ASTM D4716-2008 Standard Test Method for Determining the (In-plane) Flow Rate per Unit Width and Hydraulic Transmissivity of a Geosynthetic Using a Constant Head《使用恒定压头测定土工合成织物(在平面.pdf

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1、Designation: D 4716 08Standard Test Method forDetermining the (In-plane) Flow Rate per Unit Width andHydraulic Transmissivity of a Geosynthetic Using aConstant Head1This standard is issued under the fixed designation D 4716; the number immediately following the designation indicates the year oforigi

2、nal adoption or, in 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 covers the procedure for determiningthe flow ra

3、te per unit width within the manufactured plane ofgeosynthetics under varying normal compressive stresses and aconstant head. The test is intended primarily as an index testbut can be used also as a performance test when the hydraulicgradients and specimen contact surfaces are selected by theuser to

4、 model anticipated field conditions.1.2 This test method is limited to geosynthetics that allowcontinuous in-plane flow paths to occur parallel to the intendeddirection of flow.1.3 The values stated in SI units are to be regarded as thestandard. The values stated in parentheses are provided forinfor

5、mation only.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 of regulatory limitations prior to use.2.

6、Referenced Documents2.1 ASTM Standards:2D 4354 Practice for Sampling of Geosynthetics for TestingD 4439 Terminology for GeosyntheticsD 4491 Test Methods for Water Permeability of Geotextilesby PermittivityD 5092 Practice for Design and Installation of GroundWater Monitoring WellsD 6574 Test Method f

7、or Determining the (In-Plane) Hy-draulic Transmissivity of a Geosynthetic by Radial Flow3. Terminology3.1 Definitions:3.1.1 geocomposite, na product fabricated from any com-bination of geosynthetics with geotechnical materials or othersynthetics which is used in a geotechnical application.(D 4439)3.

8、1.2 geonet, na geosynthetic consisting of integrallyconnected parallel sets of ribs overlying similar sets at variousangles for planar drainage of liquids or gases. (D 4439)3.1.3 geosynthetic, na planar product manufactured frompolymeric material used with soil, rock, earth, or other geo-technical e

9、ngineering related material as an integral part of aman-made project, structure, or system. (D 4439)3.1.4 geotechnics, nthe application of scientific methodsand engineering principals to the acquisition, interpretation,and use of knowledge of material of the earths crust to thesolution of engineerin

10、g problems.3.1.4.1 DiscussionGeotechnics embraces the fields of soilmechanics, rock mechanics, and many of the engineeringaspects of geology, geophysics, hydrology, and related sci-ences. (D 4439)3.1.5 geotextile, na permeable geosynthetic comprisedsolely of textiles. (D 4439)3.1.6 gravity flow, nfl

11、ow in a direction parallel to theplane of a geosynthetic driven predominantly by a difference inelevation between the inlet and outflow points of a specimen.3.1.6.1 DiscussionThe pressure at the outflow is consid-ered to be atmospheric. (D 4439)3.1.7 head (static), nthe height above a standard datum

12、 ofthe surface of a column of water (or other liquid) that can besupported by a static pressure at a given point. The static headis the sum of the elevation head and the pressure head.(D 5092)3.1.8 hydraulic gradient, i, nthe loss of hydraulic headper unit distance of flow, dh/dL. (D 4439)3.1.9 hydr

13、aulic transmissivity, u (L2T1), nfor a geosyn-thetic, the volumetric flow rate per unit width of specimen perunit gradient in a direction parallel to the plane of thespecimen.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcomm

14、ittee D35.03 on Perme-ability and Filtration.Current edition approved July 1, 2008. Published July 2008. Originally approvedin 1995. Last previous edition approved in 2007 as D 4716 07.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceast

15、m.org. For Annual Book of ASTMStandards 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.3.1.9.1 Discussion“transmissivity” is technically appli-cable

16、 only to saturated, laminar hydraulic flow conditions (seeAppendix X1). (D 4439)3.1.10 in-plane flow, nfluid flow confined to a directionparallel to the plane of a geosynthetic. (D 4439)3.1.11 index test, na test procedure that may containknown bias but which may be used to establish an order for as

17、et of specimens with respect to the property of interest.(D 4439)3.1.12 laminar flow, nflow in which the head loss isproportional to the first power of the velocity. (D 4439)3.1.13 normal stress (FL2), nthe component of appliedstress that is perpendicular to the surface on which the forceacts. (D 44

18、39)3.1.14 performance test, na test that simulates in thelaboratory as closely as practical selected conditions experi-enced in the field and which can be used in design. (D 4439)3.1.15 pressure flow, nflow in a direction parallel to theplane of a geosynthetic driven predominantly by a differentialf

19、luid pressure. (D 4439)3.1.16 turbulent flow, nthat type of flow in which anywater particle may move in any direction with respect to anyother particle, and in which the head loss is approximatelyproportional to the second power of the velocity. (D 4439)3.1.17 For definitions of terms relating to ge

20、osynthetics,refer to Terminology D 4439.3.2 Definitions of Terms Specific to This Standard:3.2.1 steady flow, nflow conditions that do not vary withtime.3.2.2 uniform flow, nconditions where the flow area andthe mean velocity in the direction of flow are constant.4. Summary of Test Method4.1 The flo

21、w rate per unit width is determined by measuringthe quantity of water that passes through a test specimen in aspecific time interval under a specific normal stress and aspecific hydraulic gradient. The hydraulic gradient(s) andspecimen contact surfaces are selected by the user either as anindex test

22、 or as a performance test to model a given set of fieldparameters as closely as possible. Measurements may berepeated under increasing normal stresses selected by the user.4.1.1 Hydraulic transmissivity should be determined onlyfor tests or for specific regions of tests that exhibit a linear flowrat

23、e per unit width versus gradient relationship, that is, laminarflow (see Appendix X1).5. Significance and Use5.1 This test method is intended either as an index test or asa performance test used to determine and compare the flow rateper unit width of one or several candidate geosynthetics underspeci

24、fic conditions.5.2 This test method may be used as an index test foracceptance testing of commercial shipments of geosyntheticsbut caution is advised since information on between-laboratoryprecision of this test method is incomplete. Comparative testsas directed in 5.2.1 may be advisable.5.2.1 In ca

25、se of a dispute arising from differences inreported test results when using this test method for acceptancetesting of commercial shipments, the purchaser and the sup-plier should first confirm that the tests were conducted usingcomparable test parameters including specimen conditioning,normal stress

26、, seating period, hydraulic gradient, test watertemperature, etc., then conduct comparative tests to determineif there is a statistical bias between their laboratories. Compe-tent statistical assistance is recommended for the investigationof bias. As a minimum, the two parties should take a group of

27、test specimens that are as homogenous as possible and that areformed from a lot of the material of the type in question. Thetest specimens should then be randomly assigned in equalnumbers to each laboratory for testing. The average resultsfrom the two laboratories should be compared using theStudent

28、s t-test for unpaired data and an acceptable probabilitylevel chosen by the two parties before the testing is begun. Ifbias is found, either its cause must be found and corrected orthe purchaser and supplier must agree to interpret future testresults in light of the known bias.6. Apparatus6.1 A sche

29、matic drawing of an assembly is shown in Fig. 1.The individual components and accessories are as follows:6.1.1 BaseA sturdy metal base with smooth flat bottomand sides capable of holding a test specimen of sufficient areaand thickness. All seams between the bottom surface and sidesof the base must b

30、e water tight and not inhibit in-plane flow ofwater through the specimen. For geotextile testing, all surfacesof the base in contact with the specimen shall be covered by athin layer of rubber material of low compressibility in order toensure a tight seal.6.1.2 ReservoirA plastic, glass or metal wat

31、er reservoirextending the full width of the base. The height of the reservoirshall be at least equal to the total length of the specimen. Thereservoir shall have provision for maintaining a constant waterlevel at any of several elevations.6.1.3 Loading MechanismCapable of sustaining a con-stant norm

32、al compressive stress on the specimen ranging from10 kPa (1.45 psi) to at least 500 kPa (70 psi) on a 305- by305-mm (12- by 12-in.) loaded area with an accuracy of 61%.The use of static weights, pneumatic bellows systems, or pistonapplied stresses meeting the above conditions may be consid-ered suff

33、icient for use in this test.6.1.4 Outflow WeirA plastic, glass or metal reservoirextending the full width of the base at the outlet side of thespecimen having, at the opposite side, a rectangular weir at anelevation higher than the elevation of the upper surface of thespecimen.FIG. 1 A Constant Head

34、 (In-Plane) Flow Rate Testing DeviceD47160826.1.5 DiscussionThe weir is used to sustain the steady,constant head condition on the outflow side of the specimen.For small discharge conditions, a narrow rectangular or trian-gular, V-notch weir may be warranted.6.1.6 Outflow CollectionA catch trough ext

35、ending theentire width of the base is used for collection and measurementof the outflow from the specimen.6.1.7 Rubber Substrate/Superstrate(optional) Rubbersheets cut to fit the base may be used to model soil adjacent tothe geosynthetic on one or both sides of the specimen ifdesired. The compressib

36、ility and thickness of the rubber layershould be selected such that it adequately represents the soilbeing modeled. The material selected should not allow con-tinuous flow channels to exist through or around the rubberlayer. These layers shall extend the entire length and width ofthe base. The thick

37、ness of the rubber layers shall be at leasttwice the thickness of the geosynthetic specimen to be tested.6.1.7.1 Compare the uncompressed thickness measuredprior to use with the thickness measured at least one hour afteruse. If the thickness decreases by 20 % or more, or ifpermanent indentations or

38、damage are evident in the sheet,discard the sheet and retest using a new sheet.6.1.8 Thickness Monitoring Device(optional) In the formof a dial gauge and the like may be used to monitor the changein the thickness of the geosynthetic specimen in the testingdevice under various applied normal stresses

39、.6.1.9 ManometersOpen manometers are located at theinlet and outlet ends of the specimen in the reservoir box andoutflow weir respectively (see Fig. 1). The manometer taps areplaced at the same level as the base of the specimen as close tothe specimen ends as practical. Extend the manometers withcle

40、ar tubing to a height at least as high as the maximum waterlevel in the reservoir box.NOTE 1The use of a pressure transducer(s) is recommended formeasuring the pressure head when testing at hydraulic gradients less than0.10. Use a transducer(s) with an accuracy of 61mm(6 0.04 in).6.2 In addition, th

41、e apparatus must not be the controllingagent for flow during the test. It will be necessary to establishcalibration curves of volumetric flow rate versus gradient forthe apparatus alone using rigid, open channel substitutes(calibration blocks) representing the range of geosyntheticthicknesses to be

42、tested in order to establish compliance withthis requirement. (See Annex A1.)7. Sampling7.1 Lot SampleDivide the product into lots and for a lot tobe tested take the lot sample as directed in Practice D 4354.7.2 Laboratory SampleConsider the units in the lotsample as the units in the laboratory samp

43、le. For the laboratorysample, take a full width swatch of sufficient length along theroll edge so that the requirements of 7.3-7.5.3 can be met.7.3 Test SpecimensGeotextilesGeotextiles should betested in accordance with Test Method D 6574.7.4 Test SpecimensGeonetsFor acceptance testing, re-move two

44、specimens from each unit in the laboratory samplewith the longer dimension parallel to the geonet direction (forexample, machine or cross-machine direction) to be tested. Thetwo test specimens are normally taken one third in from eachedge of the roll width sample swatch, but may be taken at twoother

45、 locations at the discretion of the user and noted in thereport. For performance testing, the number of test specimensis selected by the user. If one test specimen is requested forperformance testing, it is normally taken from the center of thesample swatch, but may be taken at two other locations a

46、t thediscretion of the user and noted in the report.7.4.1 Make the geonet specimen width 305 mm (12.0 in.).Make the specimen length at least 350 mm (14 in.), or thelength to allow the specimen to extend into the reservoir andweir a distance of 25 mm (1 in.), whichever is greater.7.5 Test SpecimensGe

47、ocomposites For acceptance test-ing, remove two specimens from each unit in the laboratorysample with the longer dimension parallel to the geocompositedirection (for example, machine or cross-machine direction) tobe tested. The two test specimens are normally taken one thirdin from each edge of the

48、roll width sample swatch, but may betaken at two other locations at the discretion of the user andnoted in the report. For performance testing, the number of testspecimens is selected by the user. If one test specimen isrequested for performance testing, it is normally taken from thecenter of the sa

49、mple swatch, but may be taken at two otherlocations at the discretion of the user and noted in the report.7.5.1 For geocomposites manufactured with the full productwidth less than 305 mm (12.0 in.), the specimen width is equalto the manufactured product width. The specimen length is atleast 350 mm (14 in.), or the length to allow the specimen toextend into the reservoir and weir a distance of 25 mm (1 in.),whichever is greater.NOTE 2The actual length of the geocomposite specimen may have aninfluence on the measured head losses and associate