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Designation: D7012 – 10

Standard Test Method for

Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures1
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 inparentheses indicates the year of last reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

1. 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 differentpressures 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, y. It should be observed that these methods make no provision forpore 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: D2664Triaxial 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 nowreferred 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 RockCore Specimens in Uniaxial Compression. 1.2.5 Option A: Elevated Temperatures. 1.3 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:
G5 K5 E 2~1 1 y! (1) (2)

E 3~1 2 2y!

where: G = shear modulus, K = bulk modulus, E = Young’s modulus, and y = Poisson’s ratio. 1.3.1 The engineering applicability ofthese 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 a preliminary measure of anisotropy.

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 Jan. 15, 2010. Published March 2010. Originallyapproved in 2004. Last previous edition approved in 2007 as D7012–07 e1. DOI: 10.1520/D7012-10.

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1.4 Test Methods B and D for determining the elastic constants do not apply to rocks that undergo significant inelastic strains during the test, such as potash and salt. The elastic moduli for such rocks should be determined from unload-reload cycles, that are not covered by this test method.

*A...