1、Designation: D 6766 06aStandard Test Method forEvaluation of Hydraulic Properties of Geosynthetic ClayLiners Permeated with Potentially Incompatible Liquids1This standard is issued under the fixed designation D 6766; the number immediately following the designation indicates the year oforiginal adop
2、tion or, in the case of revision, the year 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 This test method covers laboratory measurement of bothflux and hydrauli
3、c conductivity (also referred to as coeffcientof permeability) of geosynthetic clay liner (GCL) specimenspermeated with chemical solutions and leachates utilizing aflexible wall permeameter. For test measurement of indexhydraulic properties of geosynthetic clay liners, refer to TestMethod D 5887.1.2
4、 This test method may be utilized with GCL specimensthat have a hydraulic conductivity less than or equal to1 3 10-5m/s (1 3 10-3cm/s).1.3 This test method is applicable to GCL products havinggeotextile backing(s). It may not be applicable to GCL prod-ucts with geomembrane backing(s).1.4 This test m
5、ethod provides measurements of flux andhydraulic conductivity under a prescribed set of conditions, asan index test, that can be used for manufacturing qualitycontrol. The flux and hydraulic conductivity values determinedusing this test method under the prescribed set of conditions isnot considered
6、to be representative of the in-service conditionsof GCLs. However, the test method allows the requester toestablish a set of test conditions; thus, the test method also maybe used to check performance or conformance, or both.1.5 The values stated in SI units are to be regarded as thestandard, unless
7、 other units are specifically given. By traditionin U.S. practice, hydraulic conductivity is reported in centime-ters per second, although the common SI units for hydraulicconductivity are meters per second.1.6 This standard does not purport to address all of thesafety concerns, if any, associated w
8、ith 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. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 22
9、16 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 4439 Terminology for GeosyntheticsD 4753 Guide for Evaluating, Selecting, and SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD 5887 Test Method for Meas
10、urement of Index FluxThrough Saturated Geosynthetic Clay Liner SpecimensUsing a Flexible Wall PermeameterE 145 Specification for Gravity-Convection And Forced-Ventilation Ovens3. Terminology3.1 Definitions:3.1.1 flux, nthe rate of discharge of liquid under laminarflow conditions through a unit cross
11、-sectional area of a GCLspecimen at a standard temperature condition (22 6 3C).3.1.2 geosynthetic clay liner (GCL), na factory-manufactured geosynthetic hydraulic barrier consisting of claysupported by geotextiles, geomembranes, or a combinationthereof, that are held together by needling, stitching,
12、 chemicaladhesives or other methods.3.1.3 hydraulic conductivity, k, nthe rate of discharge ofliquid under laminar flow conditions through a unit cross-sectional area of a GCL specimen under a unit hydraulicgradient and standard temperature conditions (22 6 3C).3.1.3.1 DiscussionThe term coeffcient
13、of permeability isoften used instead of hydraulic conductivity but hydraulicconductivity is used exclusively in this test method. A more1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.04 on Geosyn-thetic Clay Line
14、rs.Current edition approved Nov. 15, 2006. Published December 2006. Originallyapproved in 2002. Last previous edition approved in 2006 as D 676606.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandard
15、s 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 Splete discussion of the terminology associated with Dar-cys law is given in the literature.33.1.4 index t
16、est, na test procedure that may contain bias,but may be used to establish comparable results with respect tothe property of interest.3.1.5 pore volume of flow, nthe cumulative quantity offlow into a test specimen divided by the volume of voids in thespecimen.3.2 For definitions of other terms used i
17、n this test method,see Terminology D 653 and D 4439.4. Significance and Use4.1 This test method applies to one-dimensional, laminarflow of water or other permeation liquids, such as chemicalsolutions, landfill leachate, and contaminated water (here onreferred to as test liquid), through saturated/hy
18、drated GCLspecimen that is consolidated and permeated under a pre-scribed or requested set of conditions.4.2 This test method can be performed to determine if theflux and/or hydraulic conductivity of a GCL specimen exceedsthe maximum value stated by the manufacturer or required bythe regulatory agen
19、cies, or both.4.3 It is assumed that Darcys law is valid and that thehydraulic conductivity is essentially unaffected by hydraulicgradient. The validity of Darcys law may be evaluated bymeasuring the hydraulic conductivity of the specimen at threedifferent hydraulic gradients; if all measured values
20、 are similar(within about 25 %), then Darcys law may be taken as valid.However, when the hydraulic gradient acting on a test speci-men is changed, the state of stress will also change, and, if thespecimen is compressible, the volume of the specimen willchange. Thus, some change in hydraulic conducti
21、vity mayoccur when the hydraulic gradient is altered, even in caseswhere Darcys law is valid.4.4 This test method provides tools for determining flux andhydraulic conductivity values for a given GCL under thefollowing two different scenarios, which should be specified bythe requester:4.4.1 Scenario
22、1Hydrated/Saturated with Water Prior toContact with Test Liquid This scenario simulates the fieldconditions where the GCL is well hydrated with water prior tocontact with actual test liquid. It should be noted that initialdegree of saturation/hydration greatly affects the hydraulicproperties of a GC
23、L product. The test has two phases: (Phase1) hydrate, saturate, consolidate and permeate with water asTest Liquid 1, and (Phase 2) switch to permeation with testliquid as Test Liquid 2.4.4.2 Scenario 2Hydrated/Saturated with Test Liquid(Worst Case)This scenario simulates the field conditionswhere th
24、e GCL is in contact with test liquid prior to being fullyhydrated with water. It should be noted that this scenario mayresult in higher flux and hydraulic conductivity values com-pared to Scenario 1 as chemicals present in test liquid may alterthe hydration and hydraulic properties of a GCL product.
25、4.5 The apparatus used in this test method is commonlyused to determine the hydraulic conductivity of soil specimens.However, flux values measured in this test are typically muchlower than those commonly measured for most natural soils. Itis essential that the leakage rate of the apparatus in this t
26、est beless than 10 % of the flux.5. Apparatus5.1 CompatibilityAll parts in contact with the test liq-uid(s) shall be checked/verified for long-term compatibility.This can be established either based on the available informa-tion or by in-house testing.5.2 Hydraulic SystemConstant head (Method A), fa
27、llinghead (Methods B and C), or constant rate of flow (Method D)systems may be utilized provided they meet the criteriaoutlined as follows:5.2.1 Constant Head (Method A)The system must becapable of maintaining constant hydraulic pressures to within65 % and shall include means to measure the hydrauli
28、cpressures to within the prescribed tolerance. In addition, thehead loss across the tests specimen must be held constant towithin 65 % and shall be measured with the same accuracy orbetter. Pressures shall be measured by a pressure gage, elec-tronic pressure transducer, or any other device of suitab
29、leaccuracy.5.2.2 Falling Head (Methods B and C)The system shallallow for measurement of the applied head loss, thus hydraulicgradient, to within 65 %. In addition, the ratio of initial headloss divided by final head loss over an interval of time shall bemeasured such that this computed ratio is accu
30、rate to within65 %. The head loss shall be measured with a pressure gage,electronic pressure transducer, engineers scale, graduatedpipette, or any other device of suitable accuracy. Falling headtests may be performed with either a falling headwater andconstant tailwater elevation (Method B) or a fal
31、ling headwaterand rising tailwater elevation (Method C).5.2.3 Constant Rate of Flow (Method D)The system mustbe capable of maintaining a constant rate of flow through thespecimen to within +5 %. Flow measurement shall be bycalibrated syringe, graduated pipette, or other device of suit-able accuracy.
32、 The head loss across the specimen shall bemeasured to an accuracy of 5 % or better using an electronicpressure transducer or other device of suitable accuracy. Moreinformation on testing with a constant rate of flow is given inthe literature.45.2.4 System De-airingThe hydraulic system shall bedesig
33、ned to facilitate rapid and complete removal of free airbubbles from flow lines.5.2.5 Back Pressure SystemThe hydraulic system shallhave the capability to apply back-pressure to the specimen tofacilitate saturation. The system shall be capable of maintain-ing the applied back-pressure throughout the
34、 duration ofhydraulic conductivity measurements. The back-pressure sys-tem shall be capable of applying, controlling, and measuring3Olson, R. E. and Daniel, D. E., “Measurement of the Hydraulic Conductivity ofFine-Grained Soils,” Symposium on Permeability and Groundwater ContaminantTransport, ASTM S
35、TP 746, ASTM, 1981, pp. 1864.4Olson, H. W., Morin, R. H., and Nichols, R. W., “Flow Pump Applications inTriaxial Testing,” Symposium on Advanced Triaxial Testing of Soil and Rock,ASTMSTP 977, ASTM, 1988, pp. 6881.D 6766 06a2the back-pressure to 5 % or better of the applied pressure. Theback-pressure
36、 may be provided by a compressed gas supply(see Note 1), a deadweight acting on a piston, or any othermethod capable of applying and controlling the back-pressureto the tolerance prescribed in this paragraph.NOTE 1Application of gas pressure directly to a fluid will dissolvegas in the fluid. Any sui
37、table technique, including separation of gas andliquid phases with a bladder, may be used to minimize dissolution of gasin the back-pressure fluid.5.3 Flow Measurement SystemBoth inflow and outflowvolumes shall be measured unless the lack of leakage, conti-nuity of flow, and cessation of consolidati
38、on or swelling can beverified by other means. Flow volumes shall be measured by agraduated accumulator, graduated pipette, vertical standpipe inconjunction with an electronic pressure transducer, or othervolume-measuring device of suitable accuracy.5.3.1 Flow AccuracyRequired accuracy for the quanti
39、tyof flow measured over an interval of time is 65%.5.3.2 De-airing and Compliance of the SystemThe flow-measurement system shall contain a minimum of dead spaceand be capable of complete and rapid de-airing. Compliance ofthe system in response to changes in pressure shall beminimized by using a stif
40、f flow measurement system. Rigidtubing, such as metallic or rigid thermoplastic tubing, shall beused.5.3.3 Head LossesHead losses in the tubes, valves, po-rous end pieces, and filter paper may lead to error. To guardagainst such errors, the permeameter shall be assembled withno specimen inside and t
41、hen the hydraulic system filled. If aconstant or falling head test is to be used, the hydraulicpressures or heads that will be used in testing a specimen shallbe applied, and the rate of flow measured with an accuracy of5 % or better. This rate of flow shall be at least ten times greaterthan the rat
42、e of flow that is measured when a GCL specimen isplaced inside the permeameter and the same hydraulic pres-sures or heads are applied. If a constant rate of flow test is tobe used, the rate of flow to be used in testing a specimen shallbe supplied to the permeameter and the head loss measured.The he
43、ad loss without a specimen shall be less than 0.1 timesthe head loss when a GCL specimen is present.5.4 Permeant Interface Device (Bladder Accumulator)Apermeant interface device shall be used when a hazardous/corrosive or volatile test liquid, or both, is to be used as thepermeant. The permeant inte
44、rface device shall contain the testliquid in a closed chamber and allow neither possible contami-nation of flow measurement and pressure systems nor potentialrelease of chemicals present in the test liquid to the breathingair, while maintaining the desired test pressures. A schematicdiagram of a typ
45、ical permeant interface device is shown in Fig.1. The device consist of mainly a water chamber and a testliquid chamber, which are separated with a flexible bladdermembrane. The device should be checked for leaks at thedesired test pressures prior to the testing.5.5 Permeameter Cell-Pressure SystemT
46、he system forpressurizing the permeameter cell shall be capable of applyingand controlling the cell-pressure to within 65 % of the appliedFIG. 1 Schematic Diagram of Permeant Interface DeviceD 6766 06a3pressure. However, the effective stress on the test specimen(which is the difference between the c
47、ell-pressure and the porewater pressure) shall be maintained to the desired value with anaccuracy of 65 % or better. The device for pressurizing the cellmay consist of a reservoir connected to the permeameter celland partially filled with de-aired water, with the upper part ofthe reservoir connected
48、 to a compressed gas supply or othersource of pressure (see Note 2). The gas pressure shall becontrolled by a pressure regulator and measured by a pressuregage, electronic pressure transducer, or any other devicecapable of measuring to the prescribed tolerance. A hydraulicsystem pressurized by dead-
49、weight acting on a piston or anyother pressure device capable of applying and controlling thepermeameter cell-pressure to the tolerance prescribed in thisparagraph may be used.NOTE 2De-aired water is commonly used for the cell fluid tominimize potential for diffusion of air through the membrane into thespecimen. Other fluids, such as oils, which have low gas solubility are alsoacceptable, provided they do not react with components of the permeame-ter. Also, use of a long (approximately 5 to 7 m) tube connecting thepressurized cell liquid
