ISO 22932-3:2023

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 22932-3
ISO/TC 82
Mining – Vocabulary —
Secretariat: DIN
Voting begins on:
Part 3:
2023-03-03
Rock mechanics
Voting terminates on:
2023-04-28
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BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 22932-3:2023(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2023

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ISO/FDIS 22932-3:2023(E)
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 22932-3
ISO/TC 82
Mining – Vocabulary —
Secretariat: DIN
Voting begins on:
Part 3:
Rock mechanics
Voting terminates on:
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© ISO 2023
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IN ADDITION TO THEIR EVALUATION AS
Reference number
Email: copyright@iso.org
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 22932-3:2023(E)
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LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
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OCCASION HAVE TO BE CONSIDERED IN THE
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ii
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NATIONAL REGULATIONS. © ISO 2023

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ISO/FDIS 22932-3:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 1
3.2 Stress . 2
3.3 Strain . 7
3.4 Both stress and strain . 9
3.5 Rock mass .12
3.6 Discontinuity . 16
3.7 Anisotropy and inhomogeneity . 25
3.8 Mechanical behaviour of rock . 26
3.9 Physical properties of rock . 31
Bibliography .37
Index .38
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ISO/FDIS 22932-3:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 82, Mining.
A list of all parts in the ISO 22932 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
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ISO/FDIS 22932-3:2023(E)
Introduction
The ISO 22932 series has been prepared in order to standardize and to coordinate the global use of
technical terms and definitions in mining, for the benefit of the experts working on different types of
mining activities.
The need for the ISO 22932 series arose from the widely varying interpretation of terms used within
the industry and the prevalent use of more than one synonym.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 22932-3:2023(E)
Mining – Vocabulary —
Part 3:
Rock mechanics
1 Scope
This document specifies the rock-mechanics terms commonly used in mining. Only those terms that
have a specific meaning in this field are included.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 General terms
3.1.1
abrasion
rubbing and wearing away
[SOURCE: Reference [1], 235]
3.1.2
angle of repose
maximum angle with respect to the horizontal plane that the surface of a pile of a loose material will
assume
[SOURCE: Reference [1], 3]
3.1.3
erosion
process whereby soil or rock mass (3.5.25) is loosened or dissolved and removed from any part of the
earth's surface
Note 1 to entry: It includes weathering (3.1.8), solution and transportation.
[SOURCE: IS 11358:1987, 2.109, modified — Note 1 to entry was originally part of the definition]
3.1.4
incompetent rock
rock (3.1.5) incapable of standing in underground opening or steep slopes at the surface without
support
[SOURCE: IS 11358:1987, 2.155]
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ISO/FDIS 22932-3:2023(E)
3.1.5
rock
solid material forming as part of the earths’ crust
3.1.6
rock material
smallest element of rocks (3.1.5) not cut by any fracture (3.6.20)
Note 1 to entry: There are always some micro-fractures in the rocks (3.1.5) material.
[SOURCE: IS 11358:1987, 2.253, modified — Note 1 to entry was originally part of the definition.]
3.1.7
rock mechanics
theoretical and applied science of the mechanical behaviour of rock (3.1.5)
[SOURCE: Reference [1], 9]
3.1.8
weathering
process of disintegration and decomposition as a consequence of exposure to the atmosphere, to
chemical action, and to the action of frost, water, and heat
[SOURCE: Reference [1], 99]
3.2 Stress
3.2.1
biaxial compression
compression caused by the application of normal stresses (3.2.20) in two perpendicular directions
[SOURCE: Reference [1], 20]
3.2.2
biaxial state of stress
state of stress (3.2.29) in which one of the three principal stresses (3.2.29) is zero
[SOURCE: Reference [1], 33]
3.2.3
coefficient of friction
μ
relating normal stress (3.2.20) and the corresponding critical shear stress (3.2.27) at which sliding
(3.8.36) starts between two surfaces as follows:
τ = μ·σ
where
τ is the shear stress;
μ is the coefficient of friction;
σ is the normal stress.
[SOURCE: Reference [1], 1]
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ISO/FDIS 22932-3:2023(E)
3.2.4
cohesion
shear resistance at zero normal stress (3.2.20)
Note 1 to entry: An equivalent term in rock mechanics (3.1.7) is intrinsic shear strength (3.9.31).
Note 2 to entry: Compare with cohesion (3.9.8).
[SOURCE: Reference [1], 72, modified — Note 1 to entry was originally part of the definition.]
3.2.5
competent ground
rock mass (3.5.25) strength (3.9.31) which is higher than the ground stresses (3.2.29) imposed
Note 1 to entry: See Reference [4].
3.2.6
compressive stress
normal stress (3.2.20) tending to shorten the body in the direction in which it acts
[SOURCE: Reference [1], 50]
3.2.7
critical stress
maximum and minimum compressive stress (3.2.6) on the boundary of an opening
[SOURCE: IS 11358:1987, 2.75]
3.2.8
cyclical stress
stress (3.2.29) produced by repeated stressing and de-stressing
[SOURCE: IS 11358:1987, 2.82, modified — The phrase "stress produced" has been added and "of
material" was originally part of the definition.]
3.2.9
dilatancy
property of volume increase under loading
[SOURCE: Reference [1], 75]
3.2.10
effective stress
pore water pressure (3.9.20) in rock (3.1.5) as a factor affecting rock (3.1.5) strength (3.9.31)
Note 1 to entry: The effective normal stress (3.2.20) is generally taken equal to the difference between normal
stress and the pore water pressure.
Note 2 to entry: This is strictly valid only where pores, cracks (3.6.11) and fractures (3.6.20) are interconnected.
[SOURCE: IS 11358:1987, 2.107, modified — Notes 1 and 2 to entry were originally part of the definition.]
3.2.11
finite element
one of the regular geometrical shapes into which a figure is subdivided for the purpose of numerical
stress (3.2.29) analysis
[SOURCE: Reference [1], 17]
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ISO/FDIS 22932-3:2023(E)
3.2.12
hydraulic fracturing
method to measure the principal stress (3.2.29) situation by fracturing of the rock (3.1.5) surrounding
a section of a drill hole
Note 1 to entry: The fracture (3.6.20) is obtained using increasing water pressure.
Note 2 to entry: See Reference [4].
3.2.13
hydrostatic pressure
state of stress (3.2.29) in which all the principal stresses (3.2.29) are equal (and there is no shear stress
(3.2.27)
[SOURCE: Reference [1], 48]
3.2.14
incompetent ground
overstressed rock masses (3.5.25)
Note 1 to entry: See Reference [4].
3.2.15
inelastic deformation
portion of deformation (3.8.13) under stress (3.2.29) that is not annulled by removal of stress (3.2.29)
[SOURCE: Reference [1], 67]
3.2.16
keelformed overbreak
characteristic shape of overbreak caused by high, anisotropic rock (3.1.5) stress (3.2.29)
Note 1 to entry: See Reference [4].
3.2.17
Kirsch's equation
equation, which may be used for evaluating the tangential stresses (3.2.29) around tunnels and other
underground openings
Note 1 to entry: See Reference [4].
3.2.18
k-value
ratio between horizontal and vertical stresses (3.2.29) within the rock mass (3.5.25)
Note 1 to entry: See Reference [4].
3.2.19
Mohr’s envelope
envelope of a sequence of Mohr’s circles representing stress (3.2.29) conditions at failure (3.6.15) for a
given material
[SOURCE: Reference [1], 12]
3.2.19.1
angle of internal friction
angle of shear resistance
angle, ϕ, (degrees) between the axis of normal stress (3.2.20) and the tangent to the Mohr’s envelope
(3.2.19) at a point representing a given failure (3.6.15)-stress (3.2.29) condition for solid material
[SOURCE: Reference [1], 2]
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ISO/FDIS 22932-3:2023(E)
3.2.20
normal stress
stress (3.2.29) in a rock (3.1.5) perpendicular to the shear stress (3.2.27)
[SOURCE: IS 11358:1987, 2.203, modified — The phrase "(normal)” was removed of the definition]
3.2.21
primary state of stress
state of stress (3.2.29) in a geological formation before it is disturbed by an opening
Note 1 to entry: Adapted from Reference [1], 46.
3.2.22
primitive stress
virgin rock stress
ground which is in a state of equilibrium before excavation of a tunnel or any underground opening
Note 1 to entry: At this stage, the stresses (3.2.29) at any point within the ground are termed as “primitive”,
“primary” or “pre-excavation” stresses (3.2.29).
[SOURCE: IS 11358:1987, 2.234, modified — Note 1 to entry was originally part of the definition.]
3.2.23
plasticity
property of a material to continue to deform indefinitely while sustaining a constant stress (3.2.29)
[SOURCE: Reference [1], 94]
3.2.24
relaxation
rate of reduction of stress (3.2.29) in a material due to creep (3.8.10)
Note 1 to entry: An alternate term is stress (3.2.29) relaxation.
[SOURCE: IS 11358:1987, 2.240, modified — Note 1 to entry was originally part of the definition.]
3.2.25
residual stress
stress (3.2.29) remaining in a solid under zero external stress (3.2.29) after some process that causes
the dimensions of the various parts of the solid to be incompatible under zero stress (3.2.29)
EXAMPLE 1 Deformation (3.8.13) under the action of external stress (3.2.29) when some parts of the body
suffer permanent strain (3.3.7).
EXAMPLE 2 Heating or cooling of a body in which the thermal expansion coefficient is not uniform throughout
the body.
[SOURCE: Reference [1], 49, modified — EXAMPLES 1 and 2 to entry were originally part of the
definition.]
3.2.26
secondary state of stress
resulting state of stress (3.2.29) in the rock (3.1.5) around an opening
[SOURCE: Reference [1], 47, adapted]
3.2.27
shear stress
stress (3.2.29) directed parallel to the surface element across which it acts
[SOURCE: Reference [1], 51]
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ISO/FDIS 22932-3:2023(E)
3.2.28
stability
condition of a structure or a mass of material when it is able to support the applied stress (3.2.29) for
a long time without suffering any significant deformation (3.8.13) or movement that is not reversed by
the release of stress
[SOURCE: Reference [1], 15]
3.2.29
stress
force acting across a given surface element, divided by the area of the element as follows:
F
v
σ=
A
F
h
τ=
A
where
σ is the normal stress (3.2.20);
τ is the shear stress (3.2.27);
F is the vertical force;
v
F is the horizontal force;
h
A is the area of element.
[SOURCE: Reference [1], 66]
3.2.30
stress concentration factor
ratio of tangential stress (3.2.29) at a particular point along the periphery and the initial stress before
excavation at that point
Note 1 to entry: Stress concentration takes place when a cavity is excavated in a rock mass (3.5.25).
Note 2 to entry: The higher the stress concentration factor, the greater are the chances of failure (3.6.15) of the
rock mass or rock burst (3.8.30).
[SOURCE: IS 11358:1987, 2.311, modified — Notes 1 and 2 to entry were originally part of the definition.]
3.2.31
stress ellipsoid
representation of the state of stress (3.2.29) in the form of an ellipsoid whose semi-axes are proportional
to the magnitudes of the principal stresses and lie in the principal directions
Note 1 to entry: The coordinates of a point P on this ellipse are proportional to the magnitudes of the respective
components of the stress across the plane normal to the direction OP, where O is the centre of the ellipsoid.
[SOURCE: Reference [1], 5, modified — Note 1 to entry was originally part of the definition.]
3.2.32
tensile stress
normal stress (3.2.20) tending to lengthen the body in the direction in which it acts
[SOURCE: Reference [1], 52]
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ISO/FDIS 22932-3:2023(E)
3.2.33
thermal stress
internal stress (3.2.29), caused in part by uneven heating
[SOURCE: IS 11358:1987, 2.327]
3.2.34
triaxial compression
compression caused by the application of normal stresses (3.2.20) in three perpendicular directions
[SOURCE: Reference [1], 21]
3.2.35
triaxial state of stress
state of stress (3.2.29) in which none of the three principal stresses is zero
[SOURCE: Reference [1], 24]
3.2.36
uniaxial compression
unconfined compression
compression caused by the application of normal stress (3.2.20) in a single direction
[SOURCE: Reference [1], 19]
3.2.37
uniaxial state of stress
state of stress (3.2.29) in which two of the three principal stresses are zero
[SOURCE: Reference [1], 22]
3.2.38
yield stress
stress (3.2.29) beyond which the induced deformation (3.8.13) is not fully annulled after complete
distressing
[SOURCE: Reference [1], 68]
3.3 Strain
3.3.1
brittleness
material condition characterised by reduced ability to carry load as the strain (3.3.11) increases
Note 1 to entry: See Reference [4].
3.3.2
contraction
linear strain (3.3.11) associated with a decrease in length
[SOURCE: Reference [1], 25]
3.3.3
ductility
condition in which material can sustain permanent deformation (3.8.13) without losing its ability to
resist load, or on the other hand for a known or particular stress (3.2.29) state (existing or imposed) to
which a material can sustain plastic deformation (3.8.26) without breaking (3.6.7) or rupture (3.6.30)
Note 1 to entry: Elongation and reduction of area are common indices of ductility.
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ISO/FDIS 22932-3:2023(E)
3.3.4
elastic strain energy
potential energy stored in a strained solid and equal to the work done in deforming the solid from its
unstrained state less any energy dissipated by inelastic deformation (3.2.15)
[SOURCE: Reference [1], 7]
3.3.5
extension
linear strain (3.3.11) associated with an increase in length
[SOURCE: Reference [1], 30]
3.3.6
normal strain
change in length per unit of length in a given direction
[SOURCE: Reference [1], 35]
3.3.7
permanent strain
strain (3.3.11) remaining in a solid state with respect to its initial condition after the application and
removal of stress (3.2.29) greater than the yield stress (3.2.38)
Note 1 to entry: Commonly also called “residual strain” (3.3.8).
[SOURCE: Reference [1], 38, modified — "solid" has been replaced by "solid state".]
3.3.8
residual strain
strain (3.3.11) in a solid state associated with a state of residual stress (3.2.25)
[SOURCE: Reference [1], 37, modified — "solid" has been replaced by "solid state".]
3.3.9
shear strain
change in shape, expressed by the relative change of the right angles at the corner of what was in the
undeformed state an infinitesimally small rectangle or cube
[SOURCE: Reference [1], 36]
3.3.10
simple shear
shear strain (3.3.9) in which displacements (3.8.17) all lie in one direction and are proportional to the
normal distances of the displaced points from a given reference plane
Note 1 to entry: The dilatation (3.8.15) is zero.
[SOURCE: Reference [1], 34, modified — Note 1 to entry was originally part of the definition.]
3.3.11
strain
relative elongation or shortening of a material as result of loading
Note 1 to entry: See Reference [4].
3.3.12
strain ellipsoid
representation of the strain (3.3.11) in the form of an ellipsoid into which a sphere of unit radius deforms
and whose axes are the principal axes of strain
[SOURCE: Reference [1], 6]
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ISO/FDIS 22932-3:2023(E)
3.3.13
strain energy release rate
rate of strain (3.3.11) energy released per unit area of the excavated surface in the underground minor
tunnel openings
Note 1 to entry: If the strain energy release rate is more than a limiting value, rock burst (3.8.30) is likely to occur.
[SOURCE: IS 11358:1987, 2.306, modified — Note 1 to entry was originally part of the definition.]
3.3.14
strain hardening
material that is loaded beyond the yield point within the inelastic domain above the yield point
Note 1 to entry: Its state of matter is shown by continuous rise of the stress (3.2.29)-strain (3.3.11) curve.
Note 2 to entry: Adapted from IS 11358:1987, 2.307.
3.3.15
strain softening
during uniaxial or triaxial testing of rocks (3.1.5), it is generally observed that strength (3.9.31)
decreases after certain strain (3.3.11)
[SOURCE: IS 11358:1987, 2.308]
3.3.16
viscoelasticity
property of materials that strain (3.3.11) under stress (3.2.29) partly elastically and partly viscously,
that is, whose strain is partly dependent on time and magnitude of stress
[SOURCE: Reference [1], 95]
3.4 Both stress and strain
3.4.1
Young's modulus
modulus of elasticity
axial Young's modulus
E
ratio of the axial stress (3.2.29) change to the axial strain (3.3.11) produced by the stress change for a
cylindrical specimen tested in uniaxial compression (3.2.36)
Note 1 to entry: It may be calculated using any of the following methods.
a) Tangential Young's modulus, E — This is the tangential Young's modulus at a stress level which is some
T
fixed percentage of the ultimate strength (3.9.31) and is generally 50 % of the ultimate uniaxial compressive
strength (3.9.10).
b) Average Young's modulus, E — The average Young's modulus is defined as the average slope of more or less
ar
straight portion of the axial stress-strain curve.
c) Secant Young's modulus, E — The secant Young's modulus is usually measured from zero stress to some
s
fixed percentage of the ultimate strength, generally 50 %.
[SOURCE: IS 11358:1987, 2.19, modified — Note 1 to entry was originally part of the definition and
"modulus of elasticity" and "Young's modulus" were added as equivalent terms.]
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ISO/FDIS 22932-3:2023(E)
3.4.2
deviator of stress
deviator of strain
stress (3.2.29)/strain (3.3.11) tensor obtained by subtracting the mean of the normal stress (3.2.20)/
strain components of a stress/strain tensor from each normal stress/strain component
[SOURCE: Reference [1], 4]
3.4.3
deformation modulus
E
c
ratio of stress (3.2.29), σ to the total strain (3.3.11), in repeated loading-unloading tests, as follows:
σσ
E ==
c
∈∈ +∈
totalelir
where
E is the deformation modulus;
C
σ is the normal stress;
Є is the elastic strain;
el
Є is the irreversible strain.
ir
Note 1 to entry: This modulus is thus based on the total measured strains, that is, elastic plus inelastic
(irreversible or plastic) strains, Є and Є , respectively.
el ir
Note 2 to entry: Total strain = Є + Є .
el ir
[SOURCE: IS 11358:1987, 2.86, modified — Notes 1 and 2 to entry were originally part of the definition.]
3.4.4
modulus ratio
ratio between the Young's modulus (3.4.1) and the uniaxial compressive strength (3.9.10)
Note 1 to entry: The higher the value of the modulus ratio, the more brittle (3.8.4) is the rock (3.1.5).
Note 2 to entry: The rock material (3.1.6) is classified as high, medium and low modulus ratio for modulus ratios
of > 500, 500-200 and < 200 respectively.
[SOURCE: IS 11358:1987, 2.194]
3.4.5
modulus reduction factor
M
RF
ratio between static elastic modulus of rock mass (3.5.25) (E or estatic) obtained from in-situ tests and
the elastic modulus of rock (3.1.5) matter {E ) obtained from, laboratory test
r
[SOURCE: IS 11358:1987, 2.195]
3.4.6
Mohr’s circle of stress
Mohr’s circle of strain
graphical representation of the components of stress (3.2.29)/strain (3.3.11) acting across the various
planes at a given point, drawn with reference to axes of normal stress (3.2.20)/strain and shear stress
(3.2.27)(strain)
[SOURCE: Reference [1], 11]
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ISO/FDIS 22932-3:2023(E)
3.4.7
plane stress
plane strain
state of stress (3.2.29) (strain (3.3.11)) in a solid body in which all stress (strain) components normal to
a certain plane are zero
[SOURCE: Reference [1], 31]
3.4.8
Poisson’s ratio
ratio of the shortening in the transverse direction to the elongation in the direction of an applied force
in a body under tension below the proportional limit
[SOURCE: Reference [1], 100]
3.4.9
principal stress
principal strain
stress (3.2.29) (strain (3.3.11)) normal to one of three mutually perpendicular planes on which the shear
stresses (3.2.27) (strains) at a point in a body are zero
[SOURCE: Reference [1], 32]
3.4.10
pure shear
state of strain (3.3.11) resulting from that stress (3.2.29) condition most easily described by a Mohr
circle centred at the origin
[SOURCE: Reference [1], 33]
3.4.11
secant modulus
slope of the line connecting the origin and a given point on the stress (3.2.29)-strain (3.3.11) curve
[SOURCE: Reference [1], 90]
3.4.12
stress field
strain field
ensemble of stress (3.2.29) (strain (3.3.11)) states defined at all points of an elastic solid
[SOURCE: Reference [1], 8]
3.4.13
stress rate
strain rate
rate of change of stress (3.2.29) (strain (3.3.11)) with time
[SOURCE: Reference [1], 13]
3.4.14
stress tensor
strain tensor
second order tensor whose diagonal elements consist of the normal stress (3.2.20) (strain (3.3.11))
components with respect to a given set of coordinate axes and whose off-diagonal elements consist of
the corresponding shear stress (3.2.27) (strain) components
[SOURCE: Reference [1], 16]
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ISO/FDIS 22932-3:2023(E)
3.4.15
tangent modulus
slope of the tangent to the stress (3.2.29)-strain (3.3.11) curve at a given stress value
Note 1 to entry: Generally taken at a stress equal to half the compressive strength (3.9.10).
[SOURCE: Reference [1], 91, modified — Note 1 to entry was originally part of the definition.]
3.4.16
unloading modulus
slope of the tangent to the unloading stress (3.2.29)-strain (3.3.11) curve at a given stress value
[SOURCE: Reference [1], 92]
3.5 Rock mass
3.5.1
allowable bearing pressure
allowable pressure transmitted by a foundation to the rock mass (3.5.25) such that no damage occurs
either in the structure or in the rock mass
Note 1 to entry: It is based upon safe bearing pressure (3.9.4) (satisfying criteria of shear, total and differential
settlement and tilt), correction factors, and past experience and judgment of experts.
[SOURCE: IS 11358:1987, 2.6, modified — Note 1 to entry was originally part of the definition.]
3.5.2
attenuation
decrease of the amplitude of waves as they travel through rock mass (3.5.25)
Note 1 to entry: This reduction in amplitude is known as attenuation.
Note 2 to entry: Attenuation is energy loss with distance per cycle.
[SOURCE: IS 11358:1987, 2.18, modified — Note
...

ISO/FDIS 22932-3:20XX(E)
ISO/TC 82/WG 8
Secretariat: DIN
Date: 2023-02-17
Mining —– Vocabulary —
Part 3:
Rock Mechanicsmechanics
DIS

Warning for DIS
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Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of
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FDIS stage

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© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this
publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical,
including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can
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ISO/FDIS 22932-3 -20XX:2023(E)
Page
Contents
Foreword……………………………………………………………………………………………………………………………………… iv
……………
Introduction………………………………………………………………………………………………………………………………… v
………………
Scope…………………………………………………………………………………………………………………………………… 1
1
……………
Normative 1
2
references…………………………………………………………………………………………………………………………
Terms and 1
3
definitions…………………………………………………………………………………………………………………………
General 1
3.1
terms……………………………………………………………………………………………………………………………
Stress…………………………………………………………………………………………………………………………… 2
3.2
……………
Strain…………………………………………………………………………………………………………………………… 9
3.3
……………
Both stress and 11
3.4
strain…………………………………………………………………………………………………………………
Rock 14
3.5 mass……………………………………………………………………………………………………………………………
……
Discontinuity 20
3.6
……………………………………………………………………………………………………………………………
Anisotropy and 31
3.7
inhomogeneity……………………………………………………………………………………………………
Mechanical behaviour of 32
3.8
rock……………………………………………………………………………………………………
Physical properties of rock 38
3.9
………………………………………………………………………………………………………
Bibliography…………………………………………………………………………………………………………………………………… 46
………………
Bibliography………………………………………………………………………………………………………………………………… 47
……………



iv © ISO 20xx -2023 – All rights reserved

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ISO/FDIS 22932-3:20XX2023(E)
Contents
Foreword . vi
Introduction .vi i
Part 3: Rock mechanics . 1
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 1
3.2 Stress . 2
3.3 Strain . 8
3.4 Both stress and strain . 10
3.5 Rock mass . 13
3.6 Discontinuity . 18
3.7 Anisotropy and inhomogeneity . 27
3.8 Mechanical behaviour of rock . 28
3.9 Physical properties of rock . 34
Bibliography . 40
Index . 42

© ISO 20XX all2023 – All rights reserved v

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ISO/FDIS 22932-3 -20XX:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO
collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received. (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the World
Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 82, Mining.
A list of all parts in the ISO 22932 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
Field Code Changed
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ISO/FDIS 22932-3:20XX2023(E)
Introduction
The ISO 22932 series has been prepared in order to standardize and to co-ordinatecoordinate the global
use of technical terms and definitions in mining, for the benefit of the experts working on different types
of mining activities.
The need for the ISO 22932 series arose from the widely varying interpretation of terms used within the
industry and the prevalent use of more than one synonym.
© ISO 20XX all2023 – All rights reserved vii

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ISO/FDIS 22932-3:2023(E)
Mining —– Vocabulary —
Part 3:
Rock mechanics
1 Scope
This document specifies the Rock Mechanicsrock-mechanics terms commonly used in mining. Only
those terms that have a specific meaning in this field are included.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
3.1 General terms
3.1.1
abrasion
rubbing and wearing away
[SOURCE: Reference [1ISRM], 235]
3.1.2
angle of repose
maximum angle with respect to the horizontal plane that the surface of a pile of a loose material will
assume
[SOURCE: Reference [1ISRM], 3]
3.1.3
erosion
process whereby soil or rock mass (3.5.25(3.5.25)) is loosened or dissolved and removed from any part
of the earth's surface
Note 1 to entry: It includes weathering (3.1.8(3.1.8),), solution and transportation.
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.109, modified — Note 1 to entry was originally part of
the definition]
3.1.4
incompetent rock
rock (3.1.5(3.1.5)) incapable of standing in underground opening or steep slopes at the surface without
support
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.155]
3.1.5
rock
solid material forming as part of the earths’ crust
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ISO/FDIS 22932-3:2023(E)
3.1.6
rock material
smallest element of rocks (3.1.5(3.1.5)) not cut by any fracture (3.6.20(3.6.20))
Note 1 to entry: There are always some micro-fractures in the rocks (3.1.5(3.1.5)) material.
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.253, modified — Note 1 to entry was originally part of
the definition].]
3.1.7
rock mechanics
theoretical and applied science of the mechanical behaviour of rock (3.1.5()3.1.5)
[SOURCE: Reference [1ISRM], 9]
3.1.8
weathering
process of disintegration and decomposition as a consequence of exposure to the atmosphere, to
chemical action, and to the action of frost, water, and heat
[SOURCE: Reference [1ISRM], 99]
3.2 Stress
3.2.1
biaxial compression
compression caused by the application of normal stresses (3.2.20(3.2.20)) in two perpendicular
directions
[SOURCE: Reference [1ISRM], 20]
3.2.2
biaxial state of stress
state of stress (3.2.29(3.2.29)) in which one of the three principal stresses (3.2.29(3.2.29)) is zero
[SOURCE: Reference [1ISRM], 33]
3.2.3
coefficient of friction
μ
relating normal stress (3.2.20(3.2.20)) and the corresponding critical shear stress (3.2.27(3.2.27)) at
which sliding (3.8.36(3.8.36)) starts between two surfaces as follows:
τ = μ·σ
where
τ is the shear stress;
μ is the coefficient of friction;
σ is the normal stress.
where
 τ is the shear stress;
 μ is the coefficient of friction;
 σ is the normal stress.
[SOURCE: Reference [1ISRM], 1]
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ISO/FDIS 22932-3:2023(E)
3.2.4
cohesion
shear resistance at zero normal stress (3.2.20(3.2.20))
Note 1 to entry: An equivalent term in rock mechanics (3.1.7(3.1.7)) is intrinsic shear strength (3.9.31(3.9.32).).
Note 2 to entry: Compare with cohesion (3.9.8(3.9.8).).
[SOURCE: Reference [1ISRM], 72, modified — Note 1 to entry was originally part of the definition.]
3.2.5
competent ground
rock mass (3.5.25(3.5.25) )strength (3.9.31(3.9.32)) which is higher than the ground stresses
(3.2.29(3.2.29)) imposed
Note 1 to entry: See Reference [4[4].].
3.2.6
compressive stress
normal stress (3.2.20(3.2.20)) tending to shorten the body in the direction in which it acts
[SOURCE: Reference [1ISRM], 50]
3.2.7
critical stress
maximum and minimum compressive stress (3.2.6(3.2.6)) on the boundary of an opening
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.75]
3.2.8
cyclical stress
stress (3.2.29(3.2.29)) produced by repeated stressing and de-stressing
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.82, modified — The phrase "stress produced" has been
added and "of material" was originally part of the definition].]
3.2.9
dilatancy
property of volume increase under loading
[SOURCE: Reference [1ISRM], 75]
3.2.10
effective stress
pore water pressure (3.9.20(3.9.20)) in rock (3.1.5(3.1.5)) as a factor affecting rock (3.1.5(3.1.5)
)strength (3.9.31(3.9.32))
Note 1 to entry: The effective normal stress (3.2.20(3.2.20)) is generally taken equal to the difference between
normal stress (3.2.20) and the pore water pressure (3.9.20).
Note 2 to entry: This is strictly valid only where pores, cracks (3.6.11(3.6.11)) and fractures (3.6.20(3.6.20)) are
interconnected.
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.107, modified — Notes 1 and 2 to entry were originally
part of the definition.]
3.2.11
finite element
one of the regular geometrical shapes into which a figure is subdivided for the purpose of numerical stress
(3.2.29(3.2.29)) analysis
© ISO 20XX -2023 – All rights reserved 3

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ISO/FDIS 22932-3:2023(E)
[SOURCE: Reference [1ISRM], 17]
3.2.12
hydraulic fracturing
method to measure the principal stress (3.2.29(3.2.29)) situation by fracturing of the rock (3.1.5(3.1.5))
surrounding a section of a drill hole
Note 1 to entry: The fracture (3.6.20(3.6.20)) is obtained using increasing water pressure.
Note 2 to entry: See Reference [4[4].].
3.2.13
hydrostatic pressure
state of stress (3.2.29(3.2.29)) in which all the principal stresses (3.2.29(3.2.29)) are equal (and there is
no shear stress (3.2.27(3.2.27))
[SOURCE: Reference [1ISRM], 48]
3.2.14
incompetent ground
overstressed rock masses (3.5.25(3.5.25))
Note 1 to entry: See Reference [4[4].].
3.2.15
inelastic deformation
portion of deformation (3.8.13(3.8.13)) under stress (3.2.29(3.2.29)) that is not annulled by removal of
stress (3.2.29(3.2.29))
[SOURCE: Reference [1ISRM], 67]
3.2.16
keelformed overbreak
characteristic shape of overbreak caused by high, anisotropic rock (3.1.5(3.1.5) )stress (3.2.29(3.2.29))
Note 1 to entry: See Reference [4[4].].
3.2.17
Kirsch's equation
equation, which may be used for evaluating the tangential stresses (3.2.29(3.2.29)) around tunnels and
other underground openings
Note 1 to entry: See Reference [4[4].].
3.2.18
k-value
ratio between horizontal and vertical stresses (3.2.29(3.2.29)) within the rock mass (3.5.25)
Note 1 to entry: See Reference [4[4].].
3.2.19
Mohr’s envelope
envelope of a sequence of Mohr’s circles representing stress (3.2.29(3.2.29)) conditions at failure
(3.6.15(3.6.15)) for a given material
[SOURCE: Reference [1ISRM], 12]
3.2.19.1
angle of internal friction
angle of shear resistance
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ISO/FDIS 22932-3:2023(E)
angle, ϕ, (degrees) between the axis of normal stress (3.2.20(3.2.20)) and the tangent to the Mohr’s
envelope (3.2.19()3.2.19) at a point representing a given failure (3.6.15(3.6.15)-)-stress (3.2.29(3.2.29))
condition for solid material
[SOURCE: Reference [1ISRM], 2]
3.2.20
normal stress
stress (3.2.29(3.2.29)) in a rock (3.1.5(3.1.5)) perpendicular to the shear stress (3.2.27(3.2.27))
[SOURCE: IS 11358:1987 (Reaffirmed 2005)),, 2.203, modified — The phrase "(normal)” was removed of
the definition]
3.2.21
primary state of stress
state of stress (3.2.29(3.2.29)) in a geological formation before it is disturbed by an opening
Note 1 to entry: Adapted from Reference [1[SOURCE: ISRM adapted]
1.1.1
], 46.
3.2.22
primitive stress
virgin rock stress
ground which is in a state of equilibrium before excavation of a tunnel or any underground opening
Note 1 to entry: At this stage, the stresses (3.2.29(3.2.29)) at any point within the ground are termed as “primitive”,
“primary” or “pre-excavation” stresses (3.2.29(3.2.29).).
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.234, modified — Note 1 to entry was originally part of
the definition.]
3.2.23
plasticity
property of a material to continue to deform indefinitely while sustaining a constant stress
(3.2.29(3.2.29))
[SOURCE: Reference [1ISRM], 94]
3.2.24
relaxation
rate of reduction of stress (3.2.29(3.2.29)) in a material due to creep (3.8.10(3.8.10))
Note 1 to entry: An alternate term is stress (3.2.29(3.2.29)) relaxation.
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.240, modified — Note 1 to entry was originally part of
the definition.]
3.2.25
residual stress
stress (3.2.29(3.2.29)) remaining in a solid under zero external stress (3.2.29(3.2.29)) after some
process that causes the dimensions of the various parts of the solid to be incompatible under zero stress
(3.2.29(3.2.29))
EXAMPLE 1 Deformation (3.8.13(3.8.13)) under the action of external stress (3.2.29(3.2.29)) when some parts
of the body suffer permanent strain (3.3.7(3.3.7).).
EXAMPLE 2 Heating or cooling of a body in which the thermal expansion coefficient is not uniform throughout
the body.
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ISO/FDIS 22932-3:2023(E)
[SOURCE: Reference [1ISRM], 49, modified — NotesEXAMPLES 1 and 2 to entry were originally part of
the definition.]
3.2.26
secondary state of stress
resulting state of stress (3.2.29(3.2.29)) in the rock (3.1.5(3.1.5)) around an opening
[SOURCE: Reference [1ISRM], 47, adapted]
3.2.27
shear stress
stress (3.2.29(3.2.29)) directed parallel to the surface element across which it acts
[SOURCE: Reference [1ISRM], 51]
3.2.28
stability
condition of a structure or a mass of material when it is able to support the applied stress (3.2.29(3.2.29))
for a long time without suffering any significant deformation (3.8.13(3.8.13)) or movement that is not
reversed by the release of stress (3.2.29)
[SOURCE: Reference [1ISRM], 15]
3.2.29
stress
force acting across a given surface element, divided by the area of the element as follows:
𝐹𝐹
𝑣𝑣v
σ=
𝐴𝐴
𝐹𝐹 𝐹𝐹
ℎ h
τ=
𝐴𝐴 𝐴𝐴
where
σ is the normal stress;
τ is the shear stress;
Fv is the vertical force;
Fh is the horizontal force;
A is the area of element.
where
 σ is the normal stress (3.2.20);
 τ is the shear stress (3.2.27);
 Fv is the vertical force;
 Fh is the horizontal force;
 A is the area of element.
[SOURCE: Reference [1ISRM], 66]
3.2.30
stress concentration factor
ratio of tangential stress (3.2.29(3.2.29)) at a particular point along the periphery and the initial stress
(3.2.29) before excavation at that point
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ISO/FDIS 22932-3:2023(E)
Note 1 to entry: Stress (3.2.29) concentration takes place when a cavity is excavated in a rock mass (3.5.25(3.5.25).).
Note 2 to entry: The higher the stress (3.2.29) concentration factor, the greater are the chances of failure
(3.6.15(3.6.15)) of the rock mass (3.5.25) or rock burst (3.8.30(3.8.30).).
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.311, modified — Notes 1 and 2 to entry were originally
part of the definition.]
3.2.31
stress ellipsoid
representation of the state of stress (3.2.29(3.2.29)) in the form of an ellipsoid whose semi-axes are
proportional to the magnitudes of the principal stresses (3.2.29) and lie in the principal directions
Note 1 to entry: The coordinates of a point P on this ellipse are proportional to the magnitudes of the respective
components of the stress (3.2.29) across the plane normal to the direction OP, where O is the centercentre of the
ellipsoid.
[SOURCE: Reference [1ISRM], 5, modified — Notes 2Note 1 to entry was originally part of the definition.]
3.2.32
tensile stress
normal stress (3.2.20(3.2.20)) tending to lengthen the body in the direction in which it acts
[SOURCE: Reference [1ISRM], 52]
3.2.33
thermal stress
internal stress (3.2.29(3.2.29),), caused in part by uneven heating
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.327]
3.2.34
triaxial compression
compression caused by the application of normal stresses (3.2.20(3.2.20)) in three perpendicular
directions
[SOURCE: Reference [1ISRM], 21]
3.2.35
triaxial state of stress
state of stress (3.2.29(3.2.29)) in which none of the three principal stresses (3.2.29) is zero
[SOURCE: Reference [1ISRM], 24]
3.2.36
uniaxial compression
unconfined compression
compression caused by the application of normal stress (3.2.20(3.2.20)) in a single direction
[SOURCE: Reference [1ISRM], 19]
3.2.37
uniaxial state of stress
state of stress (3.2.29(3.2.29)) in which two of the three principal stresses (3.2.29) are zero
[SOURCE: Reference [1ISRM], 22]
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ISO/FDIS 22932-3:2023(E)
3.2.38
yield stress
stress (3.2.29(3.2.29)) beyond which the induced deformation (3.8.13(3.8.13)) is not fully annulled after
complete distressing
[SOURCE: Reference [1ISRM], 68]
3.3 Strain
3.3.1
brittleness
material condition characterised by reduced ability to carry load as the strain (3.3.11(3.3.11)) increases
Note 1 to entry: See Reference [4[4].].
3.3.2
contraction
linear strain (3.3.11(3.3.11)) associated with a decrease in length
[SOURCE: Reference [1ISRM], 25]
3.3.3
ductility
condition in which material can sustain permanent deformation (3.8.13(3.8.13)) without losing its ability
to resist load, or on the other hand for a known or particular stress (3.2.29(3.2.29)) state (existing or
imposed) to which a material can sustain plastic deformation (3.8.26(3.8.26)) without breaking
(3.6.7(3.6.7)) or rupture (3.6.30(3.6.30))
Note 1 to entry: Elongation and reduction of area are common indices of ductility.
3.3.4
elastic strain energy
potential energy stored in a strained solid and equal to the work done in deforming the solid from its
unstrained state less any energy dissipated by inelastic deformation (3.2.15(3.2.15))
[SOURCE: Reference [1ISRM], 7]
3.3.5
extension
linear strain (3.3.11(3.3.11)) associated with an increase in length
[SOURCE: Reference [1ISRM], 30]
3.3.6
normal strain
change in length per unit of length in a given direction
[SOURCE: Reference [1ISRM], 35]
3.3.7
permanent strain
strain (3.3.11(3.3.11)) remaining in a solid state with respect to its initial condition after the application
and removal of stress (3.2.29(3.2.29)) greater than the yield stress (3.2.38()3.2.38)
Note 1 to entry: Commonly also called “residual strain” (3.3.8(3.3.8).).
[SOURCE: Reference [1[SOURCE: ISRM adapted]
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ISO/FDIS 22932-3:2023(E)
1.1.2
], 38, modified — "solid" has been replaced by "solid state".]
3.3.8
residual strain
strain (3.3.11(3.3.11)) in a solid state associated with a state of residual stress (3.2.25(3.2.25))
[SOURCE: Reference [1[SOURCE: ISRM adapted]
1.1.3
], 37, modified — "solid" has been replaced by "solid state".]
3.3.9
shear strain
change in shape, expressed by the relative change of the right angles at the corner of what was in the
undeformed state an infinitesimally small rectangle or cube
[SOURCE: Reference [1ISRM], 36]
3.3.10
simple shear
shear strain (3.3.9(3.3.9)) in which displacements (3.8.17(3.8.17)) all lie in one direction and are
proportional to the normal distances of the displaced points from a given reference plane
Note 1 to entry: The dilatation (3.8.15(3.8.15)) is zero.
[SOURCE: Reference [1ISRM], 34, modified — Note 1 to entry was originally part of the definition.]
3.3.11
strain
relative elongation or shortening of a material as result of loading
Note 1 to entry: See Reference [4[4].].
3.3.12
strain ellipsoid
representation of the strain (3.3.11(3.3.11)) in the form of an ellipsoid into which a sphere of unit radius
deforms and whose axes are the principal axes of strain (3.3.11)
[SOURCE: Reference [1ISRM], 6]
3.3.13
strain energy release rate
rate of strain (3.3.11(3.3.11)) energy released per unit area of the excavated surface in the underground
minor tunnel openings
Note 1 to entry: If the strain (3.3.11) energy release rate is more than a limiting value, rock burst (3.8.30(3.8.30)) is
likely to occur.
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.306, modified — Note 1 to entry was originally part of
the definition.]
3.3.14
strain hardening
material that is loaded beyond the yield point within the inelastic domain above the yield point
Not Note 1 to entry: Its state of matter is shown by continuous rise of the stress (3.2.29(3.2.29)-)-strain
(3.3.11(3.3.11)) curve.
[SOURCE:Note 2 to entry: Adapted from IS 11358:1987 (Reaffirmed 2005) adapted], 2.307.
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ISO/FDIS 22932-3:2023(E)
3.3.15
strain softening
during uniaxial or triaxial testing of rocks (3.1.5(3.1.5),), it is generally observed that strength
(3.9.31(3.9.32)) decreases after certain strain (3.3.11(3.3.11))
Note 1 to entry: This is known as strain (3.3.11) softening.
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.308, modified — Note 1 to entry was originally part of
the definition.]]
3.3.16
viscoelasticity
property of materials that strain (3.3.11(3.3.11)) under stress (3.2.29(3.2.29)) partly elastically and
partly viscously, that is, whose strain (3.3.11) is partly dependent on time and magnitude of stress
(3.2.29)
[SOURCE: Reference [1ISRM], 95]
3.4 Both stress and strain
1.1.4
axial 3.4.1
Young's modulus (E)
modulus of elasticity
axial Young's modulus
E
ratio of the axial stress (3.2.29(3.2.29)) change to the axial strain (3.3.11(3.3.11)) produced by the stress
(3.2.29) change for a cylindrical specimen tested in uniaxial compression (3.2.36(3.2.36))
Note 1 to entry: It may be calculated using any of the following methods.
a) a) Tangential Young's modulus, E — This is the tangential Young's modulus at a stress (3.2.29) level
T
which is some fixed percentage of the ultimate strength (3.9.31(3.9.32)) and is generally 50 % of the
ultimate uniaxial compressive strength (3.9.10(3.9.10).).
b) b) Average Young's modulus, E — The average Young's modulus is defined a^as the average slope
ar
of more or less straight portion of the axial stress (3.2.29)--strain (3.3.11) curve.
c) c) Secant Young's modulus, E — The secant Young's modulus is usually measured from zero stress
s
(3.2.29) to some fixed percentage of the ultimate strength (3.9.32),, generally 50 %.
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.19, modified — NotesNote 1 to entry was originally part
of the definition and "modulus of elasticity" and "Young's modulus" were added as equivalent terms.]
3.4.2
deviator of stress
deviator of strain
stress (3.2.29(3.2.29)/)/strain (3.3.11(3.3.11)) tensor obtained by subtracting the mean of the normal
stress (3.2.20(3.2.20)/)/strain (3.3.11) components of a stress (3.2.29)//strain (3.3.11) tensor from
each normal stress (3.2.20)//strain (3.3.11) component
[SOURCE: Reference [1ISRM], 4]
3.4.3
deformation modulus
E
c
in repeated loading-unloading tests, the ratio of stress (3.2.29(3.2.29),), σ to the total strain
(3.3.11(3.3.11) ), in repeated loading-unloading tests, as follows:
10 © ISO 2023 – All rights reserved

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ISO/FDIS 22932-3:2023(E)
𝜎𝜎 𝜎𝜎
𝐸𝐸 = =
c
∈ ∈ + ∈
total el ir
𝜎𝜎 𝜎𝜎
where𝐸𝐸 = =
𝐶𝐶 Deleted Cells
Є Є + Є
𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡 𝑒𝑒𝑡𝑡 𝑖𝑖𝑖𝑖
 E is the deformation modulus;
C
 σ is the normal stress;
 Є is the elastic strain;
el
 Є is the irreversible strain.
ir
where
EC is the deformation modulus;
σ is the normal stress;
Є is the elastic strain;
el
Є is the irreversible strain.Note 1 to entry: This modulus is thus based on the total measured strains
ir
(3.3.11),, that is, elastic plus inelastic (irreversible or plastic) strains (3.3.11),, Є and Є , respectively.
el ir
Note 2 to entry: Total strain (3.3.11) = Єel + Єir.
[SOURCE: IS 11358:1987 (Reaffirmed 2005),, 2.86, modified — Notes 1 and 2 to entry were originally
part of the definition.]
3.4.4
modulus ratio
ratio between the Young's modulus (3.4.1(3.4.1)) and the uniaxial compressive strength (3.9.10(3.9.10))
Note 1 to entry: The higher the value of the modulus ratio, the more brittle (3.8.4(3.8.4)) is the rock (3.1.5(3.1.5).).
Note 2 to entry: The rock material (3.1.6(3.1.6)) is classified as high, medium and low modulus ratio for modulus
ratios of > 500, 500-200 and < 200 respectively.
[SOURCE: IS 11358:1987 (Reaffirmed 2005), 2.194]
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