ASTM D3967-2016 Standard Test Method for Splitting Tensile Strength of Intact Rock Core Specimens《完整岩石芯样的劈裂抗拉强度的标准试验方法》.pdf

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1、Designation: D3967 08D3967 16Standard Test Method forSplitting Tensile Strength of Intact Rock Core Specimens1This standard is issued under the fixed designation D3967; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la

2、st 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 This test method covers testing apparatus, specimen preparation, and testing procedures for determining the splitting t

3、ensilestrength of rock by diametral line compression of a disk.disk shape specimens.NOTE 1The tensile strength of rock determined by tests other than the straight pull test is designated as the “indirect” tensile strength and, specifically,the value obtained in Section 9 of this test is termed the “

4、splitting” tensile strength.1.2 UnitsThe values stated in SI units are to be regarded as the standard. The values given in parentheses are mathematicalconversions and to inch-pound units, which are provided for information only.only and are not considered standard. Reporting oftest results in units

5、other than SI shall not be regarded as nonconformance with this test method.1.3 All dimension and force measurements, and stress calculations observed and calculated values shall conform to theguidelines for significant digits and rounding established in Practice D6026.1.3.1 The procedures used to s

6、pecify how data are collected/recorded or calculated, in this standard are regarded as the industrystandard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do notconsider material variation, purpose for obtaining the data, specia

7、l purpose studies, or any considerations for the users objectives;and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations.It is beyond the scope of this standard to consider significant digits used in analysis methods for engin

8、eering design1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. R

9、eferenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and Contained FluidsD2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil an

10、d Rock as Used inEngineering Design and ConstructionD6026 Practice for Using Significant Digits in Geotechnical DataE4 Practices for Force Verification of Testing MachinesE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE2586 Practice for Calculating a

11、nd Using Basic Statistics3. Terminology3.1 Refer to Terminology D653 for specific definitions.Definitions:3.1.1 For common definitions of terms in this standard, refer to Terminology D653.4. Summary of Test Method4.1 Samples are selected from rock cores or cored from platen samples for testing as de

12、scribed. A section of rock core sampleis cut perpendicular to the core axis to produce disk shape specimens until the required number of specimens are obtained. Eachspecimen is then marked to indicate the desired orientation of the applied loading on the specimen by drawing a diametral line1 This te

13、st 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, 2008Nov. 1, 2016. Published July 2008November 2016. Originally approved in 1981. Last previous edition approved in 200

14、52008 asD3967 05.D3967 08. DOI: 10.1520/D3967-08.10.1520/D3967-16.2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume information, refer to the standards Document Summary page on the ASTM w

15、ebsite.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. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult pr

16、ior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19

17、428-2959. United States1on each end surface on the specimen. Each specimen is positioned inside the testing machine in such way that diametrical line iscoincidental with the loading axis of the testing machine either curved or flat platens. Each specimen is then tested by applyinga continuously incr

18、easing compressive load until it fails within 1 to 10 minutes of the start of loading.5. Significance and Use5.1 By definition the tensile strength is obtained by the direct uniaxial tensile test. ButHowever, the direct tensile test is difficultand expensive for routine application. The splitting te

19、nsile test appears to offer a desirable alternative, because it is much simplerand inexpensive. Furthermore, engineers involved in rock mechanics design usually deal with complicated stress fields, includingvarious combinations of compressive and tensile stress fields. Under such conditions, the ten

20、sile strength should be obtained withthe presence of compressive stresses to be representative of the field conditions. The splitting tensile strength test is one of thesimplest tests in which such stress fields occur. Since it is widely used in practice, a uniform test method is needed for data to

21、becomparable. A uniform test is also needed to ensure that the disk specimens break diametrally due to tensile pulling along theloading diameter.5.2 The splitting tensile strength test is one of the simplest tests in which such stress fields occur.Also, by testing across differentdiametrical directi

22、ons, possible variations in tensile strength for anisotropic rocks can be determined. Since it is widely used inpractice, a uniform test method is needed for data to be comparable. A uniform test is also needed to make sure that the diskspecimens break diametrically due to tensile stresses perpendic

23、ular to the loading diameter.NOTE 2Notwithstanding the statements on precision and bias contained in this test method; the precision of this test method The quality of the resultsproduced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equip

24、ment and facilities used.Agenciesthat meet the criteria of Practice D3740 are generally considered capable of competent and objective testing. testing/sampling/inspection/etc. Users ofthis standard are cautioned that compliance with Practice D3740Reliable testing depends does not in itself assure re

25、liable results. Reliable results dependon many factors; Practice D3740 provides a means of evaluating some of thesethose factors.6. Apparatus6.1 Loading Device, Device to apply and measure axial load on the specimen, A device of sufficient capacity to apply andmeasure the load at a rate conforming t

26、o the requirements in 8.3. It shall be verified at suitable time intervals in accordance withPractices E4 and shall comply with the requirements prescribed therein.6.1.1 Bearing PlatensThe loading device shall be equipped with two opposing steel bearing platens having a Rockwellhardness of not less

27、than 58 HRC through which loading is transmitted. The bearing faces shall not depart from a plane by morethan 0.0125 mm (0.0005 in.) when the platens are new and shall be maintained within a permissible variation of 0.025 mm. Thebearing platens diameter shall be at least as great as the specimens th

28、ickness (see Note 3).6.1.2 Spherical SeatingOne of the bearing surfaces on the loading device should be spherically seated and the other one aplain rigid platen. The diameter of the spherical seat shall be at least as large as the test specimen, but the diameter of the spericalseat shall not exceed

29、from twice the diameter of specimen. Center of the sphere in the spherical seat coincides with the center ofloaded side of the specimen. The spherical seat shall be lubricated to assure its free movement. The movable part of the platen shallbe held closely in the spherical seat, but the design shall

30、 be such that the bearing face can be rotated and tilted through small anglesin any direction. If the spherical seats diameter exceeds twice the diameter of the test specimen, then the spherical seat shall beplaced in the locked position with the faces of the bearing platens meeting the requirements

31、 of 6.1.1.6.1.3 Rigid SeatingIf a spherical seat is not used, then the faces of the loading device bearing platens shall be parallel to0.0005 mm/mm of the platen diameter. This criterion shall be met when the platens are in the loading device and separatedapproximately by diameter of the test specim

32、en.NOTE 3False platens, due to the contact with abrasive rocks, these platens tend to roughen after a number of specimens have been tested, and henceneed to be surfaced from time to time.6.2 Bearing SurfacesFalse, Flat or Curved Bearing PlatensThe testing machine During testing, the specimen can be

33、placedin direct contact with the loading device bearing platens or false platens with bearing faces conforming to the requirements of thisstandard, may be used (see Fig. 1shall be equipped with two steel bearing blocks having a Rockwell hardness of not less than 58HRC (see for false flat platens). T

34、hese shall be oil hardened to more than 58 HRC, and surface ground. With contact by abrasiverocks, these platens Note 3).tend to roughen after a number of specimens have been tested, and hence need to be re-surfaced fromtime to time.NOTE 3False platens, with bearing faces conforming to the requireme

35、nts of this standard, may be used. These shall be oil hardened to more than 58HRC, and surface ground. With abrasive rocks these platens tend to roughen after a number of specimens have been tested, and hence need to be surfacedfrom time to time.6.2.1 False Flat Bearing BlocksBearingDuring testing t

36、he specimen can be placed in direct contact with the machinebearing plates (or false platens, if used) (see The bearing faces of false flat bearing platens Fig. 1). The bearing faces shall notdepart from a plane by more than 0.0125 mm (0.0005 in.) when the platens are new and shall be maintained wit

37、hin a permissiblevariation of 0.025 mm. The bearing blockplatens diameter shall be at least as great as the specimen thickness.D3967 1626.2.2 Curved Supplementary Bearing Blocks, PlatensThese may be used to reduce the contact stresses. stresses on the testspecimen. The radius of curvature of the sup

38、plementary bearing platesplatens shall be so designed that their arc of contact withthe specimen will in no case exceed 15 or that the width of contact is less than D/6, where D is the diameter of the specimen.NOTE 4Since the equation used in 9.1 for splitting tensile strength is derived based on a

39、line load, the applied load shallshould be confined to a verynarrow strip if the splitting tensile strength test is to be valid. But a line load creates extremely high contact stresses which cause premature cracking.A wider contact strip can reduce the problems significantly. InvestigationsStudies s

40、how that an arc of contact smaller than 15 causes no more than 2 %of error in principal tensile stress while reducing the incidence of premature cracking greatly.5.2.3 Spherical SeatingOne of the bearing surfaces should be spherically seated and the other a plain rigid block.The diameterof the spher

41、ical seat shall be at least as large as that of the test specimen, but shall not exceed twice the diameter of the testspecimen. The center of the sphere in the spherical seat shall coincide with the center of the loaded side of the specimen. Thespherical seat shall be lubricated to assure free movem

42、ent. The movable portion of the platen shall be held closely in the sphericalseat, but the design shall be such that the bearing face can be rotated and tilted through small angles in any direction.5.2.4 Rigid SeatingIf a spherical seat is not used, the faces of the bearing blocks shall be parallel

43、to 0.0005 mm/mm of theblock diameter. This criterion shall be met when the blocks are in the loading device and separated by approximately the diameterof the test specimen.6.3 Bearing Strips (optional)0.01 D thick cardboard cushions, where D is the specimenspecimens diameter; or up to 6.4 mm(0.25 in

44、.) thick plywood cushions are recommended to be placed between the machine bearing surfaces (or supplementary bearingsupplementary-bearing plates; if used) and the specimen to reduce high stress concentration.NOTE 5Experience has indicated that test results using the curved supplementary bearing pla

45、tes and bearing strips, as specified in 5.2.26.2.2 and5.36.3, respectively, do not significantly differ from each other, but there may be some consistent difference from the results of tests in which direct contactbetween the specimen and the machine platen is used.6. Sampling6.1 The specimens shall

46、 be selected from the core to obtain the type of rock under consideration. This can be achieved by visualobservations to select a range of specimens based on mineral constituents, grain sizes and shape, partings, and defects such as poresand fissures.FIG. 1 One Proposed Testing Setup for Splitting T

47、ensile StrengthD3967 1637. Test Specimens Sampling, Test Specimens, and Test Units7.1 The samples shall be selected by visual observation to include a range of specimens based on rock type, mineralconstituents, grain sizes and shape, partings, and defects such as pores and fissures.7.2 DimensionsTes

48、t Specimens: The test specimen shall be a circular disk with a thickness-to-diameter ratio (t/D) between 0.2and 0.75. The diameter of the specimen shall be at least 10 times greater than the largest mineral grain constituent. A diameter of54 mm (1-1516 in.) (NX core) will generally satisfy this crit

49、erion.7.2.1 DimensionsThe test specimen shall be a circular disk with a thickness-to-diameter ratio (t/D) between 0.2 and 0.75. Thediameter of the specimen shall be at least 10 times greater than the largest mineral grain constituent. A diameter of 54 mm (NXcore) will generally satisfy this criterion.NOTE 6When cores smaller than the specified minimum must be tested because of the unavailability of material, notation of the fact shall be madein the test report.NOTE 7If the specimen shows apparent anisotropic features such as bedding or schistosit