1、Designation: D5335 08D5335 14Standard Test Method forLinear Coefficient of Thermal Expansion of Rock UsingBonded Electric Resistance Strain Gauges1This standard is issued under the fixed designation D5335; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 the case of revision, the year of last 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 the laboratory determination of the linear (one-dimensiona
3、l) coefficient of thermal expansion ofrock using bonded electric resistance strain gauges. This test method is intended for evaluation of intact rock cores. Discontinuitiesin the rock mass, such as joints, inclusions, voids, veins, bedding, and the like can influence the thermal expansion of the roc
4、k,and judgment should be used when selecting the specimen to be analyzed in this test method.1.2 This test method is applicable for unconfined pressure conditionsstress states over the temperature range from 20 to 260C(68 to 500F). 260C.NOTE 1Unconfined tests performed at elevated temperatures may a
5、lter the mineralogy or grain structure of the test specimen. This alteration maychange the physical and thermal properties of the test specimen.NOTE 2The strain gauges are mounted with epoxy. Most commercially available high temperature epoxies require elevated temperature curing. Theelevated temper
6、ature required for this curing may alter the physical and thermal properties of the test specimen. Epoxy should be selected based uponthe maximum expected test temperature. Room temperature curing epoxy should be used whenever possible. practical.1.3 The test specimens may be either saturated satura
7、ted, dry or dry.unsaturated. If saturated or unsaturated specimens are used,then the test temperature shall be at least 10C (18F) less than the boiling point of the saturating fluid in order to minimizereducethe effects of evaporation of the fluid.NOTE 3When testing a saturated specimen, the moistur
8、e gravimetric water content of the specimen may change unless special precautions are takento encapsulate the test specimen. Refer to 7.4.1.4 For satisfactory results in conformance with this test method, the principles governing the size, construction, and use of theapparatus described in this test
9、 method should be followed. If the results are to be reported as having been obtained by this testmethod, then all pertinent requirements prescribed in this test method shall be met.1.5 It is not practicable in a test method of this type to aim to establish details of construction and procedure to c
10、over allcontingencies that might offer difficulties to a person without technical knowledge concerning the theory of heat flow, temperaturemeasurement, and general testing practices. Standardization of this test method does not reduce the need for such technicalknowledge. It is recognized also that
11、it would be unwise, because of the standardization of this test method, to resist in any waythe further development of improved or new methods or procedures by research workers.1.4 UnitsThe values stated in SI units are to be regarded as the standard. The values given in parentheses are mathematical
12、conversions to inch-pound units that are provided for information only and are not considered No other units of measurement areincluded in this standard.1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in PracticeD6026.1.5.1 The m
13、ethodprocedure used to specifiyspecify how data are collected, calculated, collected/recorded or recordedcalculatedin this standard is not directly related to the accuracy to which the data can be applied in design or other uses, or both. How oneapplies the results obtained using this standard is be
14、yond its scope.are regarded as the industry standard. In addition, they arerepresentative of the significant digits that generally should be retained. The procedures used do not consider material variation,purpose for obtaining the data, special purpose studies, or any considerations for the users o
15、bjectives; and it is common practiceto increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope ofthis standard to consider significant digits used in analytical methods for engineering design.1 This test method is under the jurisdic
16、tion 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, 2008June 1, 2014. Published July 2008July 2014. Originally approved in 1992. Last previous edition approved in 20042008 asD5335 04.D5335 08. DOI: 10.
17、1520/D5335-08.10.1520/D5335-14.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 recommen
18、ds that users consult prior 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,
19、West Conshohocken, PA 19428-2959. United States11.6 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 regu
20、latoryrequirements prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and Contained FluidsD2113 Practice for Rock Core Drilling and Sampling of Rock for Site InvestigationD2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil
21、 and Rock by MassD3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD6026 Practice for Using Significant Digits in Geotechnical DataE83 Practice for Verification and Classification of Extensometer Sy
22、stemsE122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot orProcessE228 Test Method for Linear Thermal Expansion of Solid Materials With a Push-Rod DilatometerE289 Test Method for Linear Thermal Expansion of Rigid Solids with Inte
23、rferometry3. Terminology3.1 DefinitionsSee For definitions of common technical terms, refer to Terminology D653 for general definitions3.2 Definitions of Terms Specific to This Standard:3.2.1 linearmean coeffcient of linear thermal expansionexpansion, m, D/T1, n the change in length of a unit length
24、 fora temperature change of 1. The mathematical expression is: 5L22L1!/L0#31/T22T1!# (1)In terms of thermal strains: 5T22T1!/T22T1!5T/T (2)where a value, oftenT1 and expressed in partsT2 are the thermal strains of the specimen as a result of a temperaturechange from per million per degree obtained b
25、y dividing the linear thermal strain, (TL02 to T L1 and from )/TL0 to ), by thechange in temperature (T2 respectively, is obtained by dividing the change in thermal strain (T ) by the change in tem-perature (T1). The units of are millimetres/millimetre per degree Celsius (inches/inch per degree Fahr
26、enheit).3.2.1.1 DiscussionThe sign convention used for m, is as follows: m will be a positive value indicating an increase in the length of the rockspecimen, (T2 T1) and m will be a negative value indicating a decrease or contraction of the rock specimen. The coefficient oflinear thermal expansion c
27、an also be obtained by dividing the change in thermal strain (T) by the change in temperature (T).T1 and T2 are the specimen thermal strains as a result of a temperature change from T0 to T1 and from T0 to T2, respectively.3.2.2 specimen thermal strainstrain, ts, D, nthe change in length of a unit l
28、ength of a sample due to a change intemperature. The mathematical expression is:T 5L22L1L0(3)where the change in length, (L12 and L21 are the specimen lengths at temperatures ), divided by the original length, T1and T2, respectively, and L0 is, of the specimen length at the reference temperaturewhen
29、 the specimen is Tsubjected 0.to heat.3.2.2.1 DiscussionL1 and L2 are the specimen lengths at temperatures T1 and T2, respectively. L0 is the original specimen length at the referencetemperature T0.4. Summary of Test Method4.1 The In general, the application of heat to rock causes it to expand. This
30、 change in dimension of the rock when linearexpansion divided by the original length of the rock specimen is the thermal strain developed in the rock. rock specimen from2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual
31、 Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.D5335 142which the coefficients of expansion can be calculated.Awire or foil grid strain gauge suitably bonded to the rock will be is strainedprecisely the same amount as the rock. rock specim
32、en. This straining, or stretching, of the gridgauge results in a change in theelectrical resistance of the grid.gauge. Measurement of the change in the electrical resistance of the gridgauge is thus a measureof the change in linear dimension of the rock.rock specimen.4.2 The application of heat to t
33、he gridgauge may cause a change in the electrical resistance of the grid.gauge. To eliminate errorsdue to gauge heating, a second gridgauge is attached to a reference specimen and the that is not heated. During heating of the testspecimen, the output of the gauge attached to the reference specimen i
34、s subtracted from the output of the gauge attached to thetest specimen.5. Significance and Use5.1 Information concerning the thermal expansion characteristics of rocks is important in the design of any undergroundexcavation where the temperature of the surrounding rock may be altered. Thermal strain
35、 causes Depending on the restraintconditions, thermal strain may cause thermal stress that ultimately affectsmay affect the stability of underground excavations.Examples of applications where an understanding of rock thermal strain is important include: nuclear waste repositories,underground power s
36、tations, compressed air energy storage facilities, energy foundations, and geothermal energy facilities.5.2 The linear coefficient of linear thermal expansion, , of rock is known to vary as the temperature changes. Rock thermalstrain is normally not a linear function of temperature. This test method
37、 provides a procedure for continuously monitoring thermalstrain as a function of temperature. Therefore, information on how a the coefficient of linear thermal expansion changes withtemperature is obtained.5.3 Other methods of measuring the expansion coefficient of linear thermal expansion of rock b
38、y averaging the thermal strainof a large specimen over a temperature range of many degrees may result in failure to determine the variation in of that rockfor one or more of the following reasons:5.3.1 Alpha is not always linear with temperature,5.3.2 Some rocks are anisotropic having directional ch
39、aracteristics which can vary by more than a factor of two. If anisotropyis expected, specimen with different orientations should be prepared and tested.5.3.3 Alpha may have a negative value in one direction and, at the same time, a positive value in the others.5.4 Strain gauges, both Both wire and f
40、oil types, type strain gauges have been successfully employed to measure the thermalexpansion coefficients of rock. These coefficients are frequently very small, being on the order of millionths of a millimetre permillimetre for each degree Celsius (millionths of an inch per inch for each degree Fah
41、renheit). Celsius. The thermal strain of rocksis about one tenth one-tenth that of plastics and one half or one quarter one-half or one-quarter that of many metals. Therefore,measurement methods for rocks require greater precision than methods that are routinely used on plastics and metals.NOTE 4Not
42、withstanding 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 equipment and facilities used.Agenciesthat
43、meet the criteria of Practice D3740 are generally considered capable of competent and objective testing.testing/sampling/inspection/etc. Users of thistest method standard are cautioned that compliance with Practice D3740 does not in itself assureensure reliable testing.results. Reliable testingdepen
44、dsresults depend on many factors; Practice D3740 provides a means of evaluating some of those factors.6. Apparatus6.1 Bonded Strain Gauges, Gaugescorresponding to The gauges shall be ASTM Class A type resistance strain gaugeextensometer (see extensometers as described in Practice E83) The gauge leng
45、th shall be at least ten times the largest grain inthe rock. Care shall be exercised to have the same length and type of connecting wires on all specimens.6.2 Strain-Measuring System, SystemAny type having sensitivity of at least 5 m/m (5 106 in./in.) with an accuracy of atleast 60.1 % of the readin
46、g and a linearity of at least 60.1 % of the interval.6.3 Reference Specimen, Specimenhaving minimum dimensions at least twice the length of the strain gauge. The referencespecimen shall have a maximum linear coefficient of linear thermal expansion of 0.5 106 cm/cmC (0.9 10m/(m C) and haveminimum 6 i
47、n./in.F).dimensions of at least twice the length of the strain gauge.NOTE 5Suitable reference materials include titanium silicate, Zerodur, borosilicate glass, stainless steel, fused silica, and ultra-low expansion glass,all havingthat have expansion coefficients of less than 0.5 1066/C (0.9 10m/(m
48、C) 6/F) over the temperature range from 0 to 200C (32 to400F)200C.6.4 Temperature Measurement System SystemThe system chosen to monitor and record temperature depends primarily onthe test apparatus and the maximum test temperature. Special limits of error thermocouples or platinum resistance thermom
49、eters(RTDs) are recommended. The temperature sensor (transducer) shall be accurate to better than 0.2C (0.5F) 0.2C or better witha resolution of better than 0.05C (0.1F). 0.05C or better.6.5 Heating SystemThe heating unit (furnace) shall be large enough to contain the test calibration,calibration and referencespecimens such that the gauge length specified in 6.1 can be maintained at a constant temperature over its length to 0.1C (0.2F).0.1C. It shall also incorpo
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