ASTM D4535-2013e1 Standard Test Methods for Measurement of Thermal Expansion of Rock Using Dilatometer《用膨胀计测量岩石的热膨胀的标准试验方法》.pdf

1、Designation: D4535 131Standard Test Methods forMeasurement of Thermal Expansion of Rock UsingDilatometer1This standard is issued under the fixed designation D4535; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re

2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial corrections were made throughout in February 2014.1. Scope1.1 These test methods cover the laboratory measurement ofthe on

3、e-dimensional linear thermal expansion of rocks using adilatometer.1.2 The methods are applicable between temperatures of25C to 300C. Both bench top and confined measurementtechniques are presented. Method A is used for unconfined orbench top measurements and Method B is used for confinedconditions.

4、 Rocks of varying moisture content can be tested.1.3 For satisfactory results in conformance with these testmethods, the principles governing the size, construction, anduse of the apparatus described in these test methods should befollowed. If the results are to be reported as having beenobtained by

5、 either test method, then the pertinent requirementsprescribed by that test method shall be met.1.4 These test methods do not establish details of construc-tion and procedures to cover all test situations that might offerdifficulties to a person without technical knowledge concerningthe theory of he

6、at flow, temperature measurement, and generaltesting practices. Standardization of these test methods doesnot reduce the need for such technical knowledge.1.5 UnitsThe values stated in SI units are to be regardedas the standard.The values given in parentheses are mathemati-cal conversions to inch-po

7、und units that are provided forinformation only and are not considered standard. Reporting oftest results in units other than SI shall not be regarded asnonconformance with this test method.1.6 All observed and calculated values shall conform to theguidelines for significant digits and rounding esta

8、blished inPractice D6026.1.6.1 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 ma

9、terial variation, 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 conside

10、r significant digits used in analyticalmethods for engineering design.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 safety and health practices and determine the

11、 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 Water(Moisture) Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for

12、 AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD6026 Practice for Using Significant Digits in GeotechnicalDataE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Characteristic of aLot or Proce

13、ssE83 Practice for Verification and Classification of Exten-someter SystemsE228 Test Method for Linear Thermal Expansion of SolidMaterials With a Push-Rod Dilatometer3. Terminology3.1 Definitions:1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and are the direct r

14、esponsibility of Subcommittee D18.12 on RockMechanics.Current edition approved Nov. 1, 2013. Published December 2013. Originallyapproved in 1985. Last previous edition approved in 2004 as D4535 08. DOI:10.1520/D4535-13E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac

15、t ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.1 For definitions of c

16、ommon technical terms in thisstandard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 specimen thermal strain, tD, nchange in length,(L2 L1), divided by the original length, L0, of the specimenwhen the specimen is subjected to heat.3.2.1.1 DiscussionSpecimen therm

17、al strain is also equalto the corrected thermal expansion, t, divided by the originalspecimen length.3.2.2 mean coeffcient of linear expansion, m,na value,often expressed in parts per million per degree; obtained bydividing the linear thermal strain, (L2 L1)/L0), by the changein temperature (T2 T1).

18、3.2.2.1 DiscussionThe sign convention used for mis asfollows: mwill be a positive value indicating an increase inthe length of the rock specimen upon heating (T2 T1) and mwill be a negative value indicating a decrease or contraction ofthe rock specimen.4. Summary of Test Methods4.1 The application o

19、f heat to a rock causes it to expand.This expansion divided by the original length of the rockspecimen is the thermal strain from which coefficients ofexpansion can be calculated. This standard covers two methodsfor measuring rock expansion. The primary difference betweenthe two methods is in the ty

20、pe of dilatometer used.4.1.1 Test Method A is used when making unconfined orbench top measurements. The method and apparatus aresimilar to that described in Test Method E228. The rockspecimens thermal displacement is measured using a dilatom-eter as shown in Fig. 1. The specimen displacement ismeasu

21、red by a transducer located outside the heated area of thespecimen; therefore, apparent strain due to apparatus expan-sion and contraction is minimized.4.1.2 Test Method B is most suited for the measurement ofrock thermal strain under confined conditions and employs adilatometric device which is loc

22、ated inside the heated zone, asshown in Fig. 2. Test Method B is amenable to confinedthermal strain determinations; however, confined tests may bemost appropriate when:4.1.2.1 Pore pressure must be imposed in the pore space tomaintain the liquid phase of water through the desired tem-perature range.

23、4.1.2.2 The thermal strain of the rock is sensitive to confin-ing stress.4.1.2.3 The specimen is fragile or friable, or both, andcannot be machined into the shapes required for Test MethodA.4.2 In both test methods, specimen expansion is measuredcontinuously as temperature is gradually increased or

24、allowedto stabilize at discrete temperature points.5. Significance and Use5.1 Information concerning the thermal expansion charac-teristics of rocks is important in the design of any undergroundexcavation where the surrounding rock may be heated. Ther-mal strain causes thermal stresses which ultimat

25、ely affectexcavation stability. Examples of applications where rockthermal strain is important include: nuclear waste repositories,underground power stations, compressed air energy storagefacilities, and geothermal energy facilities.5.2 The coefficient of thermal expansion, , of rock isknown to vary

26、 as the temperature changes. These methodsprovide continuous thermal strain values as a function oftemperature, and therefore provide information on how thecoefficient of thermal expansion changes with temperature.5.3 Rocks are also often anisotropic, thus displaying differ-ent thermal strains depen

27、ding on the orientation of strainmeasurement. These methods allow for measuring strain in onedirection only. If anisotropy is expected, specimens withdifferent orientations shall be prepared and tested.NOTE 1The quality of the result produced by this standard isdependent on the competence of the per

28、sonnel performing it, and thesuitability of the equipment and facilities 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 assure reliab

29、le results. Reliableresults depend on many factors; Practice D3740 provides a means ofevaluating some of those factors.6. Interferences6.1 Care should be exercised in the interpretation of thermalstrain data of rocks with significant moisture content. Undercertain temperature and pressure conditions

30、, steam may beproduced in the pore space. Steam may cause errors because ofmicrocrack production or changes in the pore pressure. Thephase change from water to steam in the pore space can resultin several phenomena which complicate data analysis, asfollows:FIG. 1 Apparatus Commonly Used to Perform B

31、ench Top (TestMethod A) Thermal Expansion MeasurementsD4535 13126.1.1 Evolved steam may change the pore pressure and thusthe effective stress in the rock, resulting in anomalous strainreadings.6.1.2 Losing all the moisture may dehydrate clays in thepore space and thus change expansion characteristic

32、s, espe-cially in layered rocks6.1.3 Good judgment should be used when deciding how tomake the thermal expansion measurement so that it accuratelyrepresents the conditions in the field.7. Apparatus7.1 Dilatometer:7.1.1 Test Method AThe dilatometer used for bench mea-surements may be of the tube or r

33、od type, as shown in Fig. 1.Those components of the dilatometer exposed to elevatedtemperatures should be fabricated of materials with coefficientsof linear expansion that are as small as practicable.7.1.2 Test Method BThe entire dilatometer is exposed toelevated temperature; therefore, transducers,

34、 rods, and othercomponents should be fabricated of materials with low thermalexpansions. For example, fused silica, and super invar. Whenthe apparatus is tested with a quartz calibration specimen, theapparatus strain should be less than 20 % of the anticipatedrock strain (refer to Fig. 2).7.2 Extens

35、ometerExtensometers measure length change.In principle, any accurate length measuring device with goodlong-term stability may be used; including dial gauges, linearvariable differential transducers, or capacitive transducers.Whichever device is selected, it must have sufficient resolutionto measure

36、0.01 % specimen strain (Refer to Practice E83).7.2.1 Devices used in Test Method B must be fabricated ofmaterials that allow direct exposure of the device to theanticipated temperature. Also, transducer bodies should bevented for operation in a pressure environment. At least twotransducers are used,

37、 as shown in Fig. 2, and their outputsaveraged.7.3 FurnaceThe furnace shall be large enough to containthe specimen and apparatus and maintain uniform temperaturealong the axis of the specimen with variations no greater thanFIG. 2 Apparatus Commonly Used to Perform Confined (Test Method B) Thermal Ex

38、pansion MeasurementsD4535 131361C. The mean specimen temperature shall be controlledwithin 61C. The use of a programmable temperature control-ler that can slowly increase or decrease specimen temperaturesat rates at least as low as 0.1C/min is recommended.7.4 Temperature Measuring Instruments Thermo

39、couplesor platinum resistant thermometers are recommended. Theexact type will depend on the temperature range of interest. Ingeneral, the temperature should be measured to within 60.5Cwith a resolution of at least 60.2C. Make measurements atthree locations on the axis of the specimen, one near each

40、endand one at the specimen midpoint.7.5 Specimen Size Measurement DevicesDevices used tomeasure the length and diameter of the specimen shall becapable of measuring the desired dimension to within 0.1 % ofits actual length.8. Sampling8.1 The number and types of rock cores tested depend partlyon the

41、intended application of the test results. For example, aninitial mechanical characterization of a site might requireseveral samples from a variety of formations, while a detailedthermo-mechanical investigation of a particular location mayrequire many rock tests from a single formation. The finaltest

42、ing program will depend on the technical judgment and theexperience of project personnel.8.2 Statistical RequirementsThe number of samples andspecimens tested shall be sufficient to provide an adequatestatistical basis for evaluation of the results. Rock types that arehighly variable will require mo

43、re tests than relatively uniformrocks in order to evaluate the results with equal certainty.8.2.1 The number of samples and specimens required toobtain a specific level of statistically valid results may bedetermined using Test Method E122. However, it may not beeconomically possible to achieve spec

44、ific confidence levels andprofessional judgment may be required.8.2.2 DocumentationSince the thermal expansion of mostrock is anisotropic, it is important that the field orientation ofeach sample is recorded. Note the orientation of each sampleon the sample and carry suitable markings through each c

45、uttinguntil the final specimen is ready for testing. These markingsshould indicate compass direction and up/down directions, andother orientation with respect to geologic structures.8.3 Moisture Condition of SamplesThe moisture condi-tion of the rock can influence the measured thermal expansion.The

46、samples shall be preserved to prevent moisture change8.4 AnisotropyThe thermal expansion coefficient of manyrocks is different along various axes of the rock; therefore, inorder to assess the degree of anisotropy, the thermal expansionmust be measured in several directions.9. Preparation of Test Spe

47、cimens9.1 Take the samples and machine them into the propergeometry as discussed in 9.2.9.1.1 Do not degrade the rock during machining. Preventmechanical and fracture damage to the rock fabric by appro-priately slow machining processes and the use of propercoolant. Select coolant fluids based upon c

48、hemical compatibil-ity with the rock; for example, tap water may be adequate forgranite, whereas a saturated brine or mineral oil may be bestfor salt.9.2 Dimension and GeometryIn general, the proper geom-etry of a specimen is a right circular cylinder. The specificrecommended dimensions for Test Met

49、hod A are given in TestMethod E228. For Test Method B, the specimen should be aright circular cylinder with a length to diameter ratio of 2 to 1.For both methods the minimum dimension should be 10 timesthe largest grain size. Measure and record the length anddiameter of the specimen to 0.001 mm. Take a minimum ofthree length measurements 120 apart and at least threediameter measurements at the quarter points of the height.Determine the average length and diameter of the specimen.9.3 Moisture Condition of SpecimensTest the specimensin a