Rock Mass Classifications
Marek Cała
Wydział Górnictwa i Geoinżynierii
Katedra Geomechaniki, Budownictwa i Geotechniki
Rock Mass Classification
• Why?
• How does this help
us in tunnel design?
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Interaction
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Summary of rock mass characteristics, testing
methods and theoretical considerations
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Triaxial testing
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
piaskowiec wapień iłowiec
c [Pa] 1,6977E+07
F [
0
]
37,68
c [Pa]
2,7020E+07
F [
0
]
34,48
c [Pa]
2,1791E+07
F [
0
]
33,58
Sandstone Limestone Mudstone
Triaxial testing
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
0
10
20
30
40
50
60
70
80
90
100
Naprężenie średnie, MPa
0
10
20
30
40
50
60
N
a
o
rę
że
n
ie
d
e
w
ia
to
ro
w
e
.
M
P
a
kohezja 4,09 MPa
kąt tarcia 36,84
o
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Types of failure which occur in rock masses
under low and high in-situ stress levels
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Types of failure which occur in rock masses
under low and high in-situ stress levels
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Terrina
Engineering Rock Mass Classification
Schemes
• Developed for estimation of tunnel support
• Used at project feasibility and preliminary design
stages
• Simple check lists or detailed schemes
• Used to develop a picture of the rock mass and its
variability
• Used to provide initial empirical estimates of tunnel
support requirements
• Are practical engineering tools which force the user to
examine the properties of the rock mass
• Do Not replace detailed design methods
• Project specific
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Terzaghi’s Rock Mass Classification
(1946)
• Rock Mass Descriptions
– Intact
– Stratified
– Moderately jointed
– Blocky and Seamy
– Crushed
– Squeezing
– Swelling
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
• Intact rock contains neither joints nor hair cracks. Hence, if it
breaks, it breaks across sound rock. On account of the injury
to the rock due to blasting, spalls may drop off the roof
several hours or days after blasting. This is known as a
spalling condition. Hard, intact rock may also be encountered
in the popping condition involving the spontaneous and
violent detachment of rock slabs from the sides or roof.
• Stratified rock consists of individual strata with little or no
resistance against separation along the boundaries between
the strata. The strata may or may not be weakened by
transverse joints. In such rock the spalling condition is quite
common.
• Moderately jointed rock contains joints and hair cracks, but
the blocks between joints are locally grown together or so
intimately interlocked that vertical walls do not require
lateral support. In rocks of this type, both spalling and
popping conditions may be encountered.
Terzaghi’s Rock Mass Classification
(1946)
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
• Blocky and seamy rock consists of chemically intact or almost
intact rock fragments which are entirely separated from each
other and imperfectly interlocked. In such rock, vertical walls
may require lateral support.
• Crushed but chemically intact rock has the character of crusher
run. If most or all of the fragments are as small as fine sand
grains and no recementation has taken place, crushed rock below
the water table exhibits the properties of a water-bearing sand.
• Squeezing rock slowly advances into the tunnel without
perceptible volume increase. A prerequisite for squeeze is a high
percentage of microscopic and sub-microscopic particles of
micaceous minerals or clay minerals with a low swelling capacity.
• Swelling rock advances into the tunnel chiefly on account of
expansion. The capacity to swell seems to be limited to those
rocks that contain clay minerals such as montmorillonite, with a
high swelling capacity.
Terzaghi’s Rock Mass Classification (1946)
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Quality Designation Index (RQD)
(Deere et al. 1967)
• Aim : to provide a quantitative estimate of rock mass
quality from drill logs
• Equal to the percentage of intact core pieces longer
than 100mm in the total length of core
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
RQD
• Directionally dependant parameter
• Intended to indicate rock mass quality in-situ
• Adapted for surface exposures as ‘J
v
’ number of
discontinuities per unit volume
• Used as a component in the RMR and Q systems
• Palmstrom (1982)
• Priesta i Hudsona (1976)
l - number of joints per unit length
v
J
RQD
3
.
3
115
1
.
0
1
.
0
1
100
e
RQD
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Procedure for Measurement and
Calculation of RQD
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Weathering of Basalt with depth
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Multi parameter Rock Mass Classification
Schemes
• Rock Mass Structure Rating (RSR)
• Rock Mass Rating (RMR)
• Rock Tunnelling Quality Index (Q)
• Geological Strength Index (GSI)
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Mass Structure Rating (RSR) (1972)
• Introduced the concept of rating components to arrive at
a numerical value
• Demonstrates the logic in a quasi-quantitative rock mass
classification
• Has limitations as based on small tunnels supported by
steel sets only
• RSR = A + B + C
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Structure Rating
Parameter A: General area geology
Considers
(a) rock type origin
(b) rock ‘hardness’
(c) geotechnical structure
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Considers
(a) joint spacing
(b) joint orientation (strike and dip)
(c) direction of tunnel drive
Rock Structure Rating
Parameter B: Geometry : Effect of
discontinuity set
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Considers
(a) overall rock mass quality (on the basis of A + B)
(b) joint condition
(c) water inflow
Rock Structure Rating
Parameter C: Groundwater, joint condition
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
RSR support estimates for a 7.3m diameter
circular tunnel
(After Wickham et al. 1972)
Examples
RSR = 62
2” shotcrete
1” rockbolts @
5ft centres
RSR = 30
5” shotcrete
1” rockbolts @
2.5ft centres
OR 8WF31 steel
sets @ 3ft centres
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Geomechanics Classification or
Rock Mass Rating System (RMR)
(Bieniawski 1976)
Based upon
• uniaxial compressive strength of rock material
• rock quality designation (RQD)
• spacing of discontinuities
• condition of discontinuities
• groundwater conditions
• orientation of discontinuities
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
• Rock mass divided into structural regions
• Each region is classified separately
• Boundaries can be rock type or structural, eg: fault
• Can be subdivided based on significant changes, eg:
discontinuity spacing
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Bieniawski, 1976 to 1989
• System refined by greater data
• Ratings for parameters changed
• Adapted by other workers for different situations
• PROJECT SPECIFIC SYSTEMS
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rating
Class
Description
81-100
I
Very Good Rock
61-80
II
Good Rock
41-60
III
Fair Rock
21-40
IV
Poor Rock
Less than 20
V
Very Poor Rock
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Guidelines for excavation and support of 10m
span rock tunnels in accordance with the RMR
system
(After Bieniawski 1989)
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Prediction of in-situ deformation modulus E
m
from rock mass classifications
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
• Nicholson & Bieniawski (1990)
• Bieniawski (1978) and Serafim & Pereira (1983)
• Hoek i Brown (1997)
•Read et al. (1999)
)
82
.
22
/
(
2
9
.
0
0028
.
0
RMR
s
rm
e
RMR
E
E
)
(
50
100
2
GPa
RMR
for
RMR
E
m
)
(
50
10
40
/
)
10
(
GPa
RMR
for
E
RMR
m
40
/
)
10
(
10
10
RMR
c
m
R
E
3
10
1
.
0
RMR
E
mass
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Prediction of in-situ deformation modulus
E
m
from rock mass classifications
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Support pressure - Unal (1983)
s - tunnel width
s
RMR
p
v
100
100
Hoek (1994):
m m e
i
RMR
100
28
s e
RMR
100
9
m
i
- constant – from 4 (weak shales) to 32 (granite).
R
sR
crm
c
R
R
m
m
s
rrm
c
2
4
2
Aydan & Kawamoto (2000)
5
.
2
0016
.
0
RMR
R
crm
Kalamaras & Bieniawski (1995)
85
15
2
RMR
R
R
c
crm
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Trueman (1988):
RMR
cmass
e
06
.
0
5
.
0
Yudhbir (1983):
RMR
RMR
ci
cmass
e
100
65
.
7
Sheorey (1997):
20
100
RMR
ci
cmass
e
Rock Mass Rating System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Mass Rating System
Aydan & Kawamoto (2000)
RMR
RMR
RMR
R
R
c
crm
100
6
Let’s assume:
60
RMR
MPa
R
c
80
Hoek:
Aydan:
Kalamaras & Bieniawski:
MPa
R
c
67
.
8
MPa
R
c
62
.
44
MPa
R
c
18
.
21
Aydan & Kawamoto (2000)
RMR
rm
05
.
0
22
rm
rm
crm
rm
R
c
cos
sin
1
2
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Tunnelling Quality Index Q – Barton,
Lien, Lunde
• Based on case histories in Scandinavia
• Numerical values on a log scale
• Range 0.001 to 1000
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
‘Q’ Classification System
(After Barton et al. 1974)
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
• represents the structure of the rockmass
• crude measure of block or particle size
(After Barton et al. 1974)
‘Q’ Classification System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
• represents roughness and frictional
characteristics of joint walls or infill material
(After Barton et al. 1974)
‘Q’ Classification System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
• consists of two stress parameters
• SRF can be regarded as a total stress parameter
measure of
– loosening load as excavated through shear zones
– rock stress in competent rock
– squeezing loads in plastic incompetent rock
• J
W
is a measure of water pressure
(After Barton et al. 1974)
‘Q’ Classification System
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Classification of individual parameters
used in
the Tunnelling Quality Index Q
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Classification of individual parameters used
in
the Tunnelling Quality Index Q (cont’d)
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
JRC=Joint Roughness Coefficient
Classification of individual parameters used in
the Tunnelling Quality Index Q
(cont’d)
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
‘Q’ Classification System – SRF update
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Q Classification Scheme
Resolves to three parameters
• Block size
( RQD / J
n
)
• Interblock shear strength ( J
r
/ J
a
)
• Active stress
( J
w
/ SRF )
• Does NOT include joint orientation
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Equivalent Dimension D
e
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Estimated support categories based on the
tunnelling quality index Q
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Q Classification Scheme
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Q - rock mass properties
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Q - rock mass properties
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Q - rock mass properties
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Q Classification Scheme
Roof pressure:
3
1
Q
J
J
p
r
n
roof
Length of the bolts:
(roof)
(walls)
ESR
s
L
15
.
0
2
3
1
3
2
.
0
Q
J
J
p
r
n
roof
Bhasin & Grimstad (1996):
3
1
40
Q
J
s
p
r
roof
Young’s modulus:
Seismic wave velocity:
]
/
[
100
log
5
.
3
s
km
R
Q
V
c
p
L
H
ESR
2 0 15
.
GPa
R
Q
E
c
3
3
3
10
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
RMR – Q - Correlations
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
RMR – Q -Correlations
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Mass Classification System
• RMR and Q system or variants are the most widely
used
• both incorporate geological, geometric and
design/engineering parameters to obtain a “value” of
rock mass quality
• empirical and require subjective assessment
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Rock Mass Classification System
Approach:
• accurately characterise the rockmass ie: full and
complete description of the rockmass
• assign parameters for classification later
• always use two systems for comparison
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Geological Strength Index (GSI)
• Method to link the constants m and s of Hoek-Brown
failure criterion to observations in the field
ie: a possible solution to the problem of estimating
strength of jointed rock mass
• A system for estimating the reduction in rock mass
strength for different geological conditions
• Overcomes deficiencies of RMR for poor quality rock
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Estimate of Geological Strength
Index GSI
based on geological
descriptions
Estimation of constants based upon
rock
mass structure and discontinuity
surface conditions
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Geological Strength Index (GSI)
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Geological Strength
Index (GSI)
Estimate of Geological
Strength Index GSI
based on geological
descriptions.
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Plots of cohesive strength and friction angles
for different GSI and m
i
values
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Klasyfikacja KF
Marek Cała, Katedra Geomechaniki, Budownictwa i Geotechniki, WGiG AGH, Kraków
Wyszukiwarka
Podobne podstrony:
Klasyfikacja węgla, A.PDF
Formalno prawne aspekty dzialalnoości geologiczno górniczej klasyfikacja zasobów
Podmiotowa klasyfikacja zjawisk finansowych
Podstawy rachunkowości Klasyfikacja kont 2
Sygnały klasyfikacja
klasyfikacja i etiopatogeneza zaburzen seksualnych
2 Urazy zębów u pacjentów dorosłych klasyfikacje (2)id 19701 ppt
INSTR KLASYF DLUZNE
14 TIOB W14 zelbet i klasyfikacja deskowan
instr 2011 pdf, Roztw Spektrofoto
Klasyfikacja bakterii i mechanizmy patogenezy bakteryjnej
(ebook PDF)Shannon A Mathematical Theory Of Communication RXK2WIS2ZEJTDZ75G7VI3OC6ZO2P57GO3E27QNQ
KSIĄŻKA OBIEKTU pdf
więcej podobnych podstron