1、Designation: D 4647 061Standard Test Method forIdentification and Classification of Dispersive Clay Soils bythe Pinhole Test1This standard is issued under the fixed designation D 4647; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, 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.1NOTESection 10.1.14 was editorially corrected in September 2009.1. Scope*1.1 This test method presents a direct, qu
3、alitative measure-ment of the dispersibility and consequent colloidal erodibilityof clay soils by causing water to flow through a small holepunched in a specimen. This test method is complemented byTest Method D 4221.1.2 This test method and the criteria for evaluating test dataare based upon result
4、s of several hundred tests on samplescollected from embankments, channels, and other areas whereclay soils have eroded or resisted erosion in nature (1).21.3 Three alternative procedures for classifying the dispers-ibility of clay soils are provided as follows:1.3.1 Method A and Method C, adapted fr
5、om Ref (1),classify soils into six categories of dispersiveness as: dispers-ibility (D1, D2), slight to moderately dispersive (ND4, ND3),and nondispersive (ND2, ND1).1.3.2 Method B classifies soils into three categories ofdispersiveness as: dispersibility (D), slightly dispersive (SD),and nondispers
6、ive (ND).1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are provided forinformation only.1.5 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 standar
7、d 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:3D 422 Test Method for Particle-Size Analysis of SoilsD 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 698 Test Meth
8、ods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12 400 ft-lbf/ft3(600kN-m/m3)D 1193 Specification for Reagent WaterD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 2487 Practice for Classification of Soils for Engin
9、eeringPurposes (Unified Soil Classification System)D 2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D 3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD 4221 Test M
10、ethod for Dispersive Characteristics of ClaySoil by Double HydrometerD 4318 Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of SoilsD 4753 Guide for Evaluating, Selecting, and SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD 6026 Prac
11、tice for Using Significant Digits in Geotechni-cal Data3. Terminology3.1 Definitions:3.1.1 For definitions of terms in this test method, refer toTerminology D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 dispersive claysclays that diaggregate easily andrapidly in water of low-salt co
12、ncentration, and without signifi-cant mechanical assistance. Such clays usually have a highproportion of their adsorptive capacity saturated with sodiumcations.3.2.1.1 DiscussionSuch clays generally have a highshrink-swell potential, have low resistance to erosion, and havelow permeability in an int
13、act state.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.06 on Physical-ChemicalInteractions of Soil and Rock.Current edition approved Nov. 1, 2006. Published December 2006. Originallyapproved in 1987. Last previo
14、us edition approved in 1998 as D 4647 93(2006).2The boldface numbers in parentheses refer to the list of references at the end ofthis test method.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards
15、 volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Test Method4.1 The t
16、est method is started with distilled water flowinghorizontally under a hydraulic head of 50 mm (2 in.) througha 1.0-mm (0.04-in.) diameter hole punched in the soil speci-men. The nature of the solution emerging from the specimenunder the intial 50-mm (2-in.) head provides the principledifferentiatio
17、n between dispersive and nondispersive clays.Flow from dispersive clays will be distinctly dark and the holethrough the specimen will enlarge rapidly, with a resultantincrease in the flow rate. Flow from slightly to moderatelydispersive clays will be slightly dark with a constant hole sizeand flow r
18、ate. Flow from nondispersive clays will be com-pletely clear with no measurable increase in the hole size.4.2 Test results are evaluated from the appearance of theflowing solution emerging from the specimen, the rate of flow,and the final size of the hole through the specimen. Theseobservations prov
19、ide the basis for classifying the soil speci-men.5. Significance and Use5.1 The pinhole test provides one method of identifying thedispersive characteristics of clay soils that are to be or havebeen used in earth construction. The piping failures of anumber of homogeneous earth dams, erosion along c
20、hannel orcanal banks, and rainfall erosion of earthen structures havebeen attributed to the colloidal erosion along cracks or otherflow channels formed in masses of dispersive clay (2).5.2 This test method models the action of water flowingalong a crack in an earth embankment. Other indirect tests,s
21、uch as the double hydrometer test (Test Method D 4221), thecrumb test (3, 4), that relates the turbidity of a cloud ofsuspended clay colloids as an indicator of the clay dispersivity,and chemical tests that relate the percentage of sodium to totalsoluble salt content of the soil are also used as ind
22、icator testsof clay dispersibility (2). The comparison of results from thepinhole test and other indirect tests on hundreds of samplesindicates that the results of the pinhole test have the bestcorrelation with the erosional performance of clay soils innature.5.3 Method A and Method C of the pinhole
23、 test require theevaluation of cloudiness of effluent, final size of the pinhole,and computation of flow rates through the pinhole in order toclassify the dispersive characteristics of the soil. Method Brequires only the evaluation of the cloudiness of effluent andfinal size of the pinhole to classi
24、fy the dispersive characteristicsof the soil. The computation of flow rates through the pinholein Method A serves primarily as a guide to the properequipment and specimen performance under sequential pres-sures applied during the test. All methods produce similarresults and any method can be used to
25、 identify dispersive clays.5.4 The use of Method A or Method C results in theaccumulation of data relative to sequential flow rates throughthe pinhole and consequent enlargement or erosion of the hole.The pinhole erosion test was developed for the purpose ofidentifying dispersive soils and is not in
26、tended to be ageometrically scaled model of a prototype structure. Since thetheory of similitude was not used in the design of the pinholetest, quantitative data are not obtained. The quantity of flowthrough the pinhole, amount of soil erosion, or the rate of soilerosion should not be extrapolated t
27、o actual field conditions(3). However, such data may be useful in performing qualita-tive evaluations of the consequences of such erosion in termsof dam failure, loss of life and property. They also may be usedin considering the cost effectiveness of defensive designmeasures necessary to minimize th
28、e effects of failure due todispersive clays. For example, the amount of colloidal erosionthat will occur in a soil classed as ND2 (very slightlydispersive) will be very small for a relatively long period oftime. Such erosion may not be significant in evaluating thecost-benefit relationships in proje
29、cts where public safety is notinvolved or where normal maintenance procedures will handlethe problem. In such cases, classifying the soil as ND (nondis-persive) using Method B of the pinhole test should beadequate.5.5 Pinhole tests that result in classifying soil as slightlydispersive (ND3 by Method
30、 A or Method C or SD by MethodB) indicate high uncertainty about the existence of significantproblems to be considered in the design or stability of astructure. In such cases, it is advisable to resample and test anumber of other soils from the same area to generate anadequate statistical sample for
31、 problem evaluation. The origi-nal slightly dispersive sample may come from an area on theedge of a more highly dispersive soil.5.6 In a few physiographic areas or geoclimatic conditions,or both, neither the pinhole test nor the other indicator testsprovide consistent identification of dispersive cl
32、ays (5, 6, 7).Insuch cases, the results of the tests (8, 9) should be evaluated interms of cost effectiveness and design judgment (7).5.7 For some projects, it may be desirable to perform thepinhole test using eroding fluids other than distilled water (8,10). In such cases, Method A, Method B, or Me
33、thod C may beused to identify the dispersive characteristics of the soil andcompare the results with those obtained using distilled water.NOTE 1Notwithstanding the statement on precision and bias con-tained in this test method: The precision of this test method is dependenton the competence of the p
34、ersonnel performing it, and the suitability of theequipment and facilities used.Agencies which meet the criteria of PracticeD 3740 are generally considered capable of competent and objectivetesting. Users of this test method are cautioned that compliance withPractice D 3740 does not in itself assure
35、 reliable testing. Reliable testingdepends on several factors; Practice D 3740 provides a means of evalu-ating some of those factors.6. Limitations6.1 Development of the test procedure to provide reproduc-ible results that differentiate between clay soils that wereknown to be erodible (dispersive) a
36、nd nonerodible (nondisper-sive) in the field indicates the following limitations in the useof this test:6.1.1 This test method is not applicable to soils with lessthan 12 % fraction finer than 0.005 mm and with a plasticityindex less than or equal to 4 (2, 11). Such soils generally havelow resistanc
37、e to erosion regardless of dispersive characteris-tics.6.1.2 The most consistent results are produced when thenatural water content of the sample is preserved during thesampling, shipping, storage, and testing operations.D 4647 06126.1.3 A few instances have been reported in which thepinhole test di
38、d not identify some dispersive clays in which thepore water contained less than 0.4 meq/L total soluble salts thatwere more than 80 % sodium salts.6.1.4 This test method was developed to test specimens ofdisturbed soil that are compacted into the test cylinder. This testmethod can also be used to te
39、st undisturbed specimens whenthey are properly trimmed and sealed into the test cylinder;however, some investigators (6) have found that this testmethod is not applicable in evaluating the dispersive charac-teristics of undisturbed specimens of highly sensitive clays.Such clays may be classed as dis
40、persive from the pinhole testresults but perform as nondispersive materials in nature.6.1.5 This test method is performed with distilled water, ata pH of 5.5 to 7.0, as the eroding fluid. The use of water withvarious ionic concentrations and combinations will alter theresults of the test (8, 10).7.
41、Classification7.1 The observations of this test method provide the basisfor classifying the soil specimen into a category of dispersive-ness according to the following general criteria:7.1.1 Method A:D1, D2Dispersive clays that fail rapidly under 50-mm(2-in.) head.ND4, ND3Slightly to moderately disp
42、ersive clays thaterode slowly under 50-mm (2-in.) or 180-mm (7-in.) head.ND2, ND1Nondispersive clay with very slight to nocolloidal erosion under 380-mm (15-in.) or 1020-mm (40-in.)head.7.1.2 Method B:DDispersive clays that erode rapidly under 50-mm (2-in.)head.SDSlightly dispersive clays that erode
43、 slowly under180-mm (7-in.) head.NDNondispersive clays that show very slight or nocolloidal erosion under 380-mm (15-in.) head.NOTE 2Method B for classifying dispersiveness of clay soils com-bines the categories of Method A as follows: D = D1, D2, ND4;SD = ND3; and ND = ND2, ND1.7.1.3 Method C:D1, D
44、2Dispersive clays that fail rapidly under 50-mm(2-in.) head.ND4, ND3Dispersive clays that erode slowly under50-mm (2-in.), 180-mm (7-in.), or 380-mm (15-in.) head.ND2, ND1Nondispersive clay with very slight to nocolloidal erosion under 380-mm (15-in.) head.8. Apparatus8.1 Pinhole Test ApparatusTypic
45、al pinhole test apparatusis shown in Fig. 1, Fig. 2, and Fig. 3. Various other types andsizes of specimen molds or containers and top and base platesmay be used provided the test specimen is 38 mm (1.5 in.)long, the pinhole is 1.0 mm (0.04 in.) in diameter, and the holethrough the truncated cone cen
46、tering guide or other centeringdevice is 1.5 mm (0.059 in.) in diameter.8.1.1 It is important that the outlet drain be large enough toaccommodate the maximum inflow without creating a partialvacuum in the system. Partial vacuum may develop when smalldiameter outlet drains flow at full capacity and w
47、hen longsegments of flexible tubing are attached to the outflow pipe.8.1.2 The development of partial vacuum in the systemproduces hydraulic heads greater than those specified for thetest in Section 10 and following.8.1.3 The installation of a 1.6-mm (116-in.) to 3-mm (18-in.)diameter breather hole
48、in the center of the base plate, as shownin Fig. 1, generally assures discharge from the system atatmospheric pressure without partial vacuum.8.2 Constant Head Tank, to supply distilled water with a pHof 5.5 to 7.0.8.3 Graduated Cylinders, of 10, 25, 50, and 100-mL capac-ity.8.4 Wire Screen, with ho
49、les smaller than 2 mm (0.08 in.),cut in circular shape to fit inside the specimen tube.FIG. 1 Schematic Drawing of the Pinhole Test EquipmentD 4647 06138.5 Wire Punch, 1.0 mm (0.039 in.) in diameter by 50 to75-mm (2.5 to 3-in.) punch. (No. 19 veterinarian hypodermicneedle or 1-mm drill bit or stiff wire length.)8.6 Centering GuideTruncated cone centering guide with1.5-mm (0.059-in.) diameter hole (plastic, brass, steel, or othersuitable material).8.7 Coarse Sand, that has been washed and sieved throughNo. 10 to14-in. sieves (2 to 6 mm in diameter).8.8 Stop
