1、Designation: D7012 14Standard Test Methods 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
2、adoption 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. Scope1.1 These four test methods cover the determination of thestrength of in
3、tact rock core specimens in uniaxial and triaxialcompression. MethodsAand B determine the triaxial compres-sive strength at different pressures and Methods C and Ddetermine the unconfined, uniaxial strength.1.2 Methods A and B can be used to determine the angle ofinternal friction, angle of shearing
4、 resistance, and cohesionintercept.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 asYoungs modulus, E, and Poissons ratio, . These methodsmake no provision for pore pressure measurements
5、and speci-mens are undrained (platens are not vented). Thus, the strengthvalues determined are in terms of total stress and are notcorrected for pore pressures. These test methods do not includethe procedures necessary to obtain a stress-strain curve beyondthe ultimate strength.1.4 OptionAallows for
6、 testing at different temperatures andcan be applied to any of the test methods, if requested.1.5 This standard replaces and combines the followingStandard Test Methods: D2664 Triaxial Compressive Strengthof Undrained Rock Core Specimens Without Pore PressureMeasurements; D5407 Elastic Moduli of Und
7、rained Rock CoreSpecimens in Triaxial Compression Without Pore PressureMeasurements; D2938 Unconfined Compressive Strength 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 thissta
8、ndard.1.5.1 Method A: Triaxial Compressive Strength ofUndrained Rock Core Specimens Without Pore Pressure Mea-surements.1.5.1.1 Method A is used for obtaining strength determina-tions. Strain is not typically measured; therefore a stress-straincurve is not produced.1.5.2 Method B: Elastic Moduli of
9、Undrained Rock CoreSpecimens in Triaxial Compression Without Pore PressureMeasurements.1.5.3 Method C: Uniaxial Compressive Strength of IntactRock Core Specimens.1.5.3.1 Method C is used for obtaining strength determina-tions. Strain is not typically measured; therefore a stress-straincurve is not p
10、roduced.1.5.4 Method D: Elastic Moduli of Intact Rock Core Speci-mens in Uniaxial Compression.1.5.5 Option A: Temperature VariationApplies to any ofthe methods and allows for testing at temperatures above orbelow room temperature.1.6 For an isotropic material in Test Methods B and D, therelation bet
11、ween the shear and bulk moduli and Youngsmodulus and Poissons ratio are:G 5E211!(1)K 5E31 2 2!(2)where:G = shear modulus,K = bulk modulus,E = Youngs modulus, and = Poissons ratio.1.6.1 The engineering applicability of these equations de-creases with increasing anisotropy of the rock. It is desirable
12、 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 approximate calculated results if the difference in elasticmoduli in two orthogonal directions is g
13、reater 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.1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and is the direct responsibility of Subcommittee
14、 D18.12 on RockMechanics.Current edition approved May 1, 2014. Published June 2014. Originallyapproved in 2004. Last previous edition approved in 2013 as D7012 13. DOI:10.1520/D7012-14.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Driv
15、e, PO Box C700, West Conshohocken, PA 19428-2959. United States11.7 Test Methods B and D for determining 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-rel
16、oad cycles that are not covered by these test meth-ods.1.8 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.9 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inP
17、ractice D6026.1.9.1 The procedures used to specify how data are collected/recorded or calculated, in this standard are regarded as theindustry standard. In addition, they are representative of thesignificant digits that generally should be retained. The proce-dures used do not consider material vari
18、ation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives; and it is common practice toincrease or reduce significant digits of reported data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significa
19、nt digits used in analyticalmethods for engineering design.1.10 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 safety and health practices and determine the applica-b
20、ility 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 Water(Moisture) Content of Soil and Rock by MassD2845 Test Method for Laboratory Determination of Pul
21、seVelocities 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 as Cylindrical TestSpecimens and Verifying Conformance t
22、o Dimensionaland Shape TolerancesD6026 Practice for Using Significant Digits in GeotechnicalDataE4 Practices for Force Verification of Testing MachinesE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or Process2.2 ASTM Adjunct:3
23、Triaxial Compression Chamber Drawings (3)3. Terminology3.1 Definitions:3.1.1 For definitions of common technical terms in thisstandard, refer to Terminology D653.4. Summary of Test Method4.1 A rock core specimen is cut to length and the ends aremachined flat. The specimen is placed in a loading fram
24、e andif necessary, placed in a loading chamber and subjected toconfining pressure. For a specimen tested at a differenttemperature, the test specimen is heated or cooled to thedesired test temperature prior to the start of the test. The axialload on the specimen is then increased and measured contin
25、u-ously. Deformation measurements are not obtained for Meth-ods A and C, and are measured as a function of load until peakload and failure are obtained for Methods B and D.5. Significance and Use5.1 The parameters obtained from Methods A and B are interms of undrained total stress. However, there ar
26、e some caseswhere either the rock type or the loading condition of theproblem under consideration will require the effective stress ordrained parameters be determined.5.2 Method C, uniaxial compressive strength of rock is usedin many design formulas and is sometimes used as an indexproperty to selec
27、t the appropriate excavation technique. Defor-mation and strength of rock are known to be functions ofconfining pressure. Method A, triaxial compression test, iscommonly used to simulate the stress conditions under whichmost underground rock masses exist. The elastic constants(Methods B and D) are u
28、sed to calculate the stress anddeformation in rock structures.5.3 The deformation and strength properties of rock coresmeasured in the laboratory usually do not accurately reflectlarge-scale in situ properties because the latter are stronglyinfluenced by joints, faults, inhomogeneity, weakness plane
29、s,and other factors. Therefore, laboratory values for intactspecimens must be employed with proper judgment in engi-neering applications.NOTE 2The quality of the result produced by this standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment and fac
30、ilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing. Users of this standard are cautioned that compliancewith Practice D3740 does not in itself ensure reliable results. Reliableresults depend on many factors; Practice D374
31、0 provides a means forevaluating some of those factors.6. Apparatus6.1 Compression Apparatus:6.1.1 Methods A to D:2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to th
32、e 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 operate ata confining fluid pressure of 68.9 MPa are available from ASTM InternationalHeadquarters. Order
33、Adjunct No. ADJD7012. Original adjunct produced in 1982.D7012 1426.1.1.1 Loading DeviceThe loading device shall be ofsufficient capacity to apply load at a rate conforming to therequirements specified in 9.4.1. It shall be verified at suitabletime intervals in accordance with the procedures given in
34、Practices 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 confining compression a
35、pparatus, calibrations to determine theseal friction need to be made to make sure the loads measured meet theaccuracy specified in Practices E4.6.2 Confining System:36.2.1 Methods A and B:6.2.1.1 Confining Apparatus4The confining pressure ap-paratus shall consist of a chamber in which the test speci
36、menmay be subjected to a constant lateral fluid pressure and therequired axial load. The apparatus shall have safety valves,suitable entry ports for filling the chamber, and associatedhoses, gages, and valves as needed.6.2.1.2 Flexible MembraneThis membrane encloses therock specimen and extends over
37、 the platens to prevent penetra-tion by the confining fluid. A sleeve of natural or syntheticrubber or plastic is satisfactory for room temperature tests;however, metal or high-temperature rubber (viton) jackets areusually necessary for elevated temperature tests. The mem-brane shall be inert relati
38、ve to the confining fluid and shallcover small pores in the specimen without rupturing whenconfining pressure is applied. Plastic or silicone rubber coat-ings may be applied directly to the specimen provided thesematerials do not penetrate and strengthen or weaken thespecimen. Care must be taken to
39、form an effective seal wherethe platen and specimen meet. Membranes formed by coatingsshall be subject to the same performance requirements aselastic sleeve membranes.6.2.1.3 Pressure-Maintaining DeviceA hydraulic pump,pressure intensifier, or other system having sufficient capacityto maintain the d
40、esired lateral pressure to within 61%throughout the test. The confining pressure shall be measuredwith a hydraulic pressure gauge or electronic transducer havingan accuracy of at least 61 % of the confining pressure,including errors due to readout equipment, and a resolution ofat least 0.5 % of the
41、confining pressure.6.2.1.4 Confining-Pressure FluidsHydraulic fluids com-patible with the pressure-maintaining device and flexiblemembranes shall be used. For tests using Option A, the fluidmust remain stable at the temperature and pressure levelsdesignated for the test.6.2.2 Option A:6.2.2.1 Temper
42、ature EnclosureThe temperature enclosureshall be either an internal system that fits inside the loadingapparatus or the confining pressure apparatus, an externalsystem enclosing the entire confining pressure apparatus, or anexternal system encompassing the complete test apparatus. Forhigh or low tem
43、peratures, a system of heaters or coolers,respectively, insulation, and temperature-measuring devicesare normally necessary to maintain the specified temperature.Temperature shall be measured at three locations, with onesensor near the top, one at mid-height, and one near the bottomof the specimen.
44、The “average” specimen temperature, basedon the mid-height sensor, shall be maintained to within 61Cof the specified test temperature. The maximum temperaturedifference between the mid-height sensor and either end sensorshall not exceed 3C.NOTE 4An alternative to measuring the temperature at three l
45、ocationsalong 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 mid-height and each end of the specimen. Thespecimen may originate
46、 from 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 ce
47、nterline temperature atmid-height may be within 61C of the specified 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
48、 testing provided that the output of the temperature feedback sensoror other fixed-location temperature sensor in the triaxial apparatus ismaintained constant within 61C of the specified test temperature. Therelationship between temperature controller set point and steady-statespecimen temperature m
49、ay be 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 resistance 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:(1) PlatensTwo steel platens are used to transmit theaxial load to the ends of the specimen. They shall be m
