1、Designation: D5262 07 (Reapproved 2012)Standard Test Method forEvaluating the Unconfined Tension Creep and CreepRupture Behavior of Geosynthetics1This standard is issued under the fixed designation D5262; 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. Scope1.1 This test method is intended for use in determining theunconfined tension creep and
3、creep rupture behavior of geo-synthetics at constant temperature when subjected to a sus-tained tensile loading. This test method is applicable to allgeosynthetics.1.2 The test method measures total elongation of the geo-synthetic test specimen, from the time of loading, while beingmaintained at a c
4、onstant temperature. It includes proceduresfor measuring the tension creep and creep rupture behavior atconstant temperature of conditioned geosynthetics as well asdirections for calculating tension creep and creep rupturecurves.1.3 The values stated in SI units are to be regarded as thestandard. Th
5、e values given in parentheses are for informationonly.1.4 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
6、of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing TextilesD2990 Test Methods for Tensile, Compressive, and FlexuralCreep and Creep-Rupture of PlasticsD4354 Practice for Sampling of Geosyn
7、thetics and RolledErosion Control Products(RECPs) for TestingD4439 Terminology for GeosyntheticsD4491 Test Methods for Water Permeability of Geotextilesby PermittivityD4595 Test Method for Tensile Properties of Geotextiles bythe Wide-Width Strip MethodD6637 Test Method for Determining Tensile Proper
8、ties ofGeogrids by the Single or Multi-Rib Tensile MethodE6 Terminology Relating to Methods of Mechanical Testing3. Terminology3.1 DefinitionsFor definitions of many terms used in thistest method, refer to Terminologies D123, D4439 and E6.3.2 Definitions of Terms Specific to This Standard:3.2.1 atmo
9、sphere for testing geosynthetics, nair main-tained at a relative humidity between 50 and 70 % and the test(Section 10.2).3.2.2 creep, nthe time-dependent increase in accumulativestrain in a material resulting from an applied constant force.3.2.3 design load, nthe load at which the geosynthetic isreq
10、uired to operate in order to perform its intended function.3.2.4 failure, nan arbitrary point at which a materialceases to be functionally capable of its intended use.3.2.5 geogrid, na geosynthetic formed by a regular net-work of integrally connected elements with apertures greaterthan 6.35 mm (14 i
11、n.) to allow interlocking with surroundingsoil, rock, earth, and other surrounding materials to functionprimarily as reinforcement.3.2.6 geomembrane, nan essentially impermeable geosyn-thetic composed of one or more synthetic sheets.3.2.6.1 DiscussionIn geotechnical engineering, essen-tially imperme
12、able means that no measurable liquid flowsthrough a geosynthetic when tested in accordance with TestMethods D4491.3.2.7 geosynthetic, na planar product manufactured frompolymeric material used with soil, rock, earth, or other geo-technical engineering-related material as an integral part of aman-mad
13、e project, structure, or system.3.2.8 geotextile, na permeable geosynthetic comprisedsolely of textiles.3.2.8.1 DiscussionCurrent manufacturing techniques pro-duce nonwoven fabrics, knitted (non-tubular) fabrics, andwoven fabrics.1This test method is under the jurisdiction of ASTM Committee D35 onGe
14、osynthetics and is the direct responsibility of Subcommittee D35.02 on Endur-ance Properties.Current edition approved July 1, 2012. Published July 2012. Originally approvedin 1992. Last previous edition approved in 2007 as D5262 07. DOI: 10.1520/D5262-07R12.2For referenced ASTM standards, visit the
15、ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandardsvolume information, refer to the standardss Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Uni
16、ted States13.2.9 index test, na test procedure that may contain aknown bias, but that may be used to establish an order for a setof specimens with respect to the property being measured.3.2.10 rate of creep, nthe slope of the creep-time curve ata given time.3.2.11 tensile creep rupture strength, FL1
17、,nforgeosynthetics, the force per unit width that will produce failureby rupture in a creep test in a given time, at a specified constantenvironment.3.2.12 tensile creep strain, nthe total strain at any giventime.3.2.13 wide strip tensile test, nfor geosynthetics, a tensiletest in which the entire w
18、idth of a 200-mm (8.0 in.)-widespecimen is gripped in the clamps with a gage length of 100mm (4.0 in.).4. Summary of Test Method4.1 The tension creep and creep rupture behavior of geo-synthetics is measured by applying a sustained load in one stepand measuring the total elongation of the test specim
19、en as afunction of time while maintaining a specified temperature andhumidity.5. Significance and Use5.1 This test method is developed for use in the determina-tion of anticipated total elongation or time to rupture that mayoccur in geosynthetics under sustained loading conditions.5.1.1 The test dat
20、a can be used in conjunction with inter-pretive methods to evaluate creep strain potential at designloads.5.1.2 The test data can be used in conjunction with inter-pretive methods to evaluate creep rupture potential at variousloads.5.2 This test method is not intended for routine acceptancetesting o
21、f geosynthetics. This test method should be used tocharacterize geosynthetics intended for use in applications inwhich creep or creep rupture is of concern. The plane strain orrupture condition imposed during testing must be consideredwhen using the test results for design.5.3 The basic distinctions
22、 between this test method andother test methods for measuring tension creep and creeprupture behavior are (1) the width of the specimens (Section 8)and (2) the measurement of total elongation or time to rupturefrom the moment of specimen loading. The greater widths ofthe specimens specified in this
23、test method minimize thecontraction edge effect (necking) that occurs in many geosyn-thetic materials and provides a closer relationship to actualmaterial behavior in plane strain tension conditions.5.4 The creep or stress rupture of a given geosynthetic islikely to be reduced in soil because of loa
24、d transfer to the soil.The unconfined environment represents a controlled test, inwhich the results are conservative with regard to the behaviorof the material in service. Confined or in-soil testing maymodel the field behavior of the geosynthetic more accurately.6. Apparatus6.1 Clamps:6.1.1 Clamps
25、should be at least as wide as the specimen,with appropriate clamping power that will prevent slipping ordamage of the test specimen within or at the faces of theclamps. The clamps and clamping technique shall be designedto minimize eccentric loading of the specimen. A swivel oruniversal joint shall
26、be used on one of the clamps at the end ofthe specimen. It is recommended that clamps permit the finalcentering of the specimen prior to application of the load.36.1.2 Geotextiles and Geomembranes Each clamp shallbe sufficiently wide to grip the entire width of the specimen,200 mm (8.0 in.), and a m
27、inimum of 50-mm (2.0-in.) length inthe direction of the applied force.6.1.3 GeogridsThese should be clamped to assure com-plete tension load transfer through test direction members. Thetype of clamp and load transfer mechanism should be detailedin the test report. Roller grips or low melting point a
28、lloy withadequate strength may be used to assist proper clamping. SeeTest Method D6637.6.1.4 Other Related ProductsWhere special clamps areused to grip these products, they should conform to the generalrequirements for clamps used to grip geotextiles,geomembranes, and geogrids, and the clamping meth
29、ods usedshould always be detailed in the report.6.2 Loading System The loading system must be designedso that the load applied and maintained on the specimen iswithin 61 % of the desired load. Loads may be applied byweights, weights and fulcrums, or pneumatics. The loadingmechanism must permit repro
30、ducibly rapid and smoothloading, as specified in 11.4. No dynamic forces on placementof the loads shall be allowed. Provision must also be made toensure that shock loading, caused by specimen failure, is nottransferred to other specimens undergoing testing.36.3 Extension MeasurementExtensometers are
31、 preferredfor the measurement of elongation in geosynthetics. Wheneverpossible, other means of measuring elongation should becalibrated against extensometers. In any case, the devicechosen shall be capable of measuring deformations to anaccuracy of at least 0.003 6 mm (0.0001 6 in.). The means ofmea
32、suring elongation should be indicated clearly in the report.6.4 Vibration ControlCreep and creep rupture tests aresensitive to shock and vibration. The location of the apparatus,test equipment, and mounting shall be designed so that thespecimen is isolated from vibration. Multi-station test equip-me
33、nt must be of sufficient rigidity so that no significantdeflection due to shock or vibration occurs during testing.6.5 Time Measurement The accuracy of the time measur-ing device shall be 61 % of the elapsed time of each creep orcreep rupture measurement load increment.6.6 Temperature Control and Me
34、asurement:6.6.1 The temperature in the test space, especially close tothe gage length of the specimen, shall be maintained within62.0C (63.6F) of the targeted value by a suitable automaticdevice and shall be stated in the report. It is generally3Examples of clamping, loading, and extensometer system
35、s that have been usedsuccessfully are found in the appendixes.D5262 07 (2012)2recognized that thermal contraction and expansion, associatedwith small temperature changes during the test, may producechanges in the apparent creep rate, especially near the transi-tion temperature.6.6.2 Temperature meas
36、urements shall be recorded at fre-quent intervals, or recorded continuously, in order to ensure anaccurate determination of the average test temperature andcompliance with 6.6.1.6.7 Environmental Control and Measurement:6.7.1 When the test environment is air, the relative humidityshall be maintained
37、 between 50 and 70 % unless the creep orcreep rupture behavior of the geosynthetic has been shown tobe unaffected by humidity. The relative humidity shall berecorded at frequent intervals to ensure that an accuratedetermination of the average test humidity can be made.6.7.2 The test environment shal
38、l be maintained constantthroughout the test. Safety precautions should be taken to avoidpersonal contact during the test. The area should be isolatedadequately and fenced such that only the test operator hasaccess to the test station.7. Sampling7.1 Laboratory SampleFor the laboratory sample, take af
39、ull-width swatch at least 1-m (40-in.) long in the machinedirection from each roll in the lot sample. The sample may betaken from the end portion of a roll, provided there is noevidence that it is different from other portions of the roll. SeePractice D4354.7.2 Test Specimens:7.2.1 Geotextiles and G
40、eomembranes For tests in themachine and cross-machine directions, respectively, take fromeach sample the number of specimens as directed in 9.1. Takethe specimens from a diagonal on the sample, with nospecimens closer than110 the width of the roll or 150 mm (6in.), whichever is smaller. For geomembr
41、anes, exercise care inselecting, cutting, and preparing the specimens to avoid nicks,tears, scratches, folds, or other imperfections that are likely tocause premature failure.NOTE 1Nonreinforced geomembranes are extremely sensitive in thisregard.7.2.2 Geogrids and Other Related ProductsFor tests int
42、he machine and cross-machine directions, respectively, takefrom each sample the number of specimens as directed in 9.1.Take the specimens at random from the laboratory sample. Formeasurement of machine direction properties, take specimensfrom different positions across the width of the sample. For t
43、hemeasurement of cross-machine direction properties, take speci-mens from different positions along the length of the sample.Take no specimens nearer to the edge than1/10 the width of theroll or 150 mm (6 in.), whichever is smaller.8. Test Specimen8.1 Geosynthetics Prepare each finished specimen tos
44、pecimen to the width appropriate for the particular geosyn-thetic with the length dimension parallel to the direction thatthe creep or creep rupture behavior is being measured.8.1.1 Geotextiles Prepare specimen width to 200 mm (8.0in) wide by at least 200 mm (8.0 in) long.8.1.2 GeogridsPrepare speci
45、men width to include at leastthree longitudinal elements abreast parallel to the direction thatthe creep or creep rupture behavior is being measured witheach element long enough to include at least three apertures, asillustrated in Fig. X2.1.8.2 The length of the specimen depends on the type ofclamp
46、s being used. The specimen must be long enough toextend through the full length of both clamps, as determinedfor the direction of the test.8.3 When specimen integrity is not affected, the specimenmay be cut initially to the finished width.8.4 This test method may not be suitable for some wovengeotex
47、tiles or geogrids that exhibit breaking strengths in excessof 100 kN/m (570 lbf/in.), due to clamping and equipmentlimitations.9. Number of Tests9.1 Unless otherwise agreed upon, creep and creep rupturetests shall be conducted at load levels as specified by thedesigner. Four load levels are recommen
48、ded for characteriza-tion of the material. Loads shall be selected at intervals ofapproximately 10 % of the maximum load per unit width asdetermined by applicable ASTM test methods.9.1.1 For creep test, the loads should be 20, 30, 40, 50 and60 % of the ultimate tensile strength of the sample being t
49、ested,unless otherwise agreed upon by the parties involved.9.1.2 For creep rupture tests, the loads should be 50, 60, 70,80, and 90 % of the ultimate tensile strength of the samplebeing tested, unless otherwise agreed upon by the partiesinvolved.NOTE 2It is generally recognized that characterization involvesidentification of the load levels at which there is no creep (no increase instrain with the log of time), low to moderate creep (linear increase in strainwith the log of time), and high creep (exponential increase in strain withthe log of ti
