1、Designation: D4535 08D4535 13Standard 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
2、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*Scope1.1 These test methods cover the laboratory measurement of the one-dimensional linear (one-dimensional) thermal expa
3、nsionof rocks using a dilatometer.1.2 These test methods are applicable between temperatures of 25C to 300C. Both bench top and confined measurementtechniques are presented. Test MethodAis used for unconfined or bench top measurements and Test Method B is used for confinedconditions. Rocks of varyin
4、g moisture content can be tested.1.3 For satisfactory results in conformance with these test methods, the principles governing the size, construction, and use ofthe apparatus described in these test methods should be followed. If the results are to be reported as having been obtained by thiseither t
5、est method, then allthe pertinent requirements prescribed in this by that test method shall be met.1.4 These test methods do not establish details of construction and procedureprocedures to cover all test situations that mightoffer difficulties to a person without technical knowledge concerning the
6、theory of heat flow, temperature measurement, and generaltesting practices. Standardization of these test methods does not reduce the need for such technical knowledge. It is recognized alsothat it would be unwise, because of the standardization of this method, to resist in any way the further devel
7、opment of improvedor new methods or procedures by research workers.1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in PracticeD6026.1.6 The procedures used to specify how data are collected/recorded or calculated, in this standar
8、d are regarded as the industrystandard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do notconsider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the users objectives;and
9、 it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations.It is beyond the scope of this standard to consider significant digits used in analytical methods for engineering design.1.7 The values stated in SI units are to be regarded
10、as the standard. The values given in parentheses are mathematicalconversions to inch-pound units that are provided for information only and are not considered standard.1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityo
11、f the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and Contained FluidsD2216 Test Methods for Laboratory Determinati
12、on of Water (Moisture) Content of Soil 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 Data1 These test methods are unde
13、r the jurisdiction ofASTM Committee D18 on Soil and Rock and are the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved July 1, 2008Nov. 1, 2013. Published July 2008December 2013. Originally approved in 1985. Last previous edition approved in 2004 asD4535 85 (200
14、4).D4535 08. DOI: 10.1520/D4535-08.10.1520/D4535-13.2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume information, refer to the standards Document Summary page on the ASTM website.This do
15、cument 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 recommends that users consult prior editions a
16、s 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, West Conshohocken, PA 19428-2959. Unit
17、ed States1E122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot orProcessE83 Practice for Verification and Classification of Extensometer SystemsE228 Test Method for Linear Thermal Expansion of Solid Materials With a Push-Rod Dilat
18、ometer3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 For definitions of common technical terms in this standard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 samplespecimen thermal strain, tchange in length of a unit length of sample when
19、 the sample is subjected to heat. Themathematical expression is: t 5L22L1!/L 0 (1)where:L1 and L2 = specimen lengths corresponding to temperatures T1 and T2, andL0 = the original specimen length at some reference temperature T0.Thermal change in length, (L2 L1), divided by the original length, L0, o
20、f the specimen when the specimen is subjected to heat.Specimen thermal strain is also equal to the specimencorrected thermal displacement,expansion, t, divided by the original samplelength: specimen length.t 5t/L 0 (2)3.2.2 mean coeffcient of linear expression,expansion, mbetween two temperatures, a
21、 value, often expressed in parts permillion per degree. It is obtained by dividing the linear thermal strain, (TL12 and TL21,)/L0 is defined as follows:), by the changeinm 5L 22L1!/L0T22T1!# (3)temperature units cm/cm (in./in.) per temperature change in C (F).where:L1 and L2 = specimen lengths at te
22、mperatures T1 and T2, respectively. Therefore, m is obtained by dividing the linear thermalstrain, (L1 L2)/L0, by the change in temperature units are inch/inch or centimetre/centimetre per temperaturechange in F or C, respectively. m is often expressed in parts per million per degree.3.2.3 Upon heat
23、ing The sign convention used for m is as follows: m will be a positive value indicating an increase in the lengthof the rock specimen (T2 T1), an increase in the length of the rock sample will give a positive value of ) and m. If a decreasein length (contraction) is observed, will be a negative valu
24、e indicating a decrease or contraction of the rock specimenm willbecome negative.3.1.4 For definitions of other terms used in these test methods, see Terminology D653.4. Summary of Test Methods4.1 The application of heat to a rock causes it to expand. This expansion divided by the original length of
25、 the rockspecimensspecimen is the thermal strain from which coefficients of expansion can be calculated. This standard covers two methodsfor measuring rock expansion. The primary difference between the two methods is in the type of dilatometer used.4.1.1 Test Method ITest Method IA is the procedure
26、used when making unconfined or bench top measurements. The methodand apparatus are similar to that described in Test Method E228. The rock specimenspecimens thermal displacement is measuredusing a dilatometer as shown in Fig. 1. The samplespecimen displacement is measured by a transducer located out
27、side the heatedarea of the sample;specimen; therefore, apparent strain due to apparatus expansion and contraction is minimized.4.1.2 Test Method IITest Method II B is most suited for the measurement of rock thermal strain under confined conditionsand employs a dilatometric device which is located in
28、side the heated zone, as shown in Fig. 2. This test method is most suited forthe measurement of rock thermal strain under confined conditions.Test Method B is amenable to confined thermal straindeterminations; however, confined tests may be most appropriate when:4.1.2.1 Pore pressure must be imposed
29、 in the pore space to maintain the liquid phase of water through the desired temperaturerange.4.1.2.2 The thermal strain of the rock is sensitive to confining stress.4.1.2.3 The specimen is fragile or friable, or both, and cannot be machined into the shapes required for Test Method A.4.2 In both tes
30、t methods, samplespecimen expansion is measured continuously as temperature is gradually increased or allowedto stabilize at discrete temperature points.5. Significance and Use5.1 Information concerning the thermal expansion characteristics of rocks is important in the design of any undergroundexcav
31、ation where the surrounding rock may be heated. Thermal strain causes thermal stresses which ultimately affect excavationD4535 132stability. Examples of applications where rock thermal strain is important include: nuclear waste repositories, underground powerstations, compressed air energy storage f
32、acilities, and geothermal energy facilities.5.2 The coefficient of thermal expansion or “alpha” or expansion, , of rock is known to vary as the temperature changes. Thesemethods provide continuous thermal strain values as a function of temperature, and therefore provide information on how alphathe c
33、oefficient of thermal expansion changes with temperature.5.3 Rocks are also often anisotropic, thus displaying different thermal strains depending on the orientation of strainmeasurement. These methods allow for measuring strain in one direction only. If anisotropy is expected, samplesspecimens with
34、different orientations should be prepared and tested.NOTE 1The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of theequipment and facilities used.Agencies that meet the criteria of Practice D3740 are generally consid
35、ered capable of competent and objective testing. Usersof this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors;Practice D3740 provides a means of evaluating some of those factors.5.4 Care should be exercise
36、d in the interpretation of thermal strain data of rocks with significant moisture content. Under certaintemperature and pressure conditions, steam may be produced in the pore space. Steam may cause errors because of microcrackproduction or changes in the pore pressure. The phase change from water to
37、 steam in the pore space can result in severalphenomena which complicate data analysis, as follows:5.4.1 Evolved steam may change the pore pressure and thus the effective stress in the rock, resulting in anomalous strainreadings.5.4.2 Losing all the moisture may dehydrate clays in the pore space and
38、 thus change expansion characteristics, especially inlayered rocks.5.5 The researcher using this standard must use best judgment as to how to make the thermal expansion measurement so thatit accurately represents the conditions in the field.5.6 Method II is amenable to confined thermal strain determ
39、inations. Confined tests may be most appropriate when:5.6.1 Pore pressure must be imposed in the pore space to maintain the liquid phase of water through the desired temperaturerange.5.6.2 The thermal strain of the rock is sensitive to confining stress.5.6.3 The sample is fragile or friable, or both
40、, and cannot be machined into the shapes required for Method I.6. Interferences6.1 Care should be exercised in the interpretation of thermal strain data of rocks with significant moisture content. Under certaintemperature and pressure conditions, steam may be produced in the pore space. Steam may ca
41、use errors because of microcrackFIG. 1 Apparatus Commonly Used to Perform Bench Top (Method I) (Test Method A) Thermal Expansion MeasurementsD4535 133production or changes in the pore pressure. The phase change from water to steam in the pore space can result in severalphenomena which complicate dat
42、a analysis, as follows:6.1.1 Evolved steam may change the pore pressure and thus the effective stress in the rock, resulting in anomalous strainreadings.6.1.2 Losing all the moisture may dehydrate clays in the pore space and thus change expansion characteristics, especially inlayered rocks6.1.3 Good
43、 judgment should be used when deciding how to make the thermal expansion measurement so that it accuratelyrepresents the conditions in the field.7. Apparatus7.1 Dilatometer:7.1.1 Test Method IAThe dilatometer used for bench measurements may be of the tube or rod type, as shown in Fig. 1.Thosecompone
44、nts of the dilatometer exposed to elevated temperatures should be fabricated of materials with coefficients of linearexpansion that are as small as practicable.7.1.2 Test Method IIBIn Method II the The entire dilatometer is exposed to elevated temperature. Therefore,temperature;therefore, transducer
45、s, rods, and other components should be fabricated of materials with low thermal expansions (forexpansions.For example, fused silica, and super invar).invar. When the apparatus is tested with a quartz calibration specimen, the apparatusstrain should be less than 20 % of the anticipated rock strain (
46、refer to Fig. 2).FIG. 2 Apparatus Commonly Used to Perform Confined (Method II) (Test Method B) Thermal Expansion MeasurementsD4535 1347.2 ExtensometerExtensometers measure length change. In principle, any accurate length measuring device with goodlong-term stability may be used; this includes inclu
47、ding dial gauges, linear variable differential transducers, or capacitivetransducers. Whichever device is selected, it must have sufficient resolution to measure 0.01 % samplespecimen strain (Refer toPractice E83).7.2.1 Those devices Devices used in Test Method IIB must be fabricated of materials th
48、at allow direct exposure of the deviceto the anticipated temperature. Also, transducer bodies should be vented for operation in a pressure environment. At least twotransducers are used, as shown in Fig. 2, and their outputs averaged.7.3 FurnaceThe furnace shall be large enough to contain the specime
49、n and apparatus and maintain uniform temperature alongthe axis of the specimen with variations no greater than 61C. The mean sample temperature shall be controlled within 61C.The use of a programmable temperature controller that can slowly increase or decrease samplespecimen temperatures at rates atleast as low as 0.1C/min is recommended.7.4 Temperature Measuring Instruments Thermocouples or platinum resistant thermometers are recommended. The exacttype will depend on the temperature range of interest. In general, the tempera
