1、Designation:D4491/D4491M22Standard Test Methods forWater Permeability of Geotextiles by Permittivity1This standard is issued under the fixed designation D4491/D4491M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last re
2、vision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 These test methods cover procedures for deter
3、miningthe hydraulic conductivity(water permeability)of geotextilesin terms of permittivity under standard testing conditions,inthe uncompressed state.Included are three procedures:theconstant head and falling head methods using a water flowapparatus,and the air flow method using an air flow apparatu
4、s.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system are not necessarily exact equivalents;therefore,toensure conformance with the standard,each system shall beused independently of the other,and values from the twosy
5、stems shall not be combined.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 to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory l
6、imitations 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 Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organizati
7、on TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD653 Terminology Relating to Soil,Rock,and ContainedFluidsD4439 Terminology for GeosyntheticsD5199 Test Method for Measuring the Nominal Thicknessof GeosyntheticsE691 Practice f
8、or Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ASTM Adjuncts:3Detailed Drawings and Materials List for Construction,10Drawings3.Terminology3.1 Definitions:3.1.1 geotextile,na permeable geosynthetic comprisedsolely of textiles.3.1.2 permeability,nthe rate of flow
9、 of a liquid under adifferential pressure through a material.3.1.2.1 DiscussionThe nominal thickness is used as it isdifficult to evaluate the pressure on the geotextile during thetest,thereby making it difficult to determine the thickness ofthe fabric under these test conditions.3.1.3 permeability,
10、nof geotextiles,hydraulic conductiv-ity.3.1.4 permittivity,(),(T1),nof geotextiles,the volu-metric flow rate of water per unit cross-sectional area per unithead under laminar flow conditions,in the normal directionthrough a geotextile.3.1.5 For the definitions of other terms relating togeotextiles,r
11、efer to Terminology D4439.For the definitions oftextile terms,refer to Terminology D123.For the definition ofcoefficient of permeability,refer to Terminology D653.4.Summary of Test Method4.1 Water Flow Test MethodsThese test methods describeprocedures for determining the permittivity of geotextiles
12、usingconstant head or falling head test procedures with a water flowapparatus:4.1.1 Method A Constant Head TestA head of 50 mm ofwater is maintained on the geotextile throughout the test.Thequantity of flow is measured versus time.The constant headtest is used when the flow rate of water through the
13、 geotextileis so large that it is difficult to obtain readings of head change1These test methods are under the jurisdiction of ASTM Committee D35 onGeosynthetics and are the direct responsibility of Subcommittee D35.03 onPermeability and Filtration.Current edition approved May 1,2022.Published June
14、2022.Originallyapproved in 1985.Last previous edition approved in 2021 as D4491/D4491M 21.DOI:10.1520/D4491_D4491M-22.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the
15、 standards Document Summary page onthe ASTM website.3Detailed drawings and a materials list for construction are available fromASTM International Headquarters.Order Adjunct No.ADJD4491.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis in
16、ternational standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1versus time in the falling head test.The constant head test is thereferee method for this standard.NOTE1Data has shown agreement between the falling and constanthead methods of determining per
