ASTM_D_6918_-_09_2022.pdf

Designation:D691809(Reapproved 2022)Standard Test Method forTesting Vertical Strip Drains in the Crimped Condition1This standard is issued under the fixed designation D6918;the number immediately following the designation indicates the year oforiginal 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 is a performance test that measures theeffect crimping has on the ability of vertical strip drains totransmit water parallel to the plane of the drain.1.2 This test method is applicable to all vertical strip drains.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 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 Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products(RECPs)for TestingD4439 Terminology for Geosynthetics3.Terminology3.1 Definitions:3.1.1 For general geosynthetics terms used in this testmethod,refer to Terminology D4439.3.2 Definitions of Terms Specific to This Standard:3.2.1 vertical strip drain,na geocomposite consisting of ageotextile cover and drainage core installed vertically into soilto provide drainage for accelerated consolidation of soils.4.Summary of Test Method4.1 This test method presents two methods for determiningthe effect of a crimp forming in the vertical strip drain due tothe consolidation of soils around it in the field.4.1.1 A vertical strip drain is sealed in a waterproof mem-brane to prevent any water from escaping out through thegeotextile during the test.4.1.2 The sealed vertical strip drain is placed in the appro-priate crimping device and water is allowed to pass through itunder a constant head of water.4.1.3 A crimp is placed on the specimen,and water allowedto pass through it under a constant head in the crimpedcondition.4.1.4 The flow rate of water along the plane of the un-crimped vertical strip drain is compared to the flow rate in thecrimped condition.5.Significance and Use5.1 This test method is considered satisfactory for theacceptance of commercial shipments of vertical strip drains.5.1.1 In case of dispute arising from differences in reportedtest results when using this test method for acceptance testingof commercial shipments,the purchaser and the suppliershould conduct comparative tests to determine if there is anystatistical bias between their laboratories.Competent statisticalassistance is recommended for the investigation of bias.As aminimum,the two parties should take a group of test speci-mens that as homogenous as possible,and that are from a lot ofmaterial of the type in question.The test specimens should berandomly assigned in numbers to each laboratory for testing.The average results from the two laboratories should becompared using Students t-test for unpaired data and anacceptable probability level chosen by the two parties beforethe start of testing.If a bias is found,either its cause must befound and corrected,or the purchaser and the supplier mustagree to interpret future test results in light of the known bias.5.2 Vertical strip drains are installed in areas where it isdesired to increase the rate of soil consolidation.It has beenshown that as the soil around the vertical strip drainconsolidates,a crimp may form in the vertical strip drain dueto the movement of the drain in the area of soil consolidation.5.3 This test method can be used to evaluate if there is anyreduction in flow rate of water through the drain due to the1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.03 on Perme-ability and Filtration.Current edition approved Aug.1,2022.Published August 2022.Originallyapproved in 2003.Last previous edition approved in 2014 as D6918 09(2014).DOI:10.1520/D6918-09R22.2For 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 standards Document Summary page onthe ASTM website.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 r