ASTM D7012-10
(Test Method)Standard Test Method for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures
Standard Test Method for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures
SIGNIFICANCE AND USE
The parameters obtained from Methods A and B are in terms of undrained total stress (as already mentioned in 1.1). 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.
Uniaxial compressive strength (Method C) 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. The triaxial compression test (Method A) 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.
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, inhomogeneities, weakness planes, and other factors. Therefore, laboratory values for intact specimens must be employed with proper judgment in engineering applications.
Note 2—Notwithstanding the statements on precision and bias contained in this test method; the measures of precision of these test methods are dependent on the competence of the personnel performing them, and on 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 test method are cautioned that compliance with Practice D3740 does not in itself assure reliable testing. Reliable testing depends on many factors; Practice D3740 provides a means for evaluating some of those factors.
SCOPE
1.1 These test methods cover the determination of the strength of intact rock core specimens in uniaxial and triaxial compression. The tests provide data in determining the strength of rock, namely: the uniaxial strength, shear strengths at different pressures and different elevated temperatures, angle of internal friction, (angle of shearing resistance), and cohesion intercept. The test methods 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. It should be observed that these methods make no provision for pore pressure measurements and specimens are undrained (platens are not vented). Thus the strength values determined are in terms of total stress, that is, 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.
1.2 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.
1.2.1 Method A: Triaxial Compressive Strength of Undrained Rock Core Specimens Without Pore Pressure Measurements.
1.2.2 Method B: Elastic Moduli of Undrained Rock Core Specimens in Triaxial Compression Without Pore Pressure Measurements.
1.2.3 Method C: Uniaxial Compressive Strength of Intact Rock Core Specimens.
1.2.4 Method D: Elastic Moduli of Intact Rock Core Specimens in Uniaxial Compression.
1.2.5 Option A: Elevated Temperatures.
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Designation: D7012 − 10
StandardTest Method 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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.2.3 Method C: Uniaxial Compressive Strength of Intact
Rock Core Specimens.
1.1 These test methods cover the determination of the
1.2.4 Method D: Elastic Moduli of Intact Rock Core Speci-
strength of intact rock core specimens in uniaxial and triaxial
mens in Uniaxial Compression.
compression.Thetestsprovidedataindeterminingthestrength
1.2.5 Option A: Elevated Temperatures.
of rock, namely: the uniaxial strength, shear strengths at
different pressures and different elevated temperatures, angle
1.3 For an isotropic material in Test Methods B and D, the
ofinternalfriction,(angleofshearingresistance),andcohesion
relation between the shear and bulk moduli and Young’s
intercept. The test methods specify the apparatus,
modulus and Poisson’s ratio are:
instrumentation, and procedures for determining the stress-
E
axial strain and the stress-lateral strain curves, as well as G 5 (1)
2 11υ
~ !
Young’s modulus, E, and Poisson’s ratio, υ. It should be
E
observed that these methods make no provision for pore
K 5 (2)
3~1 22υ!
pressure measurements and specimens are undrained (platens
are not vented). Thus the strength values determined are in
where:
terms of total stress, that is, are not corrected for pore
G = shear modulus,
pressures. These test methods do not include the procedures
K = bulk modulus,
necessary to obtain a stress-strain curve beyond the ultimate
E = Young’s modulus, and
strength.
υ = Poisson’s ratio.
1.2 This standard replaces and combines the following
1.3.1 The engineering applicability of these equations de-
Standard Test Methods: D2664 Triaxial Compressive Strength
creaseswithincreasinganisotropyoftherock.Itisdesirableto
of Undrained Rock Core Specimens Without Pore Pressure
conduct tests in the plane of foliation, cleavage or bedding and
Measurements;D5407ElasticModuliofUndrainedRockCore
at right angles to it to determine the degree of anisotropy. It is
Specimens in Triaxial Compression Without Pore Pressure
notedthatequationsdevelopedforisotropicmaterialsmaygive
Measurements; D2938 Unconfined Compressive Strength of
only approximate calculated results if the difference in elastic
Intact Rock Core Specimens; and D3148 Elastic Moduli of
moduli in two orthogonal directions is greater than 10% for a
Intact Rock Core Specimens in Uniaxial Compression. The
given stress level.
original four standards are now referred to as Methods in this
NOTE 1—Elastic moduli measured by sonic methods (Test Method
standard.
D2845) may often be employed as a preliminary measure of anisotropy.
1.2.1 Method A: Triaxial Compressive Strength of
1.4 Test Methods B and D for determining the elastic
Undrained Rock Core Specimens Without Pore Pressure Mea-
constants do not apply to rocks that undergo significant
surements.
inelastic strains during the test, such as potash and salt. The
1.2.2 Method B: Elastic Moduli of Undrained Rock Core
elastic moduli for such rocks should be determined from
Specimens in Triaxial Compression Without Pore Pressure
unload-reload cycles, that are not covered by this test method.
Measurements.
1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
standard.
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.
1.6 All observed and calculated values shall conform to the
Current edition approved Jan. 15, 2010. Published March 2010. Originally
e1
guidelines for significant digits and rounding established in
approved in 2004. Last previous edition approved in 2007 as D7012–07 . DOI:
10.1520/D7012-10. Practice D6026.
*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
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D7012 − 10
1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
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D7012 − 10
responsibility of the user of this standard to establish appro- Deformationandstrengthofrockareknowntobefunctionsof
priate safety and health practices and determine the applica- confiningpressure.Thetriaxialcompressiontest
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:D7012–07 Designation: D7012 – 10
Standard Test Method 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
´ NOTE—Adjunct number in Footnote 3 was changed editorially in July 2009
1. Scope*
1.1This1.1 These test methods covers the determination of the strength of intact rock core specimens in uniaxial compression
and confinedtriaxial compression. The tests provide data in determining the strength of rock, namely: the uniaxial strength, shear
strengths at varyingdifferent pressures and varying different elevated temperatures, angle of internal friction, (angle of shearing
resistance), and cohesion intercept. The test method specifiesmethods 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, y.It
should be observed that this method makesthese methods make no provision for pore pressure measurements and specimens are
undrained (platens are not vented). Thus the strength values determined are in terms of total stress, that is, are not corrected for
pore pressures.ThisThese test method doesmethods do not include the procedures necessary to obtain a stress-strain curve beyond
the ultimate strength.
1.1.1This1.2 This standard replaces and combines the following Standard Test Methods for: Methods: D2664 Triaxial
Compressive Strength of Undrained Rock Core Specimens Without Pore Pressure Measurements; D5407 Elastic Moduli of
Undrained Rock Core Specimens inTriaxial CompressionWithout Pore Pressure Measurements; D2938 Unconfined Compressive
Strength of Intact Rock Core Specimens; and D3148 Elastic Moduli of Intact Rock Core Specimens in Uniaxial Compression.
1.1.2TheThe original four standards are now referred to as Methods in this standard as follows: Method A — standard.
1.2.1 Method A: Triaxial Compressive Strength of Undrained Rock Core Specimens Without Pore Pressure Measurements;.
1.2.2 Method B —: Elastic Moduli of Undrained Rock Core Specimens in Triaxial Compression Without Pore Pressure
Measurements; Method C — Unconfined Measurements.
1.2.3 Method C: Uniaxial Compressive Strength of Intact Rock Core Specimens; Method D — Specimens.
1.2.4 Method D: Elastic Moduli of Intact Rock Core Specimens in Uniaxial Compression; and Option A — Compression.
1.2.5 Option A: Elevated Temperatures.
1.2For1.3 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:
(1) G 5 E211y
where:
G = shear modulus,
K = bulk modulus,
E = Young’s modulus, and
y = Poisson’s ratio.
1.2.1The1.3.1 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 in two orthogonal directions is greater than 10 % for a given stress level.
NOTE 1—Elastic moduli measured by sonic methods (Test Method D2845) may often be employed as preliminary measures of anisotropy.
1.3This test method given for determining the elastic constants does not apply to rocks that undergo significant inelastic strains
1
This test method is 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 July 1, 2007. Published July 2007. Originally approved in 2004. Last previous edition approved in 2004 as D7012–04
e1
Current edition approved Jan. 15, 2010. Published March 2010. Originally approved in 2004. Last previous edition approved in 2007 as D7012–07 . DOI:
10.1520/D7012-07E01. DOI: 10.1520/D7012-10.
*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 – 10
during the test,
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