1、Designation: D8204 18Standard Practice forBurial and Retrieval of Samples in a Test Pad to EvaluateInstallation Effects on Geosynthetic Clay Liners1This standard is issued under the fixed designation D8204; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n 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 practice covers standardized procedures for obtain-ing samples of geosyntheti
3、c clay liners (GCLs) from a test padfor use in assessment of the effects immediately after installa-tion caused only by the installation techniques. The assessmentmay include physical testing. This practice is applicable toGCLs only.1.2 This practice is limited to full-scale test pads, and doesnot a
4、ddress laboratory modeling of field conditions. Thispractice does not address which test method(s) to use forquantifying installation damage.1.3 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
5、to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Pri
6、nciples for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1557 Test Methods for Laboratory Compaction Character-istics of Soil Using Modified Effort
7、(56,000 ft-lbf/ft3(2,700 kN-m/m3)D1883 Test Method for California Bearing Ratio (CBR) ofLaboratory-Compacted SoilsD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD2487 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classi
8、fication System)D4429 Test Method for CBR (California Bearing Ratio) ofSoils in Place (Withdrawn 2018)3D4439 Terminology for GeosyntheticsD5887/D5887M Test Method for Measurement of IndexFlux Through Saturated Geosynthetic Clay Liner Speci-mens Using a Flexible Wall PermeameterD5888 Guide for Storag
9、e and Handling of GeosyntheticClay LinersD5993 Test Method for Measuring Mass per Unit Area ofGeosynthetic Clay LinersD6072/D6072M Practice for Obtaining Samples of Geosyn-thetic Clay LinersD6102 Guide for Installation of Geosynthetic Clay LinersD6496/D6496M Test Method for Determining AverageBondin
10、g Peel Strength Between Top and Bottom Layersof Needle-Punched Geosynthetic Clay LinersD6768/D6768M Test Method for Tensile Strength of Geo-synthetic Clay LinersD6913/D6913M Test Methods for Particle-Size Distribution(Gradation) of Soils Using Sieve Analysis2.2 GRI Standard:4GRI Guide GS11 Standard
11、Guide for Constructing Test Padsto Assess Protection Materials Intended to AvoidGeomembrane Puncture3. Terminology3.1 Definitions:3.1.1 geosynthetic clay liner (GCL), na manufacturedhydraulic barrier consisting of clay bonded to a layer or layersof geosynthetics.3.1.2 multi-component GCL, nGCL with
12、an attached film,coating, or membrane decreasing the hydraulic conductivity orprotecting the clay core, or both.3.1.3 sample, n(1) a portion of material that is taken fortesting or for record purposes; (2) a group of specimens used,1This practice is under the jurisdiction of ASTM Committee D35 on Ge
13、osyn-thetics and is the direct responsibility of Subcommittee D35.04 on GeosyntheticClay Liners.Current edition approved July 15, 2018. Published July 2018. Originallyapproved in 2018. DOI: 10.1520/D8204-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer
14、 Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from Geosynthetic Institute, 475 Kedron Avenue, Folsom, PA1
15、9033-1208, http:/www.geosynthetic-institute.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the De
16、cision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1or of observations made, which provide information that can beused for making statistical inferences about the population
17、(s)from which the specimens are drawn.3.1.4 test pad, na distinct area of actual or simulatedfull-scale construction.3.2 For definitions of other geosynthetics terms used in thispractice, refer to Terminology D4439.4. Summary of Practice4.1 Damage to geosynthetic clay liners (GCLs) from instal-latio
18、n operations may be quantified by evaluating specimensfrom a sample(s) exhumed from a full-scale installation. Thesample(s) should be installed using project-specific proceduresand materials. When project-specific materials or procedures(or both) are unknown, generally accepted, representativemateri
19、als and procedures should be used and thoroughlydocumented and reported. Addressed within this practice are:amount of GCL sample(s) to install; procedures for installingthe GCL sample(s); procedures for exhuming the GCLsample(s); procedure for obtaining control sample(s); andreport preparation guide
20、lines. The sample(s) should be re-trieved immediately after installation to minimize potentialaging of the GCL. Comparison of test results on exhumed andcontrol specimens may be used to assess effects of installation.Tests to perform are not addressed herein, and will vary withthe type and function
21、of geosynthetic and project requirements.5. Significance and Use5.1 The ability to maintain design function (for example,barrier) or design properties (for example, peel strength,chemical resistance, etc.), or both, of a geosynthetic clay linermay be affected by damage to the physical structure of t
22、heGCLdue to the rigors of field installation. The effect of damagemay be assessed by analyzing specimens cut from sample(s)retrieved after installation in a representative test pad. Analysismay be performed with visual examination or laboratorytesting of specimens from the control sample(s), and fro
23、m theexhumed sample(s).5.2 A uniform practice for installing and retrieving repre-sentative sample(s) from a test pad is needed to assessinstallation damage using project-specific or generallyaccepted, representative materials and procedures. Damage ofa specific grade and type of GCL under specific
24、installationprocedures may be assessed with sample(s) exhumed from afull-scale test pad.6. Procedure6.1 ObjectiveGeosynthetic clay liner and soil placementtechniques shall model the methods anticipated duringconstruction, but may also be designed to model hypotheticalconditions such as various degre
25、es of compaction, lift heights,drop heights, equipment operations, types of fill material, orcombinations thereof.6.2 Test Pad Configurations:6.2.1 The test pad configuration is an importantconsideration, and Fig. 1 is crafted so as to present several ofthe various options. In this regard, test pads
26、 are either above orbelow the ground surface and used either for specific designconfirmation or to investigate various stone thicknesses.Typically, test pads are designed with soil coverage on top(6.3.1 6.3.4).6.2.2 Lateral confinement of the cover soil should beconsidered during the compaction of t
27、he soils to simulaterealistic site conditions.6.3 The four test pad configurations shown in Fig. 1(adapted from GRI Guide GS11) are described in 6.3.1 6.3.4and could utilize various different GCL barrier systems (forexample, GCL alone, multi-component GCL, GCL withgeotextile, GCL with geomembrane, G
28、CL with geosyntheticdrainage layer, etc.).6.3.1 Above Ground with Uniform Cover Soil Thickness:6.3.1.1 This cross section is meant to confirm a givendesign, including the intended GCL barrier system, soil type,and soil thickness.6.3.2 Above Ground with Variable Soil Thickness:6.3.2.1 This investigat
29、ive type cross section is meant todiscover what minimum stone thickness is necessary to avoidpuncture to the underlying GCL barrier system. The GCLsystem is held constant along with the soil type, but not itsthickness.6.3.3 Below Ground with Uniform Soil Thickness:6.3.3.1 Unlike in the above-ground
30、configuration, the coversoil in this cross section is restrained from lateral movement bythe surrounding soil.6.3.4 Below Ground with Variable Soil Thickness:6.3.4.1 This cross section is used to discover what minimumstone thickness is necessary to avoid puncture to the underlyingGCL. Unlike the abo
31、ve-ground configuration, however, thestone will be laterally confined, which is an advantage for thicklayers of stone.6.3.5 GCL Without Cover Soil:6.3.5.1 GCL test pads can be constructed without additionalcover soil, that is, only being covered by a geomembrane, toinvestigate moisture uptake, desic
32、cation, panel separation, etc.Other test methods, as mentioned in 7.1, and testing proceduresmight be needed to be specified.FIG. 1 Design of Test Pad Cross SectionsD8204 1826.3.5.2 GCL test pads can be constructed without cover soilto demonstrate that vehicles can drive over the GCL, if needed,to i
33、nstall other geosynthetic materials (Guide D6102 mentionsthat low ground pressure vehicles such as four-wheeled all-terrain vehicles may be suitable) such as geomembranes,geosynthetic drainage systems, geotextiles, geogrids, or othergeosynthetic materials.6.4 The type of soil or rock (or both) of th
34、e foundationmaterial upon which the GCL is placed is a critical item. Ifstones (or rock) are present, the GCL can likely be puncturedfrom below. It might be necessary to place an additionalprotection geotextile beneath the GCL. If this is not the intent,then a proper foundation material must be agre
35、ed upon by theparties involved.6.5 The type(s) of traffic loading/repetitions is anothercritical item, and must be agreed upon by the various partiesinvolved.6.6 Size of Test Pad:6.6.1 The width of the test pad should be at least 100 %greater than the width of the agreed-upon placement andcompaction
36、 equipment or the trafficking equipment for the twoabove-ground options and 50 % greater for the two below-ground options. In this regard, the confinement by natural soilis an advantage. Other advantages are that equipment will nothave to ramp up or ramp down from an elevated test pad placedon the o
37、riginal ground surface, as well as the associated safetyconsiderations.6.6.2 The length of the test pad should be 300 % greaterthan the length of the agreed-upon placement and compactionequipment for the constant-thickness option, and from five toten times greater for the variable-thickness options.
38、NOTE 1The test pad length might need to be longer than theabove-stated values, depending on the degree of accuracy required toobtain the critical soil thickness for the variable thickness option(s).6.7 Installation Procedure:6.7.1 The soil subgrade or initial lift on which the geosyn-thetic clay lin
39、er will be placed shall be constructed to specifiedconditions of soil type, moisture content, and compaction. Inthe case that the GCL is placed over another geosynthetic, thegeosynthetic shall be recorded and be installed to thegeosynthetic-specified conditions.NOTE 2In certain situations, it may be
40、 a requirement that the bentoniteof the GCL pre-hydrates prior to further traffic over the GCL. In this case,the pre-hydration period of the bentonite with the water from the subsoilshould be specified and recorded. Construction equipment used for furtherplacement of cover materials should be the sa
41、me as will be used toconstruct overlying lifts, unless otherwise requested. The GCL should beinstalled in accordance with project-specific procedures. When project-specific procedures or materials (or both) are not known, representativeequipment, materials, and procedures should be used and thorough
42、lydocumented. This applies to 6.7.2 6.7.8 as well.6.7.2 Note, if requested, the subgrade parameters (PracticeD2487) such as particle size gradations (Test Methods D6913/D6913M), moisture content (Test Methods D2216), layerthickness, determination of Atterberg limits, Proctor density,field density of
43、 soil, CBR of soil in the field (Test MethodD4429), CBR of soil in the laboratory (Test Method D1883), orother relevant parameters, geometry, and other conditions, orcombinations thereof.6.7.3 The material to be placed above the GCL underinvestigation will typically be a soil fill, or another geosyn
44、-thetic material(s) with soil then placed upon it. When project-specific procedures or materials (or both) are not known,representative equipment, materials, and procedures should beused and thoroughly documented.NOTE 3In certain situations, such as multiple-layer installations,movement of individua
45、l layers in test pads may occur. Care should betaken to ensure that stress and potential slippage conditions in the test padssimulate actual field conditions as closely as possible.6.7.4 Fill placement above the GCL shall model expectedfield conditions. Construction equipment used in fill placements
46、hould be the same as that to be used in subsequent construc-tion of the earth structure. Equipment shall be operated inaccordance with project-specific procedures. When project-specific equipment, procedures, materials, or combinationsthereof are not known, representative equipment, materials,and pr
47、ocedures should be used and thoroughly documented.6.7.5 Spread fill into lifts above the GCL modeling expectedfield conditions. Construction equipment used in fill spreadingshould be in accordance with project-specific procedures.When project-specific equipment, procedures, materials, orcombinations
48、 thereof are not known, representative equipment,materials, and procedures should be used and thoroughlydocumented.6.7.6 Fill lift compaction above the GCL shall modelexpected field conditions. Construction equipment used in soilcompaction should be in accordance with project specifica-tions. When p
49、roject-specific equipment, procedures, materials,or combinations thereof are not known, representativeequipment, materials, and procedures should be used andthoroughly documented.NOTE 4Commonly used procedures include the following: 300-mmsoil lifts compacted to 90 % Modified Proctor density (Test MethodsD1557) using a minimum 4500-kg (total) vibratory steel roll (single ortandem). Typical soils/aggregates include coarse gravel (GP, d50 20mm), concrete sand (SW d50 1.0 mm), or silty sand (SM d50 0.4 mm).NOTE 5Following placement and compaction for the lift, procedure
