1、Designation: D7012 10Standard Test Method forCompressive Strength and Elastic Moduli of Intact RockCore Specimens under Varying States of Stress andTemperatures1This standard is issued under the fixed designation D7012; the number immediately following the designation indicates the year oforiginal a
2、doption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover the determination of thestrength of intact
3、rock core specimens in uniaxial and triaxialcompression. The tests provide data in determining the strengthof rock, namely: the uniaxial strength, shear strengths atdifferent pressures and different elevated temperatures, angleof internal friction, (angle of shearing resistance), and cohesioninterce
4、pt. The test methods specify the apparatus, instrumen-tation, and procedures for determining the stress-axial strainand the stress-lateral strain curves, as well asYoungs modulus,E, and Poissons ratio, y. It should be observed that thesemethods make no provision for pore pressure measurementsand spe
5、cimens are undrained (platens are not vented). Thus thestrength values determined are in terms of total stress, that is,are not corrected for pore pressures. These test methods do notinclude the procedures necessary to obtain a stress-strain curvebeyond the ultimate strength.1.2 This standard replac
6、es and combines the followingStandard Test Methods: D2664 Triaxial Compressive Strengthof Undrained Rock Core Specimens Without Pore PressureMeasurements; D5407 Elastic Moduli of Undrained Rock CoreSpecimens in Triaxial Compression Without Pore PressureMeasurements; D2938 Unconfined Compressive Stre
7、ngth ofIntact Rock Core Specimens; and D3148 Elastic Moduli ofIntact Rock Core Specimens in Uniaxial Compression. Theoriginal four standards are now referred to as Methods in thisstandard.1.2.1 Method A: Triaxial Compressive Strength of Und-rained Rock Core Specimens Without Pore Pressure Measure-me
8、nts.1.2.2 Method B: Elastic Moduli of Undrained Rock CoreSpecimens in Triaxial Compression Without Pore PressureMeasurements.1.2.3 Method C: Uniaxial Compressive Strength of IntactRock Core Specimens.1.2.4 Method D: Elastic Moduli of Intact Rock Core Speci-mens in Uniaxial Compression.1.2.5 Option A
9、: Elevated Temperatures.1.3 For an isotropic material in Test Methods B and D, therelation between the shear and bulk moduli and Youngsmodulus and Poissons ratio are:G 5E21 1y!(1)K 5E31 2 2y!(2)where:G = shear modulus,K = bulk modulus,E = Youngs modulus, andy = Poissons ratio.1.3.1 The engineering a
10、pplicability of these equations de-creases with increasing anisotropy of the rock. It is desirable toconduct tests in the plane of foliation, cleavage or bedding andat right angles to it to determine the degree of anisotropy. It isnoted that equations developed for isotropic materials may giveonly a
11、pproximate calculated results if the difference in elasticmoduli in two orthogonal directions is greater than 10 % for agiven stress level.NOTE 1Elastic moduli measured by sonic methods (Test MethodD2845) may often be employed as a preliminary measure of anisotropy.1.4 Test Methods B and D for deter
12、mining the elasticconstants do not apply to rocks that undergo significantinelastic strains during the test, such as potash and salt. Theelastic moduli for such rocks should be determined fromunload-reload cycles, that are not covered by this test method.1This test method is under the jurisdiction o
13、fASTM Committee D18 on Soil andRock 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 D701207e1. DOI:10.1520/D7012-10.1*A Summary of Changes sec
14、tion appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 All observed and
15、calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate s
16、afety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by M
17、assD2845 Test Method for Laboratory Determination of PulseVelocities and Ultrasonic Elastic Constants of RockD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4543 Practices for Preparing Rock Core
18、as CylindricalTest Specimens and Verifying Conformance to Dimen-sional and Shape TolerancesD6026 Practice for Using Significant Digits in GeotechnicalDataE4 Practices for Force Verification of Testing MachinesE122 Practice for Calculating Sample Size to Estimate,With Specified Precision, the Average
19、 for a Characteristicof a Lot or Process2.2 ASTM Adjunct:3Triaxial Compression Chamber Drawings (3)3. Terminology3.1 Refer to Terminology D653 for specific definitions.4. Summary of Test Method4.1 A rock core specimen is cut to length and the ends aremachined flat. The specimen is placed in a loadin
20、g frame andif required, placed in a loading chamber and subjected toconfining pressure. In an elevated temperature test the speci-men is heated to the desired test temperature. Axial load isincreased continuously on the specimen, and deformation ismeasured as a function of load until peak load and f
21、ailure areobtained.5. Significance and Use5.1 The parameters obtained from Methods A and B are interms of undrained total stress (as already mentioned in 1.1).However, there are some cases where either the rock type orthe loading condition of the problem under consideration willrequire the effective
22、 stress or drained parameters be deter-mined.5.2 Uniaxial compressive strength (Method C) of rock isused in many design formulas and is sometimes used as anindex property to select the appropriate excavation technique.Deformation and strength of rock are known to be functions ofconfining pressure. T
23、he triaxial compression test (MethodA) iscommonly used to simulate the stress conditions under whichmost underground rock masses exist. The elastic constants(Methods B and D) are used to calculate the stress anddeformation in rock structures.5.3 The deformation and strength properties of rock coresm
24、easured in the laboratory usually do not accurately reflectlarge-scale in situ properties because the latter are stronglyinfluenced by joints, faults, inhomogeneities, weakness planes,and other factors. Therefore, laboratory values for intactspecimens must be employed with proper judgment in engi-ne
25、ering applications.NOTE 2Notwithstanding the statements on precision and bias con-tained in this test method; the measures of precision of these test methodsare dependent on the competence of the personnel performing them, andon the suitability of the equipment and facilities used. Agencies that mee
26、tthe criteria of Practice D3740 are generally considered capable ofcompetent and objective testing. Users of this test method are cautionedthat compliance with Practice D3740 does not in itself assure reliabletesting. Reliable testing depends on many factors; Practice D3740provides a means for evalu
27、ating some of those factors.6. Apparatus6.1 Compression Apparatus:6.1.1 Methods A to D:6.1.1.1 Loading DeviceThe loading device shall be ofsufficient capacity to apply load at a rate conforming to therequirements specified in 10.4.1. It shall be verified at suitabletime intervals in accordance with
28、the procedures given inPractices E4 and comply with the requirements prescribed inthe method. The loading device may be equipped with adisplacement transducer that can be used to advance theloading ram at a specified rate.NOTE 3For Methods A and B, if the load-measuring device is locatedoutside the
29、confining compression apparatus, calibrations to determine theseal friction need to be made to ensure the accuracy specified in PracticesE4.6.2 Confining System3:6.2.1 Methods A and B:6.2.1.1 Confining Apparatus4The confined pressure appa-ratus shall consist of a chamber in which the test specimen m
30、aybe subjected to a constant lateral fluid pressure and the requiredaxial load. The apparatus shall have safety valves, suitableentry ports for filling the chamber, and associated hoses, gages,and valves as needed.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM C
31、ustomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Assembly and detail drawings of an apparatus that meets these requirementsand which is designed to accommodate 54 mm diameter specimens and operat
32、e ata confining fluid pressure of 68.9 MPa are available from ASTM InternationalHeadquarters. Order Adjunct No. ADJD7012. Original adjunct produced in 1982.4Assembly and detail drawings of an apparatus that meets these requirementsand which is designed to accommodate 21/8-in. (53.975-mm) diameter sp
33、ecimensand operate at a confining fluid pressure of 68.9 Mpa are available from ASTMInternational Headquarters. Order Adjunct No. ADJD7012. Original adjunct pro-duced in 1982.D7012 1026.2.1.2 Flexible MembraneThis membrane encloses therock specimen and extends over the platens to prevent penetra-tio
34、n by the confining fluid. A sleeve of natural or syntheticrubber or plastic is satisfactory for room temperature tests;however, metal or high-temperature rubber (for example,viton) jackets are usually required for elevated temperaturetests. The membrane shall be inert relative to the confiningfluid
35、and shall cover small pores in the specimen withoutrupturing when confining pressure is applied. Plastic or sili-cone rubber coatings may be applied directly to the specimenprovided these materials do not penetrate and strengthen orweaken the specimen. Care must be taken to form an effectiveseal whe
36、re the platen and specimen meet. Membranes formedby coatings shall be subject to the same performance require-ments as elastic sleeve membranes.6.2.1.3 Pressure-Maintaining DeviceA hydraulic pump,pressure intensifier, or other system having sufficient capacityto maintain constant the desired lateral
37、 pressure to within61 % throughout the test. The confining pressure shall bemeasured with a hydraulic pressure gauge or electronic trans-ducer having an accuracy of at least 61 percent of theconfining pressure, including errors due to readout equipment,and a resolution of at least 0.5 % of the confi
38、ning pressure.6.2.1.4 Confining-Pressure FluidsHydraulic fluids com-patible with the pressure-maintaining device and flexiblemembranes shall be used. For elevated temperature tests(option A), the fluid must remain stable at the temperature andpressure levels designated for the test.6.2.2 Option A:6.
39、2.2.1 Elevated-Temperature EnclosureThe elevatedtemperature enclosure shall be either an internal system that fitsinside the loading apparatus or the confining pressure appara-tus, an external system enclosing the entire confining pressureapparatus, or an external system encompassing the completetes
40、t apparatus. For high temperatures, a system of heaters,insulation, and temperature-measuring devices are normallyrequired to maintain the specified temperature. Temperatureshall be measured at three locations, with one sensor near thetop, one at midheight, and one near the bottom of the specimen.Th
41、e “average” specimen temperature, based on the midheightsensor, shall be maintained to within 61C of the required testtemperature. The maximum temperature difference betweenthe midheight sensor and either end sensor shall not exceed3C.NOTE 4An alternative to measuring the temperature at three locati
42、onsalong the specimen during the test is to determine the temperaturedistribution in a specimen that has temperature sensors located in drillholes at a minimum of six positions: along both the centerline andspecimen periphery at midheight and each end of the specimen. Thespecimen may originate from
43、the same batch as the test specimens andconform to the same dimensional tolerances and to the same degree ofintactness. The temperature controller set point may be adjusted to obtainsteady-state temperatures in the specimen that meet the temperaturerequirements at each test temperature (the centerli
44、ne temperature atmidheight may be within 61C of the required test temperature, and allother specimen temperatures may not deviate from this temperature bymore than 3C). The relationship between controller set point andspecimen temperature can be used to determine the specimen temperatureduring testi
45、ng provided that the output of the temperature feedback sensor(or other fixed-location temperature sensor in the triaxial apparatus) ismaintained constant within 61C of the required test temperature. Therelationship between temperature controller set point and steady-statespecimen temperature may be
46、 verified periodically. The specimen is usedsolely to determine the temperature distribution in a specimen in thetriaxial apparatus. It is not to be used to determine compressive strengthor elastic constants.6.2.2.2 Temperature Measuring DeviceSpecial limits-of-error thermocouples or platinum resist
47、ance thermometers(RTDs) having accuracies of at least 61C with a resolution of0.1C shall be used.6.2.3 Bearing Surfaces:6.2.3.1 Methods A to D:6.2.3.1.1 PlatensTwo steel platens are used to transmitthe axial load to the ends of the specimen. They shall be madeof tool-hardened steel to a minimum Rock
48、well Hardness of 58on the “C” scale. One of the platens shall be spherically seatedand the other shall be a plain rigid platen. The bearing facesshall not depart from a plane by more than 0.015 mm when theplatens are new and shall be maintained within a permissiblevariation of 0.025 mm. The diameter
49、 of the spherical seat shallbe at least as large as that of the test specimen, but shall notexceed twice the diameter of the test specimen. The center ofthe sphere in the spherical seat shall coincide with that of thebearing face of the specimen. The spherical seat shall beproperly lubricated to assure free movement. The movableportion of the platen shall be held closely in the spherical seat,but the design shall be such that the bearing face can be rotatedand tilted through small angles in any direction. If a sphericalseat is not used, the bearing surfaces
