1、Designation: D4535 132Standard 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 2014.2NOTEEditorially updated units of measurement statement in April 2018.1.
3、 Scope1.1 These test methods cover the laboratory measurement ofthe one-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
4、 orbench top measurements and Method B is used for confinedconditions. 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 b
5、efollowed. If the results are to be reported as having beenobtained by 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 offerdifficult
6、ies to a person without technical knowledge concerningthe theory of heat flow, temperature measurement, and generaltesting practices. Standardization of these test methods doesnot reduce the need for such technical knowledge.1.5 The values stated in SI units are to be regarded asstandard. The values
7、 given in parentheses after SI units areprovided for information only and are not considered standard.Reporting of test results in units other than SI shall not beregarded as nonconformance with this test method.1.6 All observed and calculated values shall conform to theguidelines for significant di
8、gits and rounding established 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 u
9、sed do not consider material 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 th
10、is standard to consider 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, health, and env
11、ironmental practices and deter-mine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Stand
12、ards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soi
13、l and Rock by MassD3740 Practice for Minimum Requirements for 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
14、 Precision, the Average for a Characteristic of aLot or Process1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and are the direct responsibility of Subcommittee D18.12 on RockMechanics.Current edition approved Nov. 1, 2013. Published December 2013. Originallyappro
15、ved in 1985. Last previous edition approved in 2004 as D4535 08. DOI:10.1520/D4535-13E02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume information, refer to the standards Document Summa
16、ry page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles
17、for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1E83 Practice for Verification and Classification of Exten-someter SystemsE228 Test Method for Linear Thermal Expansion of SolidMaterials With
18、a Push-Rod Dilatometer3. Terminology3.1 Definitions:3.1.1 For definitions of common 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 s
19、pecimenwhen the specimen is subjected to heat.3.2.1.1 DiscussionSpecimen thermal 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 bydividin
20、g the linear thermal strain, (L2 L1)/L0), by the changein temperature (T2 T1).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 c
21、ontraction ofthe rock specimen.4. Summary of Test Methods4.1 The application of 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 measur
22、ing rock expansion. The primary difference betweenthe two methods is in the type 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 measu
23、red using a dilatom-eter as shown in Fig. 1. The specimen displacement ismeasured 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
24、strain under confined conditions and employs adilatometric device which is located 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 spac
25、e tomaintain the liquid phase of water through the desired tem-perature range.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, specim
26、en expansion is measuredcontinuously as temperature is gradually increased or 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 surroun
27、ding rock may be heated. Ther-mal strain causes thermal stresses which ultimately affectexcavation stability. Examples of applications where rockthermal strain is important include: nuclear waste repositories,underground power stations, compressed air energy storagefacilities, and geothermal energy
28、facilities.5.2 The coefficient of thermal expansion, , of rock isknown to vary 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 Rock
29、s are also often anisotropic, thus displaying differ-ent thermal strains depending 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
30、 the result produced by this standard isdependent on the competence of the personnel 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
31、 cautioned that compliancewith Practice D3740 does not in itself assure reliable results. Reliableresults depend on many factors; Practice D3740 provides a means ofFIG. 1 Apparatus Commonly Used to Perform Bench Top (TestMethod A) Thermal Expansion MeasurementsD4535 1322evaluating some of those fact
32、ors.6. Interferences6.1 Care should be exercised in the interpretation of thermalstrain data of rocks with significant moisture content. Undercertain temperature and pressure conditions, steam may beproduced in the pore space. Steam may cause errors because ofmicrocrack production or changes in the
33、pore pressure. Thephase change from water to steam in the pore space can resultin several phenomena which complicate data analysis, asfollows:6.1.1 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
34、 may dehydrate clays in thepore space and thus change expansion characteristics, 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 Tes
35、t Method AThe dilatometer used for bench mea-surements may be of the tube or rod 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
36、 entire dilatometer is exposed toelevated temperature; therefore, transducers, 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 shoul
37、d be less than 20 % of the anticipatedrock strain (refer to Fig. 2).7.2 ExtensometerExtensometers 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 transduce
38、rs.FIG. 2 Apparatus Commonly Used to Perform Confined (Test Method B) Thermal Expansion MeasurementsD4535 1323Whichever device is selected, it must have sufficient resolutionto measure 0.01 % specimen strain (Refer to Practice E83).7.2.1 Devices used in Test Method B must be fabricated ofmaterials t
39、hat 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, as shown in Fig. 2, and their outputsaveraged.7.3 FurnaceThe furnace shall be large enough to containthe specimen
40、and apparatus and maintain uniform temperaturealong the axis of the specimen with variations no greater than61C. 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
41、as low as 0.1C/min is recommended.7.4 Temperature Measuring Instruments Thermocouplesor 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. M
42、ake measurements atthree locations on the axis of the specimen, one near each 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
43、.8. Sampling8.1 The number and types of rock cores tested depend partlyon the 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 particu
44、lar location mayrequire many rock tests from a single formation. The finaltesting 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
45、 evaluation of the results. Rock types that arehighly variable will require more 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
46、 Test Method E122. However, it may not beeconomically possible to achieve specific 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 orie
47、ntation of each sampleon the sample and carry suitable markings through each cuttinguntil 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 moi
48、sture condi-tion of the rock can influence the measured thermal expansion.The 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 ther
49、mal expansionmust be measured in several directions.9. Preparation of Test Specimens9.1 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 chemical 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 a
