ASTM D4612-2016 Standard Test Method for Calculating Thermal Diffusivity of Rock and Soil《测定岩土热扩散系数的标准试验方法》.pdf

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1、Designation: D4612 16Standard Test Method forCalculating Thermal Diffusivity of Rock and Soil1This standard is issued under the fixed designation D4612; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n

2、umber 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 involves calculation of the thermaldiffusivity from measured values of the mass density, thermalconductivity, and spec

3、ific heat at constant pressure. It isapplicable for any materials where these data can be deter-mined. The temperature range covered by this test method is293 to 573 K. This test method is closely linked to the overalltest procedure used in obtaining the primary data on density,specific heat, and th

4、ermal conductivity. It cannot be used as a“stand alone” test method because the thermal diffusivityvalues calculated by this test method are dependent on thenature of the primary data base. The test method furnishesgeneral guidelines to calculate the thermal diffusivity butcannot be considered to be

5、 all-inclusive to capture issuesrelated to the density, specific heat, and thermal conductivityNOTE 1The diffusivity, as determined by this test method, is intendedto be a volume average value, with the averaging volume being 2105m3(20 cm3). This requirement necessitates the use of specimens withvol

6、umes greater than the minimum averaging volume and precludes use offlash methods of measuring thermal diffusivity, such as the laser pulsetechnique.1.2 The values stated in SI units are to be regarded as thestandard. No other units of measurements are included in thisstandard.1.3 This test method is

7、 intended to apply to isotropicsamples; that is, samples in which the thermal transportproperties do not depend on the direction of heat flow. If thethermal conductivity depends on the direction of heat flow,then the diffusivity derived by this test method must beassociated with the same direction a

8、s that utilized in theconductivity measurement.1.4 The thermal conductivity, specific heat, and mass den-sity measurements must be made with specimens that are asnear identical in composition and water content as possible.1.5 The generally inhomogeneous nature of geologic forma-tions precludes the u

9、nique specification of a thermal diffusivitycharacterizing an entire rock formation or soil layer. Geologicmedia are highly variable in character, and it is impossible tospecify a test method for diffusivity determination that will besuitable for all possible cases. Some of the most importantlimitat

10、ions arise from the following factors:1.5.1 Variable MineralogyIf the mineralogy of the forma-tion under study is highly variable over distances on the sameorder as the size of the sample from which the conductivity,specific heat, and density specimens are cut, then the calculateddiffusivity for a g

11、iven set of specimens will be dependent onthe precise locations from which these specimens were ob-tained.1.5.2 Variable PorosityThe thermal properties of porousrock or soil are highly dependent on the amount and nature ofthe porosity. A spatially varying porosity introduces problemsof a nature simi

12、lar to those encountered with a spatially varyingcomposition. In addition, the character of the porosity maypreclude complete dehydration by oven drying.1.6 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.6.1 The pr

13、ocedure 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 variation, purpose forobtaining

14、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 significant digits used in analytical

15、methods 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 applica-bility of regulatory limitatio

16、ns prior to use.1This test metis under the jurisdiction of ASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved May 1, 2016. Published May 2016. Originallyapproved in 1986. Last previous edition approved in 2008 as D461

17、2 08. DOI:10.1520/D4612-16.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12. Referenced Documents2.1 ASTM Standards:2C177 Test Method for Steady-State Heat Flux Measure

18、-ments and Thermal Transmission Properties by Means ofthe Guarded-Hot-Plate ApparatusC518 Test Method for Steady-State Thermal TransmissionProperties by Means of the Heat Flow Meter ApparatusC642 Test Method for Density, Absorption, and Voids inHardened ConcreteD653 Terminology Relating to Soil, Roc

19、k, and ContainedFluidsD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4611 Test Method for Specif

20、ic Heat of Rock and SoilD4753 Guide for Evaluating, Selecting, and Specifying Bal-ances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD5334 Test Method for Determination of Thermal Conduc-tivity of Soil and Soft Rock by Thermal Needle ProbeProcedureD6026 Practice for Us

21、ing Significant Digits in GeotechnicalDataE145 Specification for Gravity-Convection and Forced-Ventilation Ovens3. Terminology3.1 Definitions:3.1.1 For definitions of common technical terms used in thisstandard, refer to Terminology D653.3.2 Symbols:3.2.1 mass density (kg/m3).3.2.2 instantaneous spe

22、cific heatcp(J/kgK).3.2.3 thermal conductivityk (W/mK).3.2.4 thermal diffusivity (m2/s).3.2.5 enthalpyh.4. Summary of Test Method4.1 The thermal diffusivity is determined from the equationin 9.3. The data for k and cpmust be available over thetemperature range of interest. For density, , a single me

23、asure-ment at room temperature may be used because the density isapproximately constant over the 293 to 573 K temperaturerange covered by this test method.4.2 The measurements of k, , and cpare to be performedusing the test methods in Section 8.5. Significance and Use5.1 The thermal diffusivity is a

24、 parameter that arises in thesolution of transient heat conduction problems. It generallycharacterizes the rate at which a heat pulse will diffuse througha solid material.5.2 The number of parameters required for solution of atransient heat conduction problem depends on both the geom-etry and impose

25、d boundary conditions. In a few special cases,only the thermal diffusivity of the material is required. In mostcases, separate values of k, , and cpare required in addition to. This test method provides a consistent set of parameters fornumerical or analytical heat conduction calculations related to

26、heat transport through rocks.5.3 In order to use this test method for determination of thethermal diffusivity, the parameters (k, , cp) must be deter-mined under as near identical specimen conditions as possible.5.4 The diffusivity determined by this test method can onlybe used to analyze heat trans

27、port in rock under thermalconditions identical to those existing for the k, , and cpmeasurements.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 facilities used. Agencies that meet thecrit

28、eria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection/etc. Users of this standard arecautioned that compliance with Practice D3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D3740provides a mean

29、s of evaluating some of those factors.6. Apparatus6.1 Analytical BalanceA class GP5 balance meeting therequirements of Specification D4753 for a balance of 1-greadability.6.2 Drying OvenVented, thermostatically-controlled,preferably of the forced-draft type, meeting the requirements ofSpecification

30、E145 and capable of maintaining a uniformtemperature of 110 6 5C throughout the drying chamber.6.3 Vernier caliper, with an accuracy of 60.025 mm.6.4 Waterproof Flexible ContainerA waterproof, flexiblecontainer suitable for encapsulating soil specimens for deter-mining dimensions by immersion.6.5 Co

31、ntainer, suitable for immersing the specimen andsuitable wire for suspending the specimen in water.7. Specimen7.1 Intact Soil Specimens:7.1.1 Thin-Walled Tube or Drive SpecimensCut a 200 630 mm long section of a sampling tube containing an intact soilspecimen. The tube section shall have a minimum d

32、iameter of50 mm.7.1.2 Determine and record the mass of the specimen in asampling tube or brass ring to the nearest 0.1 g.7.1.3 Measure and record the length and diameter of thespecimen to 0.025 mm. Take a minimum of three lengthmeasurements 120 apart and at least three diameter measure-ments at the

33、quarter points of the height. Determine the averagelength and diameter of the specimen.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 the standards Document Summar

34、y page onthe ASTM website.D4612 1627.2 Reconstituted Soil Specimens:7.2.1 Compact the specimen to the desired dry density andgravimetric water content in a thin-walled metal or plastic tubeusing an appropriate compaction technique.7.3 Rock Specimens:7.3.1 Determine and record the mass of the specime

35、n to thenearest 0.1 g and follow the procedure given in 7.1.3 todetermine the specimen diameter and length.8. Procedure8.1 General:8.1.1 Obtain the data for k, , and cpas a function oftemperature using the appropriateASTM standard test methodswith the required levels of accuracy associated with the

36、giventest methods for each parameter, as qualified below. If possible,make measurements using specimens obtained from the samegeneral location in the sample in order to ensure that thespecimens are as near identical in composition and morphologyas possible.8.1.2 To minimize water content variation a

37、mongspecimens, dry specimens at 378 K following the procedures inTest Method D2216, until the percent mass loss is constant to60.5 %.8.2 Qualifications to Other Test Methods:8.2.1 Calculate the specimen total density in one of the twofollowing ways:8.2.1.1 Using the mass of the specimen, ms, measure

38、d on ananalytical balance to the nearest 0.1 g and the volume of thespecimens, Vsto the nearest 0.000001 m3by measurement ofsample dimensions using a Vernier caliper or by water dis-placement (immersion). If the volume is measured byimmersion, the specimen must be encapsulated in a waterproofflexibl

39、e container of negligible volume compared to the speci-men volume. The diameter and height of the test specimen fordetermination of total density shall be at least ten times thediameter of the largest mineral grain. The minimum specimendiameter and height of approximately 47 mm satisfy thiscriterion

40、 in the majority of cases. When cores of diameter andheight smaller than the specified minimum must be testedbecause of the unavailability of larger samples, suitable nota-tion of this fact shall be made in the report. Calculate thespecimen total density (kg/m3), as follows, 5 ms/Vs(1)where:ms= spec

41、imen mass (kg), andVs= specimen volume (m3).Also estimate the accuracy of the determination from theaccuracies associated with the msand Vsmeasurements.8.2.1.2 Measure the specimen bulk specific gravity usingTest Method C642 to the accuracy prescribed in the standard.In situations where the measurem

42、ent is to be made at tempera-tures near or above the boiling point of water, a suitable oilworking fluid may be substituted for water in this procedure.Calculate the total density, , by multiplying the bulk specificgravity by the density of the working fluid at the immersiontemperature. Estimate the

43、 accuracy of the determination fromthe accuracies associated with the bulk specific gravity and theworking fluid measurements.8.2.2 Measure the specimen specific heat using Test MethodD4611 to the prescribed accuracy.8.2.3 Measure the specimen thermal conductivity using TestMethod D5334,Test Method

44、C518, orTest Method C177 to theprescribed accuracy.9. Calculations9.1 GeneralThe following method of calculation is rec-ommended for deriving the temperature dependent diffusivity,(T), from data from k, , and cp.NOTE 3The recommended data analysis technique is not intended topreclude the use of othe

45、r methods of data analysis which may be moresuitable in certain cases. It does provide a method by which a consistentset of temperature dependent parameters may be derived from the primarydata base, and also a method by which the uncertainties in each parametermay be estimated. The results of the ca

46、lculations for the temperaturedependent parameters will be in a form which is useful for most thermalanalysis computer programs.9.2 Description of the MethodThe parameter data for anassociated set of specimens will usually be in the form of tablesgiving the measured parameter value versus the measur

47、ementtemperature. Each parameter shall be fit to an equation of thefollowing form:T! 5(n5oNcnT 2 To!n(2)where: = parameter (k, ,or,cp),To= 293 K,T = temperature (K), andN = maximum power used in the fit.9.2.1 The fit shall be performed using ordinary least squarestechniques.3The value of N shall be

48、as small as possible,consistent with obtaining a reasonable fit to the data. The resultof this fit will be a set of coefficients, (cn), and the estimatedstandard error in the parameter, given by the following equa-tion:sH(i51MTi! 2iTi!#2J1/2(3)where:M = number of temperatures at which is measured, a

49、ndi= measured value of the parameter at temperature Ti.NOTE 4In the case of density, a measurement is usually available onlyat room temperature, To. In this situation, take (T)=(To), correspondingto co= (To), cn= 0 for n 0. The associated error, s, is the estimatederror for the single measurement.9.3 Calculate the diffusivity from the curve fit relationdetermined in 9.2 as follows:T! 5 kT!/T!cpT!#or T! 5 kT!/To!cpT!#9.4 Fit (T) to an equation of the form of Eq 2, and calculatesfrom (Eq 3).3Beck, J. V., and A