ASTM D7012-23
(Test Method)Standard Test Methods for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures
Standard Test Methods for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures
SIGNIFICANCE AND USE
5.1 The parameters obtained from Methods A and B are in terms of undrained total stress. However, there are some cases where either the rock type or the loading condition of the problem under consideration will require the effective stress or drained parameters be determined.
5.2 Method C, uniaxial compressive strength of rock is used in many design formulas and is sometimes used as an index property to select the appropriate excavation technique. Deformation and strength of rock are known to be functions of confining pressure. Method A, triaxial compression test, is commonly used to simulate the stress conditions under which most underground rock masses exist. The elastic constants (Methods B and D) are used to calculate the stress and deformation in rock structures.
5.3 The deformation and strength properties of rock cores measured in the laboratory usually do not accurately reflect large-scale in situ properties because the latter are strongly influenced by joints, faults, inhomogeneity, weakness planes, and other factors. Therefore, laboratory values for intact specimens shall be employed with proper judgment in engineering applications.
Note 2: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable results depend on many factors; Practice D3740 provides a means for evaluating some of those factors.
SCOPE
1.1 These four test methods cover the determination of the strength of intact rock core specimens in uniaxial and triaxial compression. Methods A and B determine the triaxial compressive strength at different pressures and Methods C and D determine the unconfined, uniaxial strength.
1.2 Methods A and B can be used to determine the angle of internal friction, angle of shearing resistance, and cohesion intercept.
1.3 Methods B and D specify the apparatus, instrumentation, and procedures for determining the stress-axial strain and the stress-lateral strain curves, as well as Young's modulus, E, and Poisson's ratio, υ. These methods do not make provisions for pore pressure measurements and specimens are undrained (platens are not vented). Thus, the strength values determined are in terms of total stress and are not corrected for pore pressures. These test methods do not include the procedures necessary to obtain a stress-strain curve beyond the ultimate strength.
1.4 Option A allows for testing at different temperatures and can be applied to any of the test methods, if requested.
1.5 This standard replaces and combines the following Standard Test Methods: D2664 Triaxial Compressive Strength of Undrained Rock Core Specimens Without Pore Pressure Measurements; D5407 Elastic Moduli of Undrained Rock Core Specimens in Triaxial Compression Without Pore Pressure Measurements; D2938 Unconfined Compressive Strength of Intact Rock Core Specimens; and D3148 Elastic Moduli of Intact Rock Core Specimens in Uniaxial Compression. The original four standards are now referred to as Methods in this standard.
1.5.1 Method A—Triaxial Compressive Strength of Undrained Rock Core Specimens Without Pore Pressure Measurements.
1.5.1.1 Method A requires strength determination only. Strain measurements and a stress-strain curve are not required.
1.5.2 Method B—Elastic Moduli of Undrained Rock Core Specimens in Triaxial Compression Without Pore Pressure Measurements.
1.5.3 Method C—Uniaxial Compressive Strength of Intact Rock Core Specimens.
1.5.3.1 Method C requires strength determination only. Strain measurements and a stress-strain curve are not required.
1.5.4 Method D—Elastic Moduli of Intact Rock Core Specimens in Uniax...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7012 − 23
Standard Test Methods for
Compressive Strength and Elastic Moduli of Intact Rock
Core Specimens under Varying States of Stress and
1
Temperatures
This standard is issued under the fixed designation D7012; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.5.1.1 Method A requires strength determination only.
Strain measurements and a stress-strain curve are not required.
1.1 These four test methods cover the determination of the
1.5.2 Method B—Elastic Moduli of Undrained Rock Core
strength of intact rock core specimens in uniaxial and triaxial
Specimens in Triaxial Compression Without Pore Pressure
compression. Methods A and B determine the triaxial compres-
Measurements.
sive strength at different pressures and Methods C and D
1.5.3 Method C—Uniaxial Compressive Strength of Intact
determine the unconfined, uniaxial strength.
Rock Core Specimens.
1.2 Methods A and B can be used to determine the angle of
1.5.3.1 Method C requires strength determination only.
internal friction, angle of shearing resistance, and cohesion
Strain measurements and a stress-strain curve are not required.
intercept.
1.5.4 Method D—Elastic Moduli of Intact Rock Core Speci-
1.3 Methods B and D specify the apparatus,
mens in Uniaxial Compression.
instrumentation, and procedures for determining the stress-
1.5.5 Option A: Temperature Variation—Applies to any of
axial strain and the stress-lateral strain curves, as well as
the methods and allows for testing at temperatures above or
Young’s modulus, E, and Poisson’s ratio, υ. These methods do
below room temperature.
not make provisions for pore pressure measurements and
1.6 For an isotropic material in Test Methods B and D, the
specimens are undrained (platens are not vented). Thus, the
relation between the shear and bulk moduli and Young’s
strength values determined are in terms of total stress and are
modulus and Poisson’s ratio are:
not corrected for pore pressures. These test methods do not
E
include the procedures necessary to obtain a stress-strain curve
G 5 (1)
2~11υ!
beyond the ultimate strength.
E
1.4 Option A allows for testing at different temperatures and
K 5 (2)
3 1 2 2υ
~ !
can be applied to any of the test methods, if requested.
where:
1.5 This standard replaces and combines the following
Standard Test Methods: D2664 Triaxial Compressive Strength
G = shear modulus,
of Undrained Rock Core Specimens Without Pore Pressure K = bulk modulus,
Measurements; D5407 Elastic Moduli of Undrained Rock Core E = Young’s modulus, and
υ = Poisson’s ratio.
Specimens in Triaxial Compression Without Pore Pressure
Measurements; D2938 Unconfined Compressive Strength of
1.6.1 The engineering applicability of these equations de-
Intact Rock Core Specimens; and D3148 Elastic Moduli of
creases with increasing anisotropy of the rock. It is desirable to
Intact Rock Core Specimens in Uniaxial Compression. The
conduct tests in the plane of foliation, cleavage or bedding and
original four standards are now referred to as Methods in this
at right angles to it to determine the degree of anisotropy. It is
standard.
noted that equations developed for isotropic materials may give
1.5.1 Method A—Triaxial Compressive Strength of Und-
only approximate calculated results if the difference in elastic
rained Rock Core Specimens Without Pore Pressure Measure-
moduli in two orthogonal directions is greater than 10 % for a
ments.
given stress level.
1 NOTE 1—Elastic moduli measured by sonic methods (Test Method
These test methods are under the jurisdiction of ASTM Committee D18 on Soil
D2845) may often be employed as a preliminary measure of anisotropy.
and Rock and is the direct responsibility of Subcommittee D18.12 on Rock
Mechanics.
1.7 Test Methods B and D for determining the elastic
Current edition approved June 15, 2023. Published June 2023. Originally
ɛ1
constants do not apply to rocks that undergo significant
approved in 2004. Last previous edition approved in 2014 as D7012 – 14 . DOI:
10.1520/D7012-23. inelastic strains during the test, such as potash and salt. The
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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D7012 − 23
elastic moduli for such rocks should be determined from E122 Practice for Calculating Sample Size to Esti
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: D7012 − 14 D7012 − 23
Standard Test Methods for
Compressive Strength and Elastic Moduli of Intact Rock
Core Specimens under Varying States of Stress and
1
Temperatures
This standard is issued under the fixed designation D7012; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
ε NOTE—Editorially corrected legend for Eq 3 in August 2017.
1. Scope Scope*
1.1 These four test methods cover the determination of the strength of intact rock core specimens in uniaxial and triaxial
compression. Methods A and B determine the triaxial compressive strength at different pressures and Methods C and D determine
the unconfined, uniaxial strength.
1.2 Methods A and B can be used to determine the angle of internal friction, angle of shearing resistance, and cohesion intercept.
1.3 Methods B and D specify the apparatus, instrumentation, and procedures for determining the stress-axial strain and the
stress-lateral strain curves, as well as Young’s modulus, E, and Poisson’s ratio, υ. These methods make no provision do not make
provisions for pore pressure measurements and specimens are undrained (platens are not vented). Thus, the strength values
determined are in terms of total stress and are not corrected for pore pressures. These test methods do not include the procedures
necessary to obtain a stress-strain curve beyond the ultimate strength.
1.4 Option A allows for testing at different temperatures and can be applied to any of the test methods, if requested.
1.5 This standard replaces and combines the following Standard Test Methods: D2664 Triaxial Compressive Strength of
Undrained Rock Core Specimens Without Pore Pressure Measurements; D5407 Elastic Moduli of Undrained Rock Core
Specimens in Triaxial Compression Without Pore Pressure Measurements; D2938 Unconfined Compressive Strength of Intact
Rock Core Specimens; and D3148 Elastic Moduli of Intact Rock Core Specimens in Uniaxial Compression. The original four
standards are now referred to as Methods in this standard.
1.5.1 Method A: A—Triaxial Compressive Strength of Undrained Rock Core Specimens Without Pore Pressure Measurements.
1.5.1.1 Method A is used for obtaining strength determinations. Strain is not typically measured; therefore requires strength
determination only. Strain measurements and a stress-strain curve is not produced.are not required.
1.5.2 Method B: B—Elastic Moduli of Undrained Rock Core Specimens in Triaxial Compression Without Pore Pressure
Measurements.
1
These test methods are under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.
Current edition approved May 1, 2014June 15, 2023. Published June 2014June 2023. Originally approved in 2004. Last previous edition approved in 20132014 as D7012
ɛ1
– 13.14 . DOI: 10.1520/D7012-14E01.10.1520/D7012-23.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D7012 − 23
1.5.3 Method C: C—Uniaxial Compressive Strength of Intact Rock Core Specimens.
1.5.3.1 Method C is used for obtaining strength determinations. Strain is not typically measured; therefore requires strength
determination only. Strain measurements and a stress-strain curve is not produced.are not required.
1.5.4 Method D: D—Elastic Moduli of Intact Rock Core Specimens in Uniaxial Compression.
1.5.5 Option A: Temperature Variation—Applies to any of the methods and allows for testing at temperatures above or below room
temperature.
1.6 For an isotropic material in Test Methods B and D, the relation between the shear and bulk moduli and Young’s modulus and
Poisson’s ratio are:
E
G 5 (1)
2 11υ
~ !
E
K 5 (2)
3~12 2υ!
where:
G = shear modulus,
K = bulk modulus,
E = Young’s modulus, and
υ = Poisson’s ratio.
1.6.1 The engineering applicability of these equations decreases with increasing anisotropy of the rock. It is desirable to conduct
tests in the plane of foliation, cleavage or bedding and at right angles to it to determine the degree of anisotropy. It is noted that
equations developed for isotropic materials may give only approximate calculated results if the difference in elastic moduli
...
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