1、Designation: D 5334 05Standard Test Method forDetermination of Thermal Conductivity of Soil and SoftRock by Thermal Needle Probe Procedure1This standard is issued under the fixed designation D 5334; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method presents a procedure for determiningthe thermal conductivity of soil an
3、d soft rock using a transientheat method. This test method is applicable for both undis-turbed and remolded soil specimens and soft rock specimens.This test method is suitable only for isotropic materials.1.2 This test method is applicable to dry materials over thetemperature range from 20 to 100C.
4、It may be used over alimited range around ambient room temperatures for specimenscontaining moisture.1.3 For satisfactory results in conformance with this testmethod, the principles governing the size, construction, anduse of the apparatus described in this test method should befollowed. If the resu
5、lts are to be reported as having beenobtained by this test method, then all pertinent requirementsprescribed in this test method shall be met.1.4 It is not practicable in a test method of this type to aimto establish details of construction and procedure to cover allcontingencies that might offer di
6、fficulties to a person withouttechnical knowledge concerning the theory of heat flow,temperature measurement, and general testing practices. Stan-dardization of this test method does not reduce the need forsuch technical knowledge. It is recognized also that it would beunwise, because of the standar
7、dization of this test method, toresist in any way the further development of improved or newmethods or procedures by research workers.1.5 The values stated in SI units are to be regarded as thestandard. The inch-pound units given in parentheses are forinformation only.1.6 All measured and calculated
8、 values shall conform to theguidelines for significant digits and rounding established InPractice D 6026.1.7 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
9、 health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock and ContainedFluidsD 2216 Test Method for Laboratory Determination of Water(Moisture) Content of Soil and RockD 3740 Practice
10、for Minimum Requirements for AgenciesEngaged in The testing and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD 4439 Terminology for GeotextilesD 6026 Practice for Using Significant Digits in Geotechni-cal Data3. Terminology3.1 Terminology used within this test method i
11、s in accor-dance with Terminologies D 653 and D 4439 with the additionof the following:3.1.1 heat inputpower consumption of heater wire inwatts per unit length that is assumed to be the equivalent ofheat output per unit length of wire.3.1.2 thermal epoxyany thermally conductive filled epoxymaterial
12、having a value of l 4 W/(mk).3.1.3 thermal greaseany thermally conductivity greasehaving a value of l 4 W/(mk).4. Summary of Test Method4.1 The thermal conductivity is determined by a variation ofthe line source test method using a needle probe having a largelength to diameter ratio to stimulate con
13、ditions for an infinitelylong specimen. The probe consists of a heating element and atemperature measuring element and is inserted into the speci-men. A known current and voltage is applied to the probe andthe temperature rise with time noted over a period of time. The1This test method is under the
14、jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 1992. Last previous edition approved in 2004 as D 5334 00 (2004).2For referenced ASTM stan
15、dards, 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 Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM Inte
16、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.thermal conductivity is obtained from an analysis of theapproximately linear portion of the quasi-steady-statetemperature-time response.5. Significance and Use5.1 The thermal conductivity of both undisturb
17、ed and re-molded soil specimens as well as soft rock specimens is usedto analyze and design systems used, for example, in under-ground transmission lines, oil and gas pipelines, radioactivewaste disposal, and solar thermal storage facilities.NOTE 1Notwithstanding the statements on precision and bias
18、 con-tained in this test method; the precision of this test method is dependenton the competence of the personnel performing it, and the suitability of theequipment and facilities used. Agencies that meet the criteria of PracticeD 3740 are generally considered capable of competent and objectivetesti
19、ng. Users of this test method are cautioned that compliance withPractice D 3740 does not in itself assure reliable testing. Reliable testingdepends on many factors; Practice D 3740 provides a means of evaluatingsome of those factors.6. Apparatus6.1 Thermal Needle ProbeA device that creates a linearh
20、eat source and incorporates a temperature measuring element(thermocouple or thermistor) to measure the variation oftemperature at a point along the line. The construction of asuitable device is described in Annex A1.6.2 Constant Current SourceA device to produce a con-stant current.6.3 Thermal Reado
21、ut UnitA device to produce a digitalreadout of temperature in degrees Celsius to the nearest 0.1K6.4 Voltage-Ohm-Meter (VOM)A device to read voltageand current to the nearest 0.01 V and ampere.6.5 Timer, stopwatch or similar time measuring instrumentcapable of measuring to the nearest 0.1 s for a mi
22、nimum of 15min.6.6 Equipment, capable of drilling a straight vertical holehaving a diameter as close as possible to that of the needle andto a depth at least equal to the length of the needle.7. Specimen Preparation7.1 Undisturbed Soil Specimens:7.1.1 Thin-Walled Tube or Drive SpecimensCut a 200 630
23、-mm (8.0 6 1-in.) long section of a sampling tube containingan undisturbed soil specimen. The tube section should have aminimum diameter of 51 mm (2 in.).7.1.2 Weigh the specimen in a sampling tube or brass rings.7.1.3 Insert the thermal needle probe down the axis of thespecimen by either pushing th
24、e probe into a predrilled hole(dense specimen) to a depth equal to the length of the probe orpushing the probe into the specimen (loose specimen). Careshould be taken to ensure that the thermal probe shaft is fullyembedded in the specimen and not left partially exposed. (SeeNote 2.)NOTE 2To provide
25、better thermal contact between the specimen andthe probe, the probe may be coated with a thin layer of thermal grease. Ifa hole is predrilled for the needle probe, the diameter of the hole shouldbe equal to the diameter of the needle probe to ensure a tight fit. A device,such as a drill press, may b
26、e used to insert the probe to ensure that theprobe is inserted vertically and that no void spaces are formed between thespecimen and the probe.7.2 Remolded Soil Specimens:7.2.1 Compact the specimen to the desired density andwater content (in a thin-walled metal or plastic tube) using anappropriate c
27、ompaction technique. For further guidance on theeffect of the various compaction techniques on thermal con-ductivity, refer to Mitchell et al. (1).3The tube should have aminimum diameter of 51 mm (2 in.) and a length of 200 6 30mm (8.0 6 1 in.).7.2.2 Perform 7.1.2 and 7.1.3.7.3 Soft Rock Specimens:7
28、.3.1 Specimen dimensions shall be no less than those of thecalibration standard (8.3).7.3.2 Insert the thermal needle probe into the specimen bypredrilling a hole to a depth equal to the length of the probe.Care should be taken to ensure that the thermal probe shaft isfully embedded in the specimen
29、and not left partially exposed.(See Note 2.)8. Calibration8.1 The thermal needle probe apparatus should be calibratedbefore its use. Perform calibration by comparing the experi-mental determination of the thermal conductivity of a standardmaterial to its known value.8.2 Conduct the test specified in
30、 Section 9 using a calibra-tion standard as specified in 8.3.8.3 Calibration StandardOne or more materials withknown values of thermal conductivity in the range of thematerials being measured (typically 0.2 l 5 W/mK).Suitable materials include dry Ottawa sand, Pyrex 7740, FusedSilica and Pryoceram 9
31、606 (2). The calibration standard shallbe in the shape of a cylinder. The diameter of the cylinder shallbe at least 40 mm and the length shall be at least 10 cm longerthan the needle probe. A hole shall be drilled along the axis ofthe cylinder to a depth equal to the length of the probe. Thediameter
32、 of the hole shall be equal to the diameter of the probeso that the probe fits tightly into the hole.8.4 The measured thermal conductivity of the calibrationspecimen must agree within one standard deviation of thepublished value of thermal conductivity, or with the value ofthermal conductivity deter
33、mined by an independent method.3The boldface numbers given in parentheses refer to a list of references at theend of this standard.FIG. 1 Thermal Probe Experimental SetupD53340528.5 For purposes of comparing a measured value withspecified limits, the measured value shall be rounded to thenearest dec
34、imal given in the specification limits in accordancewith the provisions of Practice D 6026.9. Procedure9.1 Allow the specimen to come to equilibrium with roomtemperature.9.2 Connect the heater wire of the thermal probe to theconstant current source. (See Fig. 1.)9.3 Connect the temperature measuring
35、 element leads to thereadout unit.9.4 Apply a known constant current (for example, equal to1.0 A) to the heater wire such that the temperature change isless than 10 K in 1000 s.9.5 Record the temperature readings at 0, 5, 10, 15, 30, 45,and 60 s, then take readings at 30-s time intervals for aminimu
36、m of 1000 s. (See Fig. 2.)9.6 Turn off the constant current source.9.7 Plot the temperature data as a function of time on asemilog graph. (See Fig. 3.)9.8 Select linear portion of curve (quasi steady state portion)and draw a straight line through the points. (See Fig. 4.)9.9 Select times t1and t2at
37、appropriate points on the lineand read the corresponding temperatures T1and T2.9.10 Perform an initial moisture content test method (seeTest Method D 2216) and a dry density test method (see TestMethod D 4439) on a representative specimen of the sample.10. Calculation10.1 Compute the thermal conduct
38、ivity (l) of the specimenfrom the linear portion of the experimental curve shown in Fig.4 using the following relationship:l52.30 Q4pT22 T1!Log10t2/t1! 5Q4pT22 T1!ln t2/t1! (1)FIG. 2 Typical Laboratory Test Data SheetFIG. 3 Typical Record of Data (Idealized Curve)D5334053where:Q = I2RL5EILQ = heat i
39、nput,l = thermal conductivity W/(mK),T1= initial temperature (K),T2= final temperature (K),t1= initial time (s),t2= final time (s),I = current flowing through heater wire (A),R = total resistance of heater wire (V),L = length of heater wire (m), andE = measured voltage (V).10.2 Derivation of Eq 1 is
40、 presented by Carslaw and Jaeger(3), and adapted to soils by VanRooyen and Winterkorn (4);VanHerzen and Maxwell (5); and Winterkorn (6).11. Report11.1 For each thermal conductivity test, fill out a data sheetsimilar to that shown in Fig. 2, reporting the following:11.1.1 Date of the test and project
41、 name or number,11.1.2 Boring number, sample or tube number, sampledepth, and data recorded in 9.5.11.1.3 Initial moisture content and dry density,11.1.4 Time versus temperature plot (see Fig. 3),11.1.5 Thermal conductivity, and11.1.6 Physical description of sample including soil or rocktype. If roc
42、k, describe location and orientation of apparentweakness planes, bedding planes, and any large inclusions orinhomogeneities.12. Precision and Bias12.1 An interlaboratory study involving line-source meth-ods, including needle probes used for rock and soils, wasundertaken by ASTM Committee C16 (7). Th
43、e materials ofknown thermal conductivity that were evaluated includedOttawa sand and paraffin wax (having a thermal conductivitysimilar to certain soil and soft rock types). The results indicateda measurement precision of between 610 and 615 % with atendency to a positive bias (higher value) over th
44、e knownvalues for the materials studied. Subcommittee D18.12 wel-comes proposals that would allow for a more comprehensiveprecision and bias statement covering the full range of soil androck materials.13. Keywords13.1 heat flow; temperature; thermal conductivity; thermalprobe; thermal propertiesANNE
45、X(Mandatory Information)A1. COMPONENTS AND ASSEMBLY OF THERMAL NEEDLEA1.1 The thermal needle consists of a stainless steelhypodermic tubing containing a heater element and a thermo-couple as shown in Fig.A1.1. Its components and assembly aresimilar to the one described by Mitchell et al (1) and Foot
46、note5.4To construct a thermal needle, hypodermic tubing is cut to115mm(412 in.) in length. The end to be inserted into thebakelite head of a thermocouple jack is roughened for a lengthof 15 mm (0.5 in.). A copper-constantan thermocouple wirejunction previously coated with an insulating varnish isthr
47、eaded into the hypodermic needle with the junction 50 mm(2 in.) from the end of the needle (see Note A1.1). At the sametime, a manganin heater element is inserted with approximately75-mm (3-in.) pigtails extending from the top of the needle asshown in Fig.A1.2. The uncut end of the needle is then in
48、sertedinto an evacuating flask through a rubber stopper and the otherend is placed in a reservoir of thermal epoxy primer as shownin Fig.A1.2.Avacuum pump connected to the evacuating flaskis used to draw the thermal epoxy up through the needle. Theneedle is removed from the reservoir and flask, and
49、a blob ofputty is placed at the end of the needle to hold the thermalepoxy in place for hardening. After the thermal epoxy hardens,the thermocouple wires are soldered to the pins of a polarizedthermocouple jack and the roughened end of the needle isplaced in the bakelite head of the jack. The heater leads arebrought out through two holes in the back of the bakelite head(see Fig. A1.1).NOTE A1.1For soft rock specimens it may not be possible to drill ahole to accommodate a 115-mm (4.50-in.) long thermal needle. In thiscase a shorter needle may be used. The lengt
