ASTM D6706-2001(2007) Standard Test Method for Measuring Geosynthetic Pullout Resistance in Soil《测量土壤中土工合成织物拉起阻力的标准试验方法》.pdf

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1、Designation: D 6706 01 (Reapproved 2007)Standard Test Method forMeasuring Geosynthetic Pullout Resistance in Soil1This standard is issued under the fixed designation D 6706; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year

2、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. Scope1.1 Resistance of a geosynthetic to pullout from soil isdetermined using a laboratory pullout box.1.2 The test method

3、is intended to be a performance testconducted as closely as possible to replicate design or as-builtconditions. It can also be used to compare different geosyn-thetics, soil types, etc., and thereby be used as a research anddevelopment test procedure.1.3 The values stated in SI units are to be regar

4、ded asstandard. The values stated in parentheses are provided forinformation only.1.4 This standard may involve hazardous materials, andequipment. 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 standar

5、d to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 123 Terminology Relating to TextilesD 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 3080 Test Method for Direct

6、Shear Test of Soils UnderConsolidated Drained ConditionsD 4354 Practice for Sampling of Geosynthetics for TestingD 4439 Terminology for Geosynthetics3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 apertures, nthe open spaces in geogrids whichenable soil interlocking to occur.3

7、.1.2 atmosphere for testing geosynthetics, nair main-tained at a relative humidity of 60 6 10 % and a temperatureof 21 6 2C (70 6 4F).3.1.3 cross-machine direction, nthe direction in the planeof the geosynthetic perpendicular to the direction of manufac-ture.3.1.4 failure, na defined point at which

8、a material ceasesto be functionally capable of its intended use.3.1.5 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-made project, structure, or system. (D 4439)3.1.6 jun

9、ction, nthe point where geogrid ribs are intercon-nected in order to provide structure and dimensional stability.3.1.7 machine direction, nthe direction in the plane of thegeosynthetic parallel to the direction of manufacture.3.1.8 pullout, nthe movement of a geosynthetic over itsentire embedded len

10、gth, with initial pullout occurring when theback of the specimen moves, and ultimate pullout occurringwhen the movement is uniform over the entire embeddedlength.3.1.9 pullout force, (kN), nforce required to pull a geo-synthetic out of the soil during a pullout test.3.1.10 pullout resistance, (kN/m)

11、, nthe pullout force perwidth of geosynthetic measured at a specified condition ofdisplacement.3.1.11 rib, nthe continuous elements of a geogrid whichare either in the machine or cross-machine direction asmanufactured.3.1.12 ultimate pullout resistance, (kN/m), nthe maxi-mum pullout resistance measu

12、red during a pullout test.3.1.13 wire gage, na displacement gage consisting of anon extensible wire attached to the geosynthetic and monitoredby connection to a dial extensometer, or electronic displace-ment transducer.3.2 For definitions of other terms used in this test methodrefer to Terminology D

13、 123, D 653, and D 4439.4. Summary of Test Method4.1 In this method, a geosynthetic is embedded between twolayers of soil, horizontal force is applied to the geosyntheticand the force required to pull the geosynthetic out of the soil isrecorded.4.2 Pullout resistance is obtained by dividing the maxi

14、mumload by the test specimen width.4.3 The test is performed while subjected to normal com-pressive stresses which are applied to the top soil layer.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-ca

15、l Properties.Current edition approved June 1, 2007. Published July 2007. Originally approvedin 2001. Last previous edition approved in 2001 as D 670601.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSta

16、ndards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4 A plot of maximum pullout resistance versus appliednormal stress is obtained by conducting

17、 a series of such tests.5. Significance and Use5.1 The pullout test method is intended as a performancetest to provide the user with a set of design values for the testconditions examined.5.1.1 The test method is applicable to all geosynthetics andall soils.5.1.2 This test method produces test data,

18、 which can be usedin the design of geosynthetic-reinforced retaining walls, slopes,and embankments, or in other applications where resistance ofa geosynthetic to pullout under simulated field conditions isimportant.5.1.3 The test results may also provide information relatedto the in-soil stress-stra

19、in response of a geosynthetic underconfined loading conditions.5.2 The pullout resistance versus normal stress plot obtainedfrom this test is a function of soil gradation, plasticity,as-placed dry unit weight, moisture content, length and surfacecharacteristics of the geosynthetic and other test par

20、ameters.Therefore, results are expressed in terms of the actual testconditions. The test measures the net effect of a combination ofpullout mechanisms, which may vary depending on type ofgeosynthetic specimen, embedment length, relative openingsize, soil type, displacement rate, normal stress, and o

21、therfactors.5.3 Information between laboratories on precision is incom-plete. In cases of dispute, comparative tests to determine ifthere is a statistical bias between laboratories may be advis-able.6. Apparatus6.1 Pullout BoxAn open rigid box consisting of twosmooth parallel sides, a back wall, a h

22、orizontal split removabledoor, a bottom plate, and a load transfer sleeve. The door is atthe front as defined by the direction of applied pullout force. Atypical box is shown in Fig. 1.6.1.1 The box should be square or rectangular with mini-mum dimensions 610 mm (24 in.) long by 460 mm (18 in.)wide

23、by 305 mm (12 in.) deep, if sidewall friction is mini-mized, otherwise the minimum width should be 760 mm (30in.). The dimensions should be increased, if necessary, so thatminimum width is the greater of 20 times the D85 of the soilor 6 times the maximum soil particle size, and the minimumlength gre

24、ater than 5 times the maximum geosynthetic aperturesize. The box shall allow for a minimum depth of 150 mm (6in.) above and below the geosynthetic. The depth of the soil inthe box above or below the geosynthetic shall be a minimum of6 times the D85 of the soil or 3 times the maximum particlesize of

25、the soil, whichever is greater. The box must allow for atleast 610 mm (24 in.) embedment length beyond the loadtransfer sleeve and a minimum specimen length to width ratioof 2.0. It should be understood that when testing large aperturegeosynthetics the actual pullout box may have to be larger thanth

26、e stated minimum dimensions.NOTE 1To remove side wall friction as much as possible a highdensity polyethylene (HDPE) geomembrane should be bonded to theinside surfaces of the pullout box. The sidewalls may also be covered witha layer of silk fabric, which has been shown to eliminate adhesion and has

27、a very low friction value. Alternatively, a lubricant can be spread on thesidewalls of the box and thin sheets of polyethylene film used to minimizethe side wall friction. It should be also noted that the effect of sidewallfriction on the soil-geosynthetic interface can also be eliminated if aminimu

28、m distance is kept between the specimen and the side wall. Thisminimum distance is recommended to be 150 mm (6 in.).6.1.2 The box shall be fitted with a metal sleeve at theentrance of the box to transfer the force into the soil to asufficient horizontal distance so as to significantly reduce thestre

29、ss on the door of the box. The sleeve, as shown in Fig. 2,shall consist of two thin plates (no more than 13 mm (0.5 in.)thick) extending the full width of the pullout box and into theFIG. 1 Experimental Set-Up for Geosynthetic Pullout TestingD 6706 01 (2007)2pullout box a minimum distance of 150 mm

30、(6 in.) but it isrecommended that this distance equal the total soil depth aboveor below the geosynthetic. The plates shall be tapered as shownin Fig. 2, such that at the point of load application in the soil,the plates forming the sleeve are no more then 3 mm (0.12 in.)thick. The plates shall be ri

31、gidly separated at the sides withspacers and be sufficiently stiff such that normal stress is nottransferred to the geosynthetic between the plates.6.2 Normal Stress Loading DeviceNormal stress appliedto the upper layer of soil above the geosynthetic must beconstant and uniform for the duration of t

32、he test. To maintaina uniform normal stress, a flexible pneumatic or hydraulicdiaphragm-loading device which is continuous over the entirepullout box area should be used and capable of maintaining theapplied normal stress within 62 % of the required normalstress. Normal stresses utilized will depend

33、 on testing require-ments, however, stresses up to 250 kPa (35 psi) should beanticipated.Arecommended normal stress-loading device is anair bag is shown in Fig. 2.6.3 Pullout Force Loading DevicePullout force must besupplied by a device with the ability to pull the geosynthetichorizontally out of th

34、e pullout box. The force must be at thesame level with the specimen. The pullout system must be ableto apply the pullout force at a constant rate of displacement,slow enough to dissipate soil pore pressures as outlined in TestMethod D 3080. If excess pore pressures are not anticipatedand in the abse

35、nce of a material specification, apply the pulloutforce at a rate of 1 mm/min 610 percent, and the pullout rateshould be monitored during testing, see Note 2. Also, a deviceto measure the pullout force such as a load cell or proving ringmust be incorporated into the system and shall be accuratewithi

36、n 60.5 % of its full-scale range.NOTE 2Pullout tests may also be conducted using a constant stressloading approach. This approach can be achieved using one of the threemethods described: (1) Controlled Stress Rate Method (short-term loadingcondition) where the pullout force is applied to the geosynt

37、hetic under auniform rate of load application, not exceeding 2 kN/m/min until pulloutor failure of the geosynthetic is achieved; (2) Incremental Stress Method(short-term loading condition) where the pullout force is applied inuniform or doubling increments and held for a specific time beforeproceedi

38、ng to the next increment, as agreed to by the parties involved untilpullout or failure of the geosynthetic is achieved; and (3) Constant Stress(Creep) Method (long-term loading condition) where the pullout force isapplied using one of the first two methods mentioned above to achieve therequired cons

39、tant stress for the test. The constant stress is maintained andthe test specimen is monitored over time for the duration of time agreedto by the parties involved (i.e., typically 100 to 10,000 h depending onapplication). It should be noted that the constant stress proceduresdescribed above, have not

40、 been widely researched and comparisons withthe constant strain method have not been determined.6.4 Displacement IndicatorsHorizontal displacement ofthe geosynthetic is measured at the entrance of the pullout boxand at several locations on the embedded portion of thespecimen. Measurements outside th

41、e door at the pullout boxFIG. 2 Cross-Sectional Detail View for Geosynthetic Pullout SetupD 6706 01 (2007)3entrance are made by a dial extensometer or electronic dis-placement transducers (e.g. liner variable differential trans-formers (LVDTs) can be used) mounted to the box frame toread against a p

42、late attached to the specimen near the door.6.4.1 Determine the displacement of the geosynthetic at aminimum of three equally spaced distances from the clampingplates. Displacement measurements within the box may em-ploy any of several methods, which place sensors or gaugeconnectors directly on the

43、geosynthetic and monitor theirchange in location remotely. One such device utilizes wiregages, which are protected from normal stress by a surroundingtube, which runs from a location mounted on the specimen tothe outside of the box where displacements are measured by adial indicator or electronic di

44、splacement transducer. A typicalinstrumentation setup is shown in Fig. 3.6.4.2 All dial gauges or electronic measurement devicesmust be accurate to 6 0.10 mm. Locations of the devices mustbe accurately determined and recorded. Minimum extensioncapabilities of 50 mm (2 in.) are recommended.6.5 Geosyn

45、thetic Clamping DevicesClamps which con-nect the specimen to the pullout force system without slipping,causing clamp breaks or weakening the material may be used,see Note 3. The clamps shall be swiveled to allow the pullingforces to be distributed evenly through out the width of thesample. The clamp

46、s must allow the specimen to remainhorizontal during loading and not interfere with the pullout/shear surface. Gluing, bonding, or otherwise molding of ageosynthetic within the clamp area is acceptable and recom-mended whenever slippage might occur.NOTE 3A suggested device is shown in Fig. 4 and inc

47、ludes a simpleclamp consisting of two, 100 mm (4 in.) wide metal angle pieces with aseries of bolts and nuts holding the material between them. One possiblemodification is the addition of a metal rod behind the back flange whichallows looping of the material around the rod and back into the clamp. T

48、heuse of epoxy bonding within the clamp is generally recommended whenaccurate measurement of the geosynthetic displacements within the soilare required.6.6 Soil Preparation EquipmentUse equipment as neces-sary for the placement of soils at desired conditions. This mayinclude compaction devices such

49、as vibratory or “jumping-jack” type compaction, or hand compaction hammers. Soilcontainer or hopper, leveling tools and soil placement/removaltools may be required.6.7 Miscellaneous EquipmentMeasurement and trimmingequipment as necessary for geosynthetic preparation, a timingdevice and soil property testing equipment if desired.7. Geosynthetic Sampling7.1 Lot SampleDivide the product into lots and for any lotto be tested, take the lot samples as directed in Practice D 4354,see Note 4.NOTE 4Lots of geosynthetics are usually designated by the producerduring