1、Designation: D 6918 03 (Reapproved 2007)Standard Test Method forTesting Vertical Strip Drains in the Crimped Condition1This standard is issued under the fixed designation D 6918; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、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 is a performance test, which measuresthe effect crimping, has on the ability of vertical str
3、ip 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 as thestandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use.
4、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 4354 Practice for Sampling of Geosynthetics for Testing3. Terminology3.1 Def
5、initions:3.1.1 geocomposite, na product composed of two or morematerials, at least one of which is a geosynthetic.3.1.2 geosynthetics, na planar product manufactured frompolymeric materials used with soil, rock, earth, or othergeotechnical engineering related material as an integral part ofa man-mad
6、e project, structure, or system.3.1.3 geotextile, na permeable geosynthetic comprisedsolely of textiles.3.1.3.1 DiscussionGeotextiles perform several functionsin geotechnical engineering applications, including: separation,filtration, drainage, reinforcement, and protection.3.1.4 vertical strip drai
7、n, 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 describes procedures for determiningthe effect of a crimp forming in the vertical strip drain du
8、e theconsolidation of soils around it in the field.4.1.1 Avertical strip drain is sealed in a cover of heat shrinkplastic to prevent any water from escaping out through thegeotextile during the test.4.1.2 The sealed vertical strip drain is placed in the crimpingdevice (See Fig. 1) and water is allow
9、ed to pass through itunder a constant head of water.4.1.3 A 90 crimp is placed on the specimen, and waterallowed to 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 thecri
10、mped 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
11、, 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 homogeno
12、us 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 lev
13、el 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.1This test method is under the jurisdiction of ASTM Committee D35 onGeosyn
14、thetics and is the direct responsibility of Subcommittee D35.03 on Perme-ability and Filtration.Current edition approved June 1, 2007. Published July 2007. Originally approvedin 2003. Last previous edition approved in 2003 as D 691803.2For referenced ASTM standards, visit the ASTM website, www.astm.
15、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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 Vertica
16、l 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 drain consoli-dates, a crimp may form in the vertical strip drain due to themovement of the drain in the area of soil consolidation.5.3 Thi
17、s test method can be used to evaluate if there is anyreduction in flow rate of water through the drain due to thecrimping, and what effect, if any, this crimping may have onthe rate of consolidation of the soil.6. Apparatus6.1 The test device must be capable of maintaining aconstant head of water on
18、 the vertical strip drain being tested.The apparatus consists of a water chamber assembly, a speci-men holder, and a crimping wedge, all of which are attached toa holding stand. See Fig. 2.6.2 Container, for collecting the water as it flows throughthe vertical strip drain.6.3 Stopwatch or Electronic
19、 Timing Device, connected tothe collection container, for timing the flow of water throughthe vertical strip drain.6.4 Blow Dryer, used for applying heat to the heat shrink-wrap that is placed around the test specimen prior to testing.7. Materials7.1 Heat Shrink Plastic WrapThe heat shrink plasticwr
20、ap, of the type used in homes for sealing windows fromwind drafts, is used to seal the vertical strip drain so that waterdoes not flow out through the geotextile wrap on the core. Thewater is to flow in a parallel plan to the fabric, along the corematerial of the drain.7.2 Bathtub Caulkthe caulk is
21、used to seal the testspecimen into the water chamber assembly as directed in 12.2.8. Hazards8.1 There are no known hazards either with the materials, orin performing this test.9. Sampling, Test Specimens, and Test Units9.1 Division into Lots and Lot SamplesDivide the mate-rial into lots and take a l
22、ot sample as directed in PracticeD 4354. Rolls of prefabricated vertical strip drains are theprimary sampling unit.9.2 Laboratory SampleRemove the outer wrap of drainmaterial from the roll to avoid sampling and testing anymaterial, which may have been damaged during storage. Takefor the laboratory s
23、ample a 1830 mm (6 ft) length of the drainmaterial.9.3 Test SpecimensFrom the laboratory sample takenfrom each lot, cut test specimens as directed in 10. Each testspecimen shall be 610 mm (2 ft) long.10. Number of Specimens10.1 Unless otherwise agreed upon, as when provided in anapplicable material
24、specification, take a number of test speci-mens per laboratory sample such that the user may expect the95 % probability level that the test result is no more than 5 %above the average for each laboratory sample.10.1.1 Reliable Estimate of vWhen there is a reliableestimate of v based upon extensive t
25、est records for similarmaterials in the users laboratory as directed in the method,calculate the required number of specimens using Eq 1 asfollows:n 5 tv / A!2(1)where:n = number of test specimens, rounded upward to a wholenumber,FIG. 1 Crimping WedgeFIG. 2 Complete Crimp Test ApparatusD 6918 03 (20
26、07)2v = reliable estimate of coefficient of variation of indi-vidual observations on similar materials in the userslaboratory under single operator precision, %.t = the value of Students t for I = one sided limits, at 95 %probability level, and the degrees of freedom associ-ated with the estimate of
27、 v, andA = 5.0 % of the average, the value of the allowablevariation.10.1.2 No Reliable Estimate of vWhen there is no reliableestimate of v for the users laboratory, Eq 1 should not be useddirectly. Instead, specify the fixed number of three specimensfor testing.11. Conditioning11.1 Prior to testing
28、, the specimens shall be conditioned atthe standard atmosphere for testing geosynthetics for 24 h priorto testing. If the environment of the users laboratory is unableto be maintained at the standard atmosphere for testinggeosynthetics, the specimens shall be conditioned for 24 h inthe environment i
29、n which they will be tested.12. Procedure12.1 Specimen PreparationWrap the full length of eachspecimen with heat shrink plastic. Using the blow dryer, applyheat until the wrap has shrunk tightly around the specimens.NOTE 1The heat shrink wrap seals the geotextile so that water willnot escape through
30、 it, but rather flow parallel to the plane of the drain forthe full length of the specimen.12.2 Place the specimen through the slot in the bottom plateof the water chamber assembly. The specimen should protrudeup into the chamber 6.35 mm (0.25 in.). Seal the specimen intothe slot with easily a remov
31、able sealant, such as bathtub caulk.12.2.1 Thread the specimen down through the upper andlower level specimen holders of the test stand, and fasten thebottom plate of the water chamber assembly to the stand.Complete the assembly of the water chamber assembly.Tighten the plates of the specimen holder
32、s snuggly against thespecimen, being careful not to pinch the specimen to tight suchthat the flow of water will be effected.12.3 Fill the water chamber to the outlet of the chamber.Adjust the flow to maintain a constant head of 610 mm (24 in.)on the specimen.NOTE 2The head is measured from the water
33、 chamber outlet pipe tothe point where the water exits the drain.12.4 Take and record five flow measurements (Q in mL)over a set time interval (t) in the uncrimped condition.Generally5sisused as the time interval.12.5 Following the fifth reading in the uncrimped condition,shut off the water flow to
34、the water chamber, and allow thechamber to empty.12.5.1 Once the water chamber is empty, loosen the lowerspecimen holder. Crimp the specimen by tuning the handle ofthe crimp device until the specimen is crimped to the 90 angleof the crimper.NOTE 3Extreme care needs to be taken when crimping the spec
35、imensuch that it is not pinched.12.6 Repeat 12.3-12.5 for the crimped condition.12.7 Repeat 12.1-12.6 for the remaining specimens.13. Calculation or Interpretation of Results13.1 For each of the specimens, calculate the average flowof the five flow measurements, corrected for temperature in theuncri
36、mped condition using Eq 2.Qavg5 Q11 Q21 Q31 Q41 Q5!# RT(2)where:Qavg= average flow for each specimen corrected forviscosity at 20C,Q1-5= individual flow measurements for each specimen,andRT= temperature correction factor determined using Eq3.RT5 uT/ u20C(3)where:uT= viscosity of water at test temper
37、ature, Poiseuille,from Table 1, andu20C= viscosity of water at 20C, Poiseuille, from Table1.13.2 Calculate the corrected average flow (QT avg)oftheresults in 13.1.13.3 Calculate the corrected average flow velocity for thethree specimens in the uncrimped condition using Eq 4.Vuc5 QTavg/ t (4)where:Vu
38、c= average flow velocity in cc/sec for the uncrimpedcondition,QT avg= average flow, in cc from 13.2, andt = time interval of flow, 5 s.13.4 Repeat 13.1-13.3 for the crimped condition.13.5 Calculate the percent change in flow velocity betweenthe uncrimped and crimped condition using Eq 5u5Vuc Vcr!# /
39、 Vuc3 100 (5)where:Vuc= flow velocity in the uncrimped condition, andVcr= flow velocity in the crimped condition.14. Report14.1 The report shall include the following:TABLE 1 Water ViscosityTemperature, C Ut Poiseulle* 3 10-310 1.300711 1.271312 1.236313 1.202814 1.170915 1.140416 1.111117 1.082818
40、1.055919 1.029920 1.00521 0.98122 0.957923 0.935824 0.914225 0.8937D 6918 03 (2007)314.1.1 A statement that the specimens were tested in accor-dance with ASTM D 6918,14.1.2 A description, including brand name, and style des-ignation if appropriate, of the vertical strip drain tested,14.1.3 A stateme
41、nt that the material was sampled in accor-dance with Practice D 4354,14.1.4 Any deviations from this standard,14.1.5 The individual flow measurements of each specimen,and the time interval over which the flow was measured, inboth the uncrimped and crimped conditions,14.1.6 The water temperature at w
42、hich the test was run,14.1.7 The corrected flow values for 20C,14.1.8 The corrected average flow values for each speci-men,14.1.9 The average flow of the three specimens,14.1.10 The average flow velocity for the three specimens inthe uncrimped and crimped conditions, and14.1.11 The percent change in
43、 flow velocity between theuncrimped and crimped conditions.15. Precision and Bias15.1 PrecisionThe precision of Test Method D 6918 isbeing determined.15.2 BiasThe procedure in this test method has no knownbias because the value of that property can only be defined interms of the test method.16. Keyw
44、ords16.1 constant head; crimped; flow velocity; percent change;uncrimped; vertical strip drainASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determinat
45、ion of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withd
46、rawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your
47、 comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 6918 03 (2007)4
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