rock
to
th
strength
rock.
rock
reason
indentation
subjective
following hardness
the past:
is
information
not
has been
partly
considered as
th
parameter and
appearance
in terms of weathering.
as
defined
is
and
separated.
is
It
original separation of
external
texture
completely
which
strength
sake of
and not
The
that on rock hardness.
opinion.
point-load
boundary between
rock
to
is
The
totally discolored
preferable
strength
scratching,
in
is
condition.
have
the grains
strength equal
Furthermore,
rock
The
Internally, th
compressive strength
the
rock hardness,
th
rock. friable
of soil.
noted that
is partly friable.
occurred.
preserved, but
It
the
throughout
mainly been preserved, but
rock has
Completely weathered decomposed
Discoloration extends
rock material
the
grains has
the
e.
of
rock.
is
that
or geologist's
advent of
in
th
classification was
th
field. used
It
ca
be
a.
Very soft rock. Material crumbles under firm blow w__h sharp end of geological pick and can be peeled of with knife.
b.
Soft rock. Material ca be scraped an peeled with knife; indentations 1/16 to 1/8 in. show in the specimen with firm blows.
c.
Medium hard rock. Material cannot be scraped or peeled with knife; hand-held specimen ca be broken with th hammer en of geologica- pick with single firm blow.
d.
Hard rock. Hand-held specimen breaks with hammer en under more than on blow.
e.
Very hard rock. Specimen requires many blows with geological pick to break through intact material.
seen from the above
rock, hardness ca knife an
that for the
be assessed from visual
striking with
hammer.
to medium hard
lower ranges up
by scratching with
inspection an
However, fo
of pick
rock having th
uniaxial
compressive strength of more than 3,500 psi, hardness classification ceases to be meaningful test" th
du
difficulty of distinguishing by the
th
to
various degrees of hardness.
In an
indirectly related to rock strength, th
uniaxial
compressive
strength an
"scratchability
case, hardness
is only
relationship being between the
the product of hardness and density
expressed in the following formula: a,
lo
R + 316
0.00014
where dry unit weight, pc Schmidt hardness 11.
surfaces
Roughness or th
surfaces
Asperities ar
clean an
discontinuity surface.
This
high-angle asperities ar effectively increase ar
nature of
is an important parameter
discontinuities. if th
(L-hammer)
termed roughness.
"ride" over on
th
the asperities in th
characterizing th
discontinuity
condition of
that occur on discontinuity
surfaces
interlock,
closed, and inhibit shear movement along the restrain t on movement is of
sheared of
two types.
during shear displacement
peak shear strength of the
fracture.
Small
an Such
asperities
Large, low-angle asperiti es cannot be sheared of
another during shear displacement, changing
direction of shear displacement.
Such large asperities ar
B7
the
an
initial
termed waviness
an
reliably measured in core.
cannot be
Roughness asperities
12
measured in terms
usually have
of tenths of an
sized exposure of
inch an
discontinuity.
ar
stepped, undulating or planar):
b.
Rough. Some ridge and side-angle steps are evident; asperities ar clearly visible; an discontinuity surface feels very abrasive.
C.
Slightly rough. Asperities on th distinguishable and can be felt.
d.
Smooth.
e.
Slickensided.
strength of
distance between th
extent to which th
opposing surfaces
flow through th
discontinuity surfaces, ca
rock material contribute
discontinuity.
to
interlocked, an
both th
discontinuity is therefore dependent on th
nature
and th
separation of th
of th
filling material.
discontinuity
a.
Very tight:
b.
Tight:
C.
Moderately open:
d.
Open:
e.
Very wide:
that where
described as
th
absence
In th
th
Th
shear
asperities of
filling an
discontinuity shear strength.
th
separation, presence or absence of filling materials,
Note
interlock as well as
the separation decreases,
As
rock wall tend to become more
walls,
touch.
discontinuity filiing (gouge) controls entirely th
the discontinuity.
strength along
are
Visual evidence of polishing exists.
Separation, or th
interlocking, th
discontinuity surfaces
Surface appears smooth and feels so to th
amount of water that ca
th
core-
Very rough. Near vertical steps and ridges occur on th discontinuity surface.
controls th
of
readily apparent on
ar
a.
13.
th
amplitude
applicable descriptive terms ar
Th
defined below (state also if surfaces
base length an
The
the
shear
degree of
roughness of
th
surface
description of th
surfaces is given in millimetres as follows:
0.
mm
0.1-0.5 mm 0.5-2.5 mm.
2.5-10 mm.
10-25 mm
separation
is more
than 25 mm
major discontinuity.
B8
th
discontinuity should be
14.
Th
two-fold influence:
Th
infilling (gouge) ha
a.
Depending on the thickness, the filling prevents th fracture asperities. interlocking of th
b.
It
possesses its ow characteristic properties, i.e., shear strength, permeability, an deformational characteristics.
following aspects should be described:
type, thickness,
continuity,
an
consistency. Continuity of discontinuities
15.
rock material an rock mass.
In th
continuous
if its
quently.
discontinuities
th
extent to which the
separately affect th discontinuity
case of tunnels,
length is greater than th
continuity assessment,
fo
influences th
is considered fully
width of the
length of th
the
behavior of the
tunnel.
Conse-
discontinuity should be
determined. Groundwater conditions 16.
gallons
In th
case of tunnels,
per minute pe
general condition ca flowing.
1,000 ft of be
th
rate of inflow of groundwater
the
tunnel should be determined,
expressed in terms of the ratio of
available, these should be stated
water pressure
th
to
th
major
latter can be either measured or determined from the
Th
depth below surface, i.e., pe
or
described as completely dry, damp, wet, dripping, an
If actual water pressure data ar
principal stress.
in
th
vertical stress increases with depth at
1.1 psi
foot of the depth below surface.
Rock Structure Rating
17.
Th
Tiedemann, an a.
RS
b.
is based on the
Parameter A.
(2) (3)
ConceRt
Concept, developed in the United States in 1972 by Wickham,
Skinner,
(1)
RS
following three parameters:
General appraisal of rock structure is based on
Rock type origin. Rock hardness. Geological structure.
Parameter B.
Discontinuity pattern with respect to the direction of tunnel drive is based on (i)
Joint spacing.
B9
C.
(2)
Joint orientation
(3)
Direction of
Parameter C.
(1) (2) (3)
Although th the
inflow is based on
to parameters an Overall quality of rock du combined. Condition of joint surfaces. Amount of water inflow (in gallons per minute pe th tunnel).
However,
some confusion.
it
is
foot of
above parameters were not explicitly stated by
data needed ar
proposers, most of th
lead
tunnel drive.
Effect of groundwater
definitions of th
joint survey.
(strike and dip).
normally
recognized that th
An input data worksheet
included in
lack of
standard
definitions may
th
the RSR Concept
fo
is shown
in Figure B2
0-System fo
18.
Q-System, which wa
Th
Lien, and Lunde, 12 determines th (a)
of six parameters:
19.
rock mass quality
of alteration or
(e) water inflow or pressure, parameters ar
developed in Norway in 1974 by Barton,
RQD, (b) number of joint
(d)
weakest joints,
Tunnel Support
along th
first tw
parameters represent th
rock mass, and their quotient is claimed to be
quotient of th
Th
related to th
shear strength of
of water pressure, while
competent rock, an This
weakest These si
th
th
quotient of the "active stress."
crude measure of the relative
joints.
is said
to be
The fifth parameter is
sixth parameter is
(c) squeezing an
sixth parameter
overall structure of th
third and fourth parameters
load in the case of shear zones an
rock.
function
sets, (c) roughness of th
(f) rock stress condition.
an
as
grouped into three quotients.
Th
block size.
termed Q
(a) loosening
measure of:
clay-bearing rock, (b) rock stress swelling loads in plastic
is regarded
as
th
fifth and sixth parameters
is
An input data worksheet fo
Figure B3
BIO
"total stress"
in
incompetent
parameter.
regarded as describing th th
measure
Q-System is shown in
Th
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CLASSIFICATION INPUT DATA WORKSHEET
Q-SYSTEM Conducted by:
Project Name: Site
-f Survey:
late:
Structural Region:
Rock Type:
Sta. Sta. Sta. Sta.
JOINT SETS Massive rock, no or few Joints INo. of Joint sets present
Additional random Joints exist fractured
[Rock heavil
ROCK QUALITY DESIGNATION
Average RQ
Crushed rock
=%
Range =%
ry or minor inflow
ROUGHNESS OF JOINTS
.arge inflow, unfilled Joints rge inflow, filling washed out _Eceptional transient inflow ceptional continuous inflow
ough or irregular lckensided nie ndulating ot continuous
Approx. water pressure:
all rock contact wall contact
STRESS CONDITIONS stress, near surface 10-200 ed stress: c/ /a igh 'stress: cl 5-10
FILLING AN WALL ALTERATION ightly healed Joints
eakness zones with clay
Unaltered, staining only Slightly altered Silty or sandy coatings Clay coatings Sand or crushed rock filling >mm <5mm tiff clay of
CONDITIONS
WATER
mm
clay
huezingro qelling rock
tel tress
rock values if
determined:
>5mm
%orz.
vert.
>5mm
welling clay
GENERAL Uniaxial strength of rock material Tensile:
p
si psi
Compressive:
Strike and dip orientation of th Average
Di
strike
weakest
Joints
Average di
direction
Figure B3.
Input data worksheet
B12
for
th
Q-System
lb/sq in.
CASE HISTORY DATA: APPENDIX C: PARK RIVER TUNNEL
Table Cl
Description of Rock Typcs
Red Shale/Siltstone: The dominant rock type is reddish-brown shale/ siltstone. The shale contains sandy phases and is interbedded with gray shales an thin sandstones. It is thin bedded and calcareous.
open-bedding planes, Th Calcite fills shales ar usually well cemented an moderately hard, bu some zones classified as soft an weak. Th sandy phases ar mostly competent ar and hard to very hard. Shale samples from near the intake exhibited slaking-like action when submerged. This is attributed to stress re Bedding strikes roughly north-south an generally dips lief by coring. 10 to 20 deg to th east bu with local variations. Gray-Black Shales: re with th shales.
Gray and sometimes black shales are interbedded They ar thin-bedded an Th similarly oriented.
beds ar thinner than th red beds an were used as markers to correGray shales ar late between boreholes. calcareous, moderately hard to similar in physical properties to the red shales. ar soft an
Thin whitish to gray calcareous sandstone beds are comSandstones: Many sandy zones appear to correlate between mon within th shales. boreholes and were used as markers. The beds are hard but sometimes show some solution activity an localized concentrated jointing. Variations include coarse red sandstone (arkose) and thin zone of interbedded volcanic sandstone an shale that were encountered in only boreholes, but in no other borings. tw Basalts: Basalt flows near the intake shaft ar oriented consistent with the local stratigraphy although structural modifications ar
apparent. They are usually gray and olive gray (locally black), slightly vesicular and nonvesicular, calcareous, hard, and contain headed hairline fractures throughout. Localized broken an weathered zones occur. Aphanite: This gray fine-grained to glassy rock type occurs in borehole FD-9T between the depths 137 and 18 feet. It origin is uncertain an it occurs in zone with unresolved structural discontinuities. It is hard to very hard but also contains numerous irregular healed hairline fractures. Some zones may be slightly weathered an less dense.
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BORING NO. BORE HOLE PHOTO LOG (A
example)
FD-B-T
NAME
LOCATION
Park River Tunnel
Hartford, Connecticut
DATE PHOTOGRAPHED
IRIS SETTING
Nov 27-38, 1975
5.
DEPTH PHOTOGRAPHED
WATER
35.0 to
Flowing at
220.0'
FFET CASING
(In
Photo)
35.0-39.0' DEPTH
CONDITION OF
Good
and 4.
WATER
DEPTH Surface
CONDITION
Clear
FEET CONCRETE (In Photo)
FEET ROCK
None
39.0-220.0'
RANGE
45.5-46.2
BORING
(In Photo)
DESCRIPTION
45 °E
Jt.,
Str.
with
wnhte material
dip
80 ONW,
1/8" at
top to
1/32" at bottom, healed
(smooth), planar, terminates at bedding Jt
at
bottom 45.2-46.3
46.2 46.3-160.O
Gray-green rock Bedding Jt., Dark gray
At
53.6
51
Jt.
Str. N-S,
dip 15
OE, 1/16" partly open, rough, planar
rock containing numerous small irregular white inclusions
feet rock gradually changes to dark blue-gray color
Str.
70
OE, dip 20
SE, 1/32-1/16" partly open,
stained,
rough,
planar 53.9-54.1
Jt.,
Str.
W, dip
20
30 ONE, 1/32-1/16" partly open, stained,
rough, planar 54.3-54.7
Jt.,
56.2-56.3
Jt.,
30 °W
Str.
material,
dip
50 ONE, hairline-i/32", healed with white
rough and irregular
Str. about N-S,
dip 45
'W, 1/32", healed with white material,
rough, irregular, discontinuous
56.7-57.9
Jt.,
58.4-59.3
Jt.,
30 °E
Str.
material,
rough,
dip
10 °E,
Str.
80 °NW, hairline-i/32", healed with white
planar, discontinuous dip
75 °W, 1/32-1/16" healed with white material,
rough, planar
59.1
Jt.,
Str.
N-S, dip 10 °E
1/16" healed with white material, rough,
irregular
59.0-59.5
Jt.,
Str.
10 °E
rough, planar,
60.7-61.5
Jts.,
Str.
dip 75
oW, 1/16" healed with white material,
discontinuous
10 °E
dip 75 Ow, 1/32-1/16" healed with white
material
Figure Cl.
Typical drill log
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CLASSIFICATION INPUT DATA WORKSHEFT
Q-SYSTEK
Site of Survey:
Hartford,
Structural Region: Sta. Sta. Sta. Sta.
Date:
Conn.
Subregion
G. A. Nicholson
Conducted by
Park River Tunnel
Project Name:
Hock Type:
l(a)
Shale
98+10-95+20
JOINT SETS Massive rock, no
or fe joints sets present Additional random joints exist Rock heavily fractured
No
ROCK QUALITY
DESIGNATION
of joint
(es
Crushed rock
Average RQ
20-90
Range
WATER
ROUGHNESS OF JOINTS ough or irregular mooth lickensided Undulatni lanar
3ry or minor inflow
edium inflow large inflow, unfilled Aoints ,arge inflow, filling washed ou xceptional transient inflow .xceptional continuous inflow [Approx. water pressure: 40 lb/sq
iuos
Nall rock contact wall contact
FILLING AN
in.
STRESC CONDITIONS Low stress, near surface 10-200 4ed. stress: a/01
WALL ALTERATION
Tightly healed joints Unaltered, staining only altered Slightly _________________________ Silty or sandy coatings Clay coatings Sand or crushed rock
tiff clay Voft clay Swelling clay
CONDITIONS
<5mm
ig
7-1
/a,
stress:
leakness zones with
hear zones
5-10
clay
eezinro
Squeezing rock Swelling rock
filling >5
Stress values if determined: 450 132 ps %orz. vert. N/
>m
>5mm
GENERAL
Uniaxial strength of rock material Tensile:
si
N/A
si
Compressive:_80p Strike and dip orientation
th
weakest
Average di
Average strike
Di
of
to NF
direction
Joints
!0 Se No. lariest
has joint
openings.
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CLASSIFICATION INPUT DATA WORKSHEET Q-SYSTEM
Project Name: Site
of
Sta.
Sta. Sta. Sta.
Hartford.
Survey:
StructL
Conducted by:
Park River Tunnel
Date:
Conn.
egion:Subregion
G. A. Nichnlhrnn shale and/or shale an interbeds
Rock Type:sandstone
1(b)
91+70-90+25
89+85-88+30
JOINT SETS
82+50-57+10
Massive rock, no
56+60-31+10
No
_20-100
ry or minor inflow
inflow inflow, unfilled joints ou inflow, filline washed ou rg ceptional transient inflow
edium
irregular rrge nsieg
nduating
xceptional continuous
lanar ot continuos rock contact al No wall contact
inflow lb/sq
Approx. water pressure:
Low stress,
near
4ed. stress:
igh
joints
stress:
surface
a/ac
10-200
ac /a
5-10
---c
Unaltered, staining only
eakness zones with clay queezing rock
Slightly altered Silty or sandy coatings Clay coatings Sand or crushed rock filling >5mmt <5mm Stiff clay >50 mm Soft cl mmvert. Swelling clay
weln
<5mm
Swelling rock Stress values
if determined:
N/A
132 ps 1rz.
>5m
GENERAL Uniaxial strength of rock material N/A
Tensile: Compressive: Strike and di
psi psi (avg)
8900
orientation of the weakest joints
Average strike Di
in.
STRESS CONDITIONS
WALL ALTERATION
Tightly healed
ve
CONDITIONS
WATER
ough or
FILLING AN
12
Crushed rock
80
ROUGHNESS OF JOINTS
mooth
joints
of Joint sets present Additional random joints exist Rock heavily fractured
ROCK QUALITY DESIGNATION Average RQD Range
or fe
direction
Figure
N10E
22
Average di
SE
C3
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CLASSIFICATION INPUT DATA WORKSHEET
Q-SYSTEM Project Name: Park River Tunnel
Conducted by:
Site of Survey: Hartford, Conn.
Date:
Structural Region:
Rock Type:
Subregion l(c)
23+10-7+10+
Sta.
JOINT SETS
Sta.
Massive rock, no or few Joints
Sta. Sta._
Average RQD Range
Additional random Joints exist Rock heavily fractured Crushed rock
72
30-100
WATER CONDITIONS Dry or minor inflow
ROUGHNESS OF JOINTS
edium inflow rge inflow, unfilled rge inflow, filling washed out cePtional transient inflow
Rough or irregular mooth
lickensided
nidulting
Eceptional continuous
Planar
rock contact al No wall contact
STRESS CONDITIONS ow stress, near surface
FILLING AND WALL ALTERATION
/0, 5-10 with clay eakness zones c1 hear zones 3Quezing rock
figh stress:
naterdstani~ony staining on). Unaltered, altered Slightly Silty or sandy coatings Clay coatings Sand or crushed rock filling >m <5 clay tiffifcly >5mml <5mm
Swelling rock Stress values
clay
=10-200
stress:
led.
Tightly healed Joints
=welling
inflow
pprox. water pressure:
continuous
oft clay
sets present
of Joint
__No.
ROCK QUALITY DESIGNATION
lo
G. A. Nicholson
USO+
vert.
>5mm
13
if determined:
ps
%orz.
N/A
GENERAL Uniaxial strength of rock material Tensile:
N/A
psi
Compressive:40-8000 Strike and dip orientation Average strike
N23E
Dip direction
SE
Figure
C4
psi
(assumed)
of the weakest Joints
Average dip
(Sheet
C1
of 3)
20
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CLASSIFICATION
INPUT DATA WORKSHEET
Q-SYSTEM Project Name:
Park River Tunnel
Conducted by:
Conn.
Date:
Hartford,
Site of Survey:
Rock Type: Basalt
Structural Region:
%-
Sta.
-91-70
JOINT SETS
88+30-82+50
Sta. Sta. Sta.
Massive rock, no or few Joints No
ROCK QUALITY
WATER CONDITIONS
ROUGHNESS OF JOINTS ough or
or minor inflow
Dr
edium
irregular large
inflow
inflow, unfilled joints Large inflow, filling washed ou Eceptional transient inflow xceptional continuous inflow
mooth lickensided ndulatin
lanar lot continuous
5n lb/sg in
water pressure:
-pprox.
rock contact
STRESS CONDITIONS
No wall contact
ow stress,
FILLING AND WALL ALTERATION Tightly healed Joints
near surface
4ed.
stress:
igh
stress:
a/a
c!
c/a
10-200 5-10
Unaltered, staining only zones ean Shear zones Sweeling rock rock Swellin
Slightly altered
Silty or sandy coatings Clay coatings Sand or crushed rock fillin tiff clay >mm+
mm <5mm welling cl
tress
values if determined:
'vert. 13
%orz.
ps
N/A
GENERAL
strength of rock material
Uniaxial
N/
Tensile:
psi
Compressive:10,000+
Strike
an
di
direction
ps
orientation of th
N1OE
Average strike
Di
Lies
Crushed rock
90
60-100
Range
joint sets present
of
Additional random joints exist Rock heavily fractured
DESIGNATION
Average RQD
all
G. A. Nicholson
weakest joints
Average di
_A
Figure
C5
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of
3)
65
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CLASSIFICATION INPUT DATA WORKSHEET
Q-SYSTD4 Project Name:
Park River Tunnel
Site of Survey: Hartford. Conn.
Date:
Structural Region: Sta. Sta.
95+20-94+70 90+25-89+85
Sta.
57+10-56+60
Rock Type:Basalt
and/or
Crushed rock
17-28% 1-35%
WATER CONDITIONS
ROUGHNESS OF JOINTS
ry or minor inflow edium
irregular
Smooth
Exceptional continuous inflow 55lb/sq in. Approx. water pressure:.
otnar continuous
all
inflow
inflow, unfilled Joints rg Lrge inflow, filling washed out xceptional transient inflow rsur: bs
'ickese
plickensided ndulatin
lo
rock contact
No wall contact
STRESS CONDITIONS stress, near surface
FILLING AN
Owelling clay
High stress:
/o,
hezne
10-200 5-10
l1
zones with cay rone
SQueezing rock welling rock Stress values if determined:
>m
<5mm <5mm
o/c.
eakness
Silty or sandy coatings Clay or crushed rock filling Sand coatins
tfand or cruse rk tiff clay
stress:
ed
WALL ALTERATION
Tightly healed Joints Unaltered, staining only Slightly altered
Poft clay
Joints
sets present
Additional random Joints exist Rock heavily fractured
DESIGNATION
Average RQD Range
and
>5mm >5"m
Overt.
%orz.
GENERAL Uniaxial strength of rock material
NI
Tensile: Compressive: Strike an
di
Average strike Di
direction
si
8.4-10K
psi
orientation of the weakest Joints Average di
N/
N/A
Figure C6
(Sheet
C20
of 3)
NIA
sh
ss/sh interbeds
JOINT SETS or fe
No. of joint
ough or
interfane
Massive rock, no
Sta. ROCK QUALITY
G, A. Nirhn1,n
Conducted by:
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CLASSIFICATION INPUT DATA WOPKSHEET Q-SYSTEM4
Project
Date:
Site of Survey: Hartford, Conn.
Rock Type:Shale with stone
Region:
Structural
31+10-23+10
Sta. Sta. Sta. Sta.
G. A. Nicholson
Conducted by:
Park River Tunnel
Name:
JOINT
interbedded sand-
SETS
Massive rock, no or few joints No of joint sets present Additional random joints exist
ROCK QUALITY Average
Rock heavily fractured
DESIGNATION
RQD
Crushed
__0%
rock
20-100%
Range
WATER CONDITIONS ry or minor inflow
ROUGHNESS OF JOINTS
i-flow dium ed i'fw inflow, rr
irregular rgar
or ough oh
_____________________
xceptional continuous inflow pprox. water pressure:
rock contact al No wall contact
STRESS CONDITIONS
ow
WALL ALTERATION
4ed.
Tightly healed Joints Unaltered, staining only Slightly altered coatings Silty
or
stress,
stress:
near
a/
stress:
ig
Clay coatings
Sand or crushed rock filling
welling rock Stress values if
laN Swelling clay
5-10
with clay
Squeezing rock
______1_1_____
surface 10-200
oc/o
eakness zones zones 3hear
sandy
_______clay
,oints
inflow, filling washed ou xceptional transient inflow
lickensided 'ndulating Ianar Notcontinuous
FILLING AN
unfilled
determined:
a450 voft Overt" N/Aorz.
>m
>Smm
132 psi
GENERAL
Uniaxial Tensile:
strength of rock material N/A
ps
Compressive: 8300
Strike an
di
Average strike Di
direction
psi
orientation of th
N2qF
weakest Joints
Average di
15
SE
Figure C7
(Sheet
C2
of 3)
lb/sq in.
APPENDIX D:
RECENT DEVELOPMENTS
IN THE USE OF ROCK MASS CLASSIFICATIONS FOR TUNNEL DESIGN
(1979-1984)
"Imagination is more important than knowledge." Albert Einstein
Introduction
1.
last five years, rock mass
In th
valuable tool fo
themselves as
quality of rock masses
engineers and geologists fo
engineering
fo
classifications have established
purposes, *.
assessing
They have received
increasing attention in the field of civil engineering as well as an
th
in
have been applied in many countries to different engineering
problems
In addition to providing guidelines fo
',
requirements
in tunnels
extended to estimate
rock support
and mines, rock mass classifications have been
rock mass deformability
as well as
th
strength of rock
maL,;es. ,7
2.
significant recognition of th
is found in
Europe, where tunnel construction contracts
classification as
rock mass
contract documents.
Rock Mechanics
Geology
Exploration an
On the
payment
in accordance with
international scene,
(ISRM) and th
(IAEG) have
the United States,
basis fo
commission on rock classification.
Committee D-18 ha
In
Transportation Research Board (TRB) Committee on
application, evaluation, an an
study rock
International Association of Engineering
each established th
standard
International Society
the
Classification of Earth Materials ha
classifications
in Austria incorporate
Moreover, special committees were appointed to
mass classifications. fo
importance of rock classifications
correlation
responsibility of
of existing earth-materials
American Society fo
th
th
Testing an
been charged with developing
Materials
(ASTM)
set of rock-classification
standards.
3. rock mass
tunnels
Th
purpose of
this appendix is
to update
the state of th
on
cl-ssification systems as used for the design and construction of
in
rock.
This
appendix is accompanied by an up-to-date list of
ref3rences.
Se
ar
appropriate footnote reference number at en
D3
of Appendix D.
4.
classifications systems have emerged as dominant
rock mass
Tw
recent years, namely th
applying them to various
much of the
areas of rock engineering
devoted to updating th
present review will be
developments concerning
these
classification systems. 5.
logical approach to discussing th
(2) rock support requirements,
developments
(3) influence of stress
Provision of
each of th
geological report ha
data is arranged in
in Appendix
This is so because even if
been prepared fo
classification systems will be
successful us
crucial to th
three classification systems
particularly useful.
report ar
(4) rock mass
of
Special input data sheets such as those
classification system.
presented fo
field,
Input Data
Reliable input data continue to be
rock mass
(1) input data,
(6) emerging new applications.
deformability, (5) strength of rock masses, an
6.
concerning rock
following headings:
classifications is to consider th
mass
an
th
Many papers have been written comparing these classifications an
Q-System.
tw
Classification (RMR System) an
Geomechanics
in
comprehensive
construction site, us
greatly facilitated if th
of this
of th
geological
input
given rock
convenient form compatible with
classification system. 7.
In this connection, special reference should also be made to US Army
Corps of Engineers document ETL 1110-283 dated guidance on th depicts th
31 Ma
use of rock mass classifications fo
recommended input data sheets fo
us
1983 which gives
tunnel
with th
support an rock mass
classification systems. 8.
trend has emerged to collect engineering
rock mass classification purposes th
need fo
availability an
investigations
on
the basis
in adits or pilot tunnels.
of more advanced coring
rock mass classifications
ca
As
result of the
techniques such as directional
D4
drilling
and core logging proce-
be performed on th
data from boreholes.
for
of borehole data alone without
oriented core sampling as well as both borehole
dures
geological parameters
basis of th
input
9.
Figure Dl shows the results
comparison of the RMR values
featuring
Budavari
in situ mapping.
and from
recent study by Cameron-Clarke an
of
underestimate somewhat the the Q-System there wa
It wa
obtained from borehole core
concluded that borehole data tend to In fact, using th
in situ values.
an 82 percent
probability of
RMR system or
borehole classification
rock mass being correct.
of
10.
In
recent paper, De Vallejo
characterization based on th
RM
determining rock mass rating values
fo
based on geological explorations from th establish
applicability of
presented an approach to tunnel site
surface.
surface data to tunnel depths.
parameters have been introduced an
some RM
This research aimed to
underground excavations in Spain.
applied
The approach wa
preliminary investigations and some findings ar
Modifications to
to civil
and mining
recommended fo
depicted in Figure D2.
Support Guidelines
11.
rock mass an
the
Recommendations
fo
support measures to be used in connection with
classification systems have no
support charts given useful ne
12.
guidelines by Hoekl
in this
changed during th
report are still applicable.
development wa
presentation of simplified design
giving approximate relationship between excavation
stability, maximum compressive boundary stress, an of RM
an 13.
Q-values. Ne
This
al.
Th
rock mass quality
in terms
is depicted in Figure D3.
comprehensive
support guidelines have been prepared fo
metal mining featuring modified RMR values from th
fication.
past five years
Geomechanics
us
in
Classi-
interested reader is referred to a publication by Kendorski et
(1983).
D5
to0 s-RMR(BC)-RMR(INS)±
19
80 so
X7
6: 30
2~0
4'+
30 20
20
30
0~
40
50607
SOS/ Del
O8e00
Out
-~
COSRMR seeS
Figure D2.
lassificationeck mass reockmecanis aundnfro from b n o e e r e urin xlratingobane
Cofparins sufc
of
ionstucmaing aftrS) a f t e a m r o
BudavariD8
lakn
TUNNELING QUALITY INDEX 0.01
0.001
0.1
40
10
1.0
1000
400
I00
STRUCTURALLY 0.1
0.1
CONTROLLED
FAILURE
-~
F9R
GENERALLY LIGHT
04
.3 .-
UPPORT MEDIUM SUPPORT
0.40.5NARHEA
ow .6
00
0. -0.6
TO MAINTAIN
STABLE OPENINGS
i°. DZ
0.4
SUPPORT
NOT
--
.7
U4<
-0.3
0.7
4X to.
0.6
0.9 LI
STRESS INDUCED FAILURE
POOR
gVERY
30
20
10
40
s0
60
FAIR
IPOOR
100
90
0.9 LO
VERY 0000
0000
ROCK MASS RATINGS Figure D3.
60
70
0.8
RM
Approximate relationship between excavation stability maximum compressive boundary stress rock mass quality an ( a f t e r Hoekl°).
Influence of Stress Field
14.
considerable
classifications for use
mass
conditions.
This
research was
directed to
research
is
excavations
at
greater depths
is particularly applicable
relevant
as
of research has been
amount
well
applications
to tunneling as
simplified chart
the Geomechanics
rock mass which and
support
or
recommendations
such as
may be
is
depicted
the mine
in Figure D4.
to
for production drifts
D7
encountered
arrive
to
appropriate more detailed
on RMR values has been
operator
This
loads.
featuring additional adjustments
Classification,
the planner
mines
this
of adjacent
influence
conditions
classification procedure based
enables
and in changing stress
involving block caving
in civil engineering involving varying applied
15
adapting rock
in deep level mining an
featuring the
changing stress
devoted to
developed"
at rock mass quality
in block
caving mines.
The
Strength of intact rock
Blasting damage adjustment
Rating: 0-15
0.8-1.0
Discontinuity
density 0-20 RQD: Spacing: 0-20
In-situ stress
Discontinuity orientation adjustment
change of stress adjustment
A, 0.6-1.2
Rating: 0-40
"-'-"0-100 Basic RMR, Major faults Discontinuity condition
fractures
Rating: 0-30
0.7-1.0
Adjusted RM
Groundwater
RMRXAaXAsXS
condition
max. 0.5
Rating: 0-15
Support recommendations
Figure D4
Adjustments to the Geomechanics Classification
D8
procedure involves adjusting RMR values
mating support requirements
mining purposes and then esti-
fo
an
development
fo
production drifts.
dure ic diagrammatically depicted in Figure D5.
Modified Basic RM
This
system,
The proce-
knorn as
the
system or MBR in short, is based on experience gained in an
in-depth field study at several block caving mines
in th
United States.
Strength of Rock Masses
Rock mass classifications
16.
in situ strength of rock masses.
failure criterion fo of rock materials.
recently became useful fo
Hoek an
1/2 a.
a, is th
major principal
stress at failure
a3
minor principal
stress
is th
th
an
uniaxial compressive strength of rock ar
th
constants which depend upon th
rock and th
extent to which
by being subjected
to a,
above equation to triaxial fo
rock material.
fo
s -
an
between
an
an an
Brown
Hoek-Brown criterion
that th
original relationships
the fact
that laboratory
and Priest and Brown 14 recommended
the value of Bieniawski's
RM
an
were based on
RMR.
These
small number of
Brown and Hoek 15 have since determined
data points and were not well defined.
Thus, th
fit of the
Figure D6
original relations between
disturbed.
c3.
test data from laboratory specimens, taking s -
For rock masses, Hoek an
relationships
of
been fractured
Using sandstone as an example, th
is depicted in
18
it ha
properties
which is determined from
For intact rock,
17.
strength
Their criterion is as follows:
Or
is
proposed an empirical
the strength of rock masses as opposed to th
a:
where
Brown
estimating the
gave lo
values of rock mass strength du
test specimens from which
tb
were derived were
original relationships were considered suitable fo
D9
to
use
-ff ag ZW
gt a. ol
V)
LT
cr a. .7
Q:iu
wa: 41
CC
CL
crMu (L
40
awa
cc -9
cn
0 1.-C am
CC moz (L
U.
-H ca bo-A -14
$,-1.
cz 41
LU CC
r-
-,4
t3v) 5:
cz
r-H
ci
4-1 CZ
ca
C) Q) -H J-j 1-4
0.
U)
0.10
wz =2
0-:
a zo
4-4
0.
WZO
0.2
MW
ul
am
4J r_;
4-1
cu
4,
Wq
im
max
0
00 4 W W CC
Ow
Z1 1..- ca
(n
co gn
09
CL
Ulm< 49
44
I=
IL %J
-Ja
0)
4-4
WI 0z43 =W wee
t;
0.40
----
a)
1-i
20
wu) auw
$4
cz
00> utew
c.
(1)
1.4 (1)
mu.0 -j mmw
LL'ir
'4 U)
co
a: U)
ci
WI-0
4m 04
G:Cxm
--24
4c at 0 tj U
CD
00
ca
1: co -A LW
4-j
Ln
CL
cc
ou
X0 Iz in f..
cr
ZO 13 uj
Xj IL
.0
Z2 i:
t:
ra
Zo Oz UO
ME
D10
to
ca
jC
LA
06
4-
f1-0.5 Effectilve normal
-Uniaxial
-.
compressive
0I2 Minor principal
Uniaxial
stress
_
_
strength _
ac
_
stress 03
compressive strength
Results of triaxial tests on sandstone for Figure D6. Hoek-Brown in th determining parameter criterion (after Hoek and Brown'1
Dll
in estimating
peak strengths of disturbed rock masses
th
such as
these on th
boundaries of slopes and underground excavations that have been loosened by those in embankments or waste
Door blasting practice an Hoek 15 suggest
M_
following expressions:
RR1-00
ex
(RMRl00)
=exp
When mechanical excavation,
19.
essentially undisturbed. developed in
perimeter blasting techniques, or,
good blasting practice ar
some cases, normal
used, th
these cases suggests
estimated by th
an
that th
RMR 100)
Brown
ha
both disturbed an an
mass while
rock masses ma
28
=exp
upper
values
following expressions:
Mi
Hoek an
be left
(iMR-100\
ex
m__
in
rock mass strengths
Back-calculation of th
number of
rock mass ma
corresponding to peak strengths of undisturbed or interlocked be
Brown an
recommendations
slight modification to Priest and Brown's
disturbed rock mass, suggested the
and, fo
dumps.
compiled
values
an
undisturbed rock masses as reproduced in Table Dl.
for
Th
each rock mass category refers to disturbed rock
values fo
th
list of approximwIe
lower refers to undisturbed rock mass.
Shear Strength of Discontinuities 20.
Serafim and Pereira 17 utilized th
Geomechanics
estimate from RMR values both the
shear strength of
shear strength of discontinuities
in rock.
of the
an
friction of th in th
as
the
they used the
dr
"condition of disconti-
"groundwater" term to estimate
discontinuities
in rock masses.
on
an
Th
value of 45
state were given
effective reduction of 100.
this purpose,
intact rock and utilized th
nuities" together with th
joints
rock material an
point load strength and/or uniaxial compressive strength to
ratings fo
estimate
Fo
Classification to
th
angle of
roughest, unweathered Flowing water
caused an
gouge-filled discontinuities had values of
In general, this approach wa
useful addition to the RMR-System.
D1
considered as realistic by Barton an
Estimates of
21.
nuities, an
the shear strength of rock material an
as presented by Serafim and Pereira17
ar
of disconti-
reproduced in Tables D2
D3. 22.
An alternative approach wa Q-System wa
that after th
arctangent of
(Jr/Ja)
also provided by Barton
developed, it wa
wh
mentioned
discovered by chance that the
surprisingly realistic estimate of the
gave
shear
strength, namely:
friction angle
It wa
suggested
that on
tan-
(J./Ja)
can base the
case of unfilled rough joints bu
design on peak shear strength in the
only on residual strength
in the
case of
clay-filled discontinuities.
Deformability of Rock Masses
23.
Ne
research ha
been conducted into estimating rock mass deforma-
bility by means of rock mass classifications. correlation between th from the Geomechanics
modulus of deformation an
Classification.
provided correlations between RM The complete correlation
also proposed
ne
an
th
50.
rating RM
Recently, Serafim an
Pereira
poorer quality rock masses having RM in Figure D7.
is
Serafim and Pereira
correlation as follows:
10 40
This equation is plotted
in Figure D8 together with th
collected by Serafim an
Pereira 17
recent paper, Barton
In
of deformation values
an
Q-values.
He
experimental
data
compared methods of estimating modulus
from rock mass classifications.
deformation modulus as well as th terms of RM
rock mass
RMR-100
E.
24.
featured
data presented included better
Th
quality rock masses, namely, having RM
50.
Previous work
Th
mean values of
range of modulus values were analyzed in
suggested the
estimating mean deformation moduli:
D13
following approximation for
90
%a.
8D
60 4- I T O I S
250
IIINASG17
C1/+
10
o0
Fiur 20.
60
hHISTumouuoeorS:
Correatio
1ER1
-10
1
20
40
Fiur 7.1 C o r l t o
ewe
10
950-HAIC
h
198 +0
RR
MASRTN
ROC
CASEee
1
eomto
nstumdlso
01
:-~ D~
04 SER/
09PRER,18
0-
+A -+ w~0
_j
10 00
CASE HISTORIES:
8IENIAWSKI, 1978 SERAFIM PEREIRA, 1983
-+
10
Figure D8.
20
30
50
40
60
70
GEOMECKANICS ROCK MASS RATING (RMRj
Representation by Serafirn an RM between Em an
D1
Pereira
s0
of the
90
100
relationship
25
Eean
lo
An upper-bound an Em
10
lo
Emax
40
lo
lower-bound to the measured data were
given by
Estimating Tunnel Convergence from Rock Mass Rating
Moreno-Tallon
25.
provided interesting information on the
bctween convergence deformations an case history in Spain.
on shows
the
rock mass rating
function of
as
time an
with support and depth being considered constant. shown to exist between rock-bolt behavior
suggested that development of
support an
state of stress.
tunnels,
based
This concept is illustrated in Figure D9 which
tunnel deformations
attempted, incorporating th
MR fo
relationship
rock mass rating RMR,
relationship wa
MR values.
nd
also
been
It ha
"general convergence equation" should be four main variables: This represents
rock mass rating RMR,
time,
ew field of application for
rock mass classifications. In an independent
26.
cable of
for estimating
th
study, Unal 19 showed th
span, support pressure,
system to be appli-
actual convergence of coal mine tunnels as
In essence, he proposed an
time.
RM
time, an
function
integrated approach to roof with roof
deformation.
This
is diagrammatically
presented in Figure DIO.
General Remarks
On
27.
selection of graphs"l
th
D1I.
useful developments in the past five years wa
ratings
giving the
in Figure if
of th
for
the various classification parameters
relationship between this parameter an
It
from
its value as shown
Problems previously arose as to what rating should be selected
given parameter value was on th 28.
the
also became apparent
borderline between tw
that while
ranges of data.
the parameter RQ
an
th
parameter discontinuity spacing were justified to appear separately in classification system, there existed
correlation between th
D1
two.
number
50
40-
RMR
g70
-2
T, ays 040
__50
__60_
70
DEPTH
AND%0
SUPPORT
CONSTANT
Figure D9. Diagrammatical representation of tunnel convergence observations with RMR and time (after Moreno Tallon
D16
11
10
-0
o0
cc
-Ile
-d
ID
44
4. Ni
6NVdS
)
-Y
no
In
In
NOt1Vkftd.OaCI
JOOU
1A
-0
00
D17
U1
4J
14
~-
13
10 ..
...
RANGE OF POSSIBLE ROCK STRENGTHS FOR SELCTED
*
INTCTROCKATRNGTH
IS
202
10-
08 00
4-4
22
'40 80
100
0--q
RQO,
Figure Dll.
DISCONTINUITY SPACING
Ratings for intact rock strength and discontinuity density. The stippled area allows latitude in assigning ratings where biased test results from point-load testing are suspected (after Kendorski et al.
D18
of studies were conducted, notably by Priest and Hudson20
tionship between RQD and discontinuity spacing wa
development, with th
ratings were allocated fo
Geomechanics
RQ
derived.
discontinuity spacing fo
an
estimate is needed of the
parameters is no
tw
corresponding parameter.
core is not available from boreholes ye
surface drilling and can be
an
available an
situations when
discontinuity spacing
used to estimate
use
This figure is
There ar
other hand, RQD values ma
On th
rela-
Based on this
Classification as shown in Figure D12.
particularly useful when one of the
from tunnel mapping.
in which
is available
be available from
discontinuity
spacing at tunnel
depth. Finally, it became
20.
apparent that no matter which classification
system is used, the very process of rock mass classification enables the
designer to gain
better understanding of th
geologic parameters
better
in
various
influence of th
the overall rock mass behavior and, hence, gain
appreciation of all the factors involved in the engineering problem.
This leads to better engineering judgment.
matter
is best;
is better
it
study, obtain
popular
better
"feel"
or more systems
tw
fo
the
th
Q-System.
tunneling projects fo
really
These tw
parametric
and, through
rock mass.
rock mass classification systems ar
Classification) an used on
to tr
it does no
agreement on which rock classification system
there is no general
that
Consequently,
It ha
emerged
the RMR System
systems
that the most
(Geomechanics minimum, be
should, as
comparison purposes.
Conclusions
30.
There were substantial developments
fication systems in the past five years. the usefulness
classifications ca
It
is obvious
only be derived
value of
It
benefits that ca
if more case histories ar
systems as well as th
is recommended
systematically used on
pointed ou be
that further benefit from rock mass
the classification
terms of engineering design.
systems ar
These developments have
of rock mass classifications and th
derived by their use.
assessing th
concerning rock mass classi-
benefits
that rock classification
tunneling projects,
D19
available for
that at least
two
in
ow 00
0___.__H
-E
NmE
U) 24
00 C:
0~V
4~
systems ar is kept of
always
selected fo
their application during the
Rock mass classifications
31.
in design but not as
an ai
comparative purposes and that careful record
construction of
should always be applied judiciously as
replacement
value is in quantifying engineering
fo
engineering design.
geological descriptions
estimating support requirements in the planning stage. cations ar
also useful fo
Th
emerging applications include development
between tunnel convergence 32.
measure of th
an
th
Fifth International
Australia.
friction of rock of relationships
class.
organized in 1983 at
International Symposium on
Underground Construction held in Lisbon, Portugal, an Congress on Rock Mechanics held in Melbourne,
Eleven papers on th
Symposium while
Rock mass classifi-
interest in rock mass classification is the fact
major international conferences, namely, th
Engineering Geology an
of rock masses an
time as functions of rock mass
that special sessions on rock mass classifications were tw
The main
estimating the in situ strength of rock masses,
modulus of rock mass deformation as well as cohesion an masses.
tunnel.
subject were presented at
15 papers were delivered
D2
Lisbon
at the Melbourne Congress.
other recent papers on rock mass classifications references.
th
ar
These an
given in the list of
REFERENCES
1.
Celada, B.,
Abad, J.,
Classification to
Application of Geomechanics Gallaeries
Coal Mine
2.
1980,
Barton, N.
4.
Z. T.
Vol.
15
1978,
to
Shear
International
September
1983,
Vol. II
The Geomechanics
Rock mass
for
standardization.
DC,
1981, pp
Bieniawski,
rock engineering
Classification in
4th International
2, pp.
Vol.
from
and Mining
of Rock Mechanics
for Rock Mechanics,
Society
Z. T.
Bieniawski,
Journal
experience
deformability:
Congress on Rock Mechanics,
Montreux, A. A.
Balkema,
state
art
51-58.
classifications
of the
Transportation Research Record, No.
783,
and need Washington,
2-9. Z. T.
Rock Mechanics
in Mining and Tunneling,
Design
p.
A. A. Balkema Publishers, Rotterdam/Boston, 1984, 27
Cameron-Clarke, I. S. and Budavari, S. Correlation of rock mass in situ observations. classification parameters obtained from borecore an Vol.
Engineering Geology.,
9.
Estimate
237-248.
pp.
Proceedings,
Rotterdam, 1979,
8.
Assess-
Construction, Laboratorio
Underground
Determining rock mass
Z. T.
Bieniawski,
International
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and
Civil, Lisbon, Portugal,
International
histories.
applications.
6.
Rock
11-51-11-70.
Sciences,
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for
University of
Thesis,
Proceedings.
Deformability of Rock Masses.
de Engenharia
Bieniawski, case
Society
233 p.
Symposium on Engineering Geology Nacional
5t
Application to
and It
Characterization
of
E15-E19.
pp.
Application of Q-System and Index Tests
Strength and
pp.
Proceedings,
International
1983,
E.
the Convergence
Predict
of Unsupported Underground Openings, Ph.D.
Melbourne,
3.
Rock Mass
and Hildago,
Supports.
Designer
Australia, April,
Melbourne,
Baczynski, N. ment
and to
Congress of Rock Mechanics,
International Mechanics,
Gutierrez, V.
E.,
Chacon,
De Vallejo, L. I.
17
1981,
pp.
19-53.
New Rock Classification
Assessment Using Surface
Data.
Proceedings.
System
for Underground
International
Symposium on
Engineering Geology and Underground Construction, Laboratorio Nacional Engenharia Civil, pp.
10
Lisbon, Portugal, September
Geotechnical
Rapid Excavation and
design
of large openings
Tunneling Conference,
Metallurgical, and Petroleum
11.
De
I,
Vol.
11-85-11-94.
Hoek, E.
pp.
1983,
Engineers,
at
depth.
Proceedings,
American Institute of Mining,
New York,
1981,
Vol.
2,
1167-1185.
Kendorski, Rock mass
F. S.,
A.
Bieniawski,
classification for block caving
Proceedings, Society
Cummings, R.
15th International Congress
for Rock Mechanics,
Melbourne,
D2
mine
Z. T., drift
and Skinner, E. H. support.
on Rock Mechanics,
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pp.
B101-113.
International
12.
Hoek, E. an Brown, E. T. Empirical strength criterion fo rock masses. Journal of Geotechnical Engineering, American Society of Civil Engineers, Vol. 106, NO GT9, September 1980, pp. 1013-1035.
13.
Hoek, E. and Brown, E. T. Underground Excavations of Mining an Metallurgy, London, 1980, 527 p.
14.
Priest, S. D. an Brown, E. T. Probabilistic stability analysis of variable rock slopes. Transactions of th Institute of Mining an Metallurgy, London, Section A, Vol. 92, 1983, pp. 1-12.
15.
Brown, E. T. an Hoek, E. "Determination of Shear Failure Envelope in Rock Masses, Discussion." Journal of Geotechnical Engineering, American Society of Civil Engineers, 1988, Vol. 371-373. pp
16.
Hoek, E. an Brown, E. T. 1988 Update of th Hoek an Brown Failure Criterion. 1988 Canadian Rock Mechanics Symposium, In Publication.
17.
Serafim, J. L. an Pereira, J. P. Considerations of Geomechanics Classification of Bieniawski. Proceedings, International Symposium on Engineering Geology an Underground Construction, Laboratorio Nacional De Engenharia Civil, Lisbon, Portugal, 1983, pp 11-33-11-42.
18.
Moreno-Tallon, E. Comparison an application of geomechanics classification schemes in tunnel construction. Proceedings, Tunneling '83 Conference, Institution of Mining an Metallurgy, London, 1982, pp. 241-146.
19.
Unal, E. Design Guidelines an Roof Control Standards fo Coal Mine Roofs. Ph.D. Thesis, Th Pennsylvania State University, 1983, 355 p.
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Priest, S. D. an Hudson, J. A. Discontinuity spacing in rock. International Journal of Rock Mechanics an Mining Sciences, Vol. 13, 1979, pp 135-198.
D23
in Rock, Institution
