1、Designation: D4647 061D4647/D4647M 13Standard Test MethodMethods forIdentification and Classification of Dispersive Clay Soils bythe Pinhole Test1This standard is issued under the fixed designation D4647;D4647/D4647M; the number immediately following the designation indicatesthe year of original ado
2、ption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1 NOTESection 10.1.14 was editorially corrected in September 2009.1. Scope*1.1 This
3、 test method presents a direct, qualitative measurement of the dispersibility and consequent colloidal erodibility of claysoils by causing water to flow through a small hole punched in a specimen. The results of the tests are qualitative and providegeneral guidance regarding dispersibility and erodi
4、bility. This test method is complemented by Test Method D4221.1.2 This test method and the criteria for evaluating test data are based upon results of several hundred tests on samples collectedfrom embankments, channels, and other areas where clay soils have eroded or resisted erosion in nature (1).
5、21.3 Three alternative procedures for classifying the dispersibility of clay soils are provided as follows:1.3.1 Method A and Method C, adapted from Ref (1), classify soils into six categories of dispersiveness as: dispersibility (D1,D2), slight to moderately dispersive (ND4, ND3), and nondispersive
6、 (ND2, ND1).1.3.2 Method B classifies soils into three categories of dispersiveness as: dispersibility (D), slightly dispersive (SD), andnondispersive (ND).1.4 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in PracticeD6026.1.5 Unit
7、sThe values stated in either SI units or inch-pound units are to be regarded separately as the standard. The valuesgiven in parentheses are provided for information only.stated in each system may not be exact equivalents; therefore, each systemshall be used independently of the other. Combining valu
8、es from the two systems may result in non-conformance with the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine t
9、he applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D422 Test Method for Particle-Size Analysis of SoilsD653 Terminology Relating to Soil, Rock, and Contained FluidsD698 Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort
10、 (12 400 ft-lbf/ft3 (600 kN-m/m3)D1193 Specification for Reagent WaterD2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by MassD2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)D2488 Practice for Descrip
11、tion and Identification of Soils (Visual-Manual Procedure)D3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD4221 Test Method for Dispersive Characteristics of Clay Soil by Double HydrometerD4318 Te
12、st Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils1 This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.06 on Physical-ChemicalInteractions of Soil and Rock.Current edition approved Nov. 1, 2006
13、Jan. 1, 2013. Published December 2006 February 2013. Originally approved in 1987. Last previous edition approved in 19982006as D4647 93D4647(2006). 061. DOI: 10.1520/D4647-06E01.10.1520/D4647_D4647M-13.2 The boldface numbers in parentheses refer to the list of references at the end of thisthese test
14、 method.methods.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is
15、intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the c
16、urrent versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D4753 Guide for Evaluating,
17、Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and ConstructionMaterials TestingD6026 Practice for Using Significant Digits in Geotechnical Data3. Terminology3.1 Definitions:3.1.1 For definitions of terms in thisthese test method,methods, refer to Terminology D653.3.2
18、Definitions of Terms Specific to This Standard:3.2.1 dispersive claysclays that diaggregatedisaggregate easily and rapidly in water of low-salt concentration, and withoutsignificant mechanical assistance. Such clays usually have a high proportion of their adsorptive capacity saturated with sodiumcat
19、ions.3.2.1.1 DiscussionSuch clays generally have a high shrink-swell potential, have low resistance to erosion, and have low permeability in an intact state.4. Summary of Test Method4.1 The test method is started with distilled water flowing horizontally under a hydraulic head of 50 mm (2 in.)2 in.
20、througha 1.0-mm (0.04-in.)0.04-in. diameter hole punched in the soil specimen. The nature of the solution emerging from the specimenunder the intialinitial 50-mm (2-in.)2-in. head provides the principle differentiation between dispersive and nondispersive clays.Flow from dispersive clays will be dis
21、tinctly dark and the hole through the specimen will enlarge rapidly, with a resultant increasein the flow rate. Flow from slightly to moderately dispersive clays will be slightly dark with a constant hole size and flow rate.Flow from nondispersive clays will be completely clear with no measurable in
22、crease in the hole size.4.2 Test results are evaluated from the appearance of the flowing solution emerging from the specimen, the rate of flow, andthe final size of the hole through the specimen. These observations provide the basis for classifying the soil specimen.5. Significance and Use5.1 The p
23、inhole test provides one method of identifying the dispersive characteristics of clay soils that are to be or have beenused in earth construction. The piping failures of a number of homogeneous earth dams, erosion along channel or canal banks, andrainfall erosion of earthen structures have been attr
24、ibuted to the colloidal erosion along cracks or other flow channels formed inmasses of dispersive clay (2).5.2 This test method models the action of water flowing along a crack in an earth embankment. Other indirect tests, such as thedouble hydrometer test (Test Method D4221), the crumb test (3, 4),
25、 that relates the turbidity of a cloud of suspended clay colloidsas an indicator of the clay dispersivity, and chemical tests that relate the percentage of sodium to total soluble salt content of thesoil are also used as indicator tests of clay dispersibility (2). The comparison of results from the
26、pinhole test and other indirect testson hundreds of samples indicates that the results of the pinhole test have the best correlation with the erosional performance ofclay soils in nature.5.3 Method A and Method C of the pinhole test require the evaluation of cloudiness of effluent, final size of the
27、 pinhole, andcomputation of flow rates through the pinhole in order to classify the dispersive characteristics of the soil. Method B requires onlythe evaluation of the cloudiness of effluent and final size of the pinhole to classify the dispersive characteristics of the soil. Thecomputation of flow
28、rates through the pinhole in Method A serves primarily as a guide to the proper equipment and specimenperformance under sequential pressures applied during the test. All methods produce similar results and any method can be usedto identify dispersive clays.5.4 The use of Method A or Method C results
29、 in the accumulation of data relative to sequential flow rates through the pinholeand consequent enlargement or erosion of the hole. The pinhole erosion test was developed for the purpose of identifyingdispersive soils and is not intended to be a geometrically scaled model of a prototype structure.
30、Since the theory of similitude wasnot used in the design of the pinhole test, quantitative data are not obtained. The quantity of flow through the pinhole, amount ofsoil erosion, or the rate of soil erosion should not be extrapolated to actual field conditions (3). However, such data may be usefulin
31、 performing qualitative evaluations of the consequences of such erosion in terms of dam failure, loss of life and property. Theyalso may be used in considering the cost effectiveness of defensive design measures necessary to minimize the effects of failuredue to dispersive clays. For example, the am
32、ount of colloidal erosion that will occur in a soil classed as ND2 (very slightlydispersive) will be very small for a relatively long period of time. Such erosion may not be significant in evaluating the cost-benefitrelationships in projects where public safety is not involved or where normal mainte
33、nance procedures will handle the problem. Insuch cases, classifying the soil as ND (nondispersive) using Method B of the pinhole test should be adequate.5.5 Pinhole tests that result in classifying soil as slightly dispersive (ND3 by Method A or Method C or SD by Method B)indicate high uncertainty a
34、bout the existence of significant problems to be considered in the design or stability of a structure. InD4647/D4647M 132such cases, it is advisable to resample and test a number of other soils from the same area to generate an adequate statistical samplefor problem evaluation. The original slightly
35、 dispersive sample may come from an area on the edge of a more highly dispersivesoil.5.6 In a few physiographic areas or geoclimatic conditions, or both, neither the pinhole test nor the other indicator tests provideconsistent identification of dispersive clays (5, 6, 7). In such cases, the results
36、of the tests (8, 9) should be evaluated in terms ofcost effectiveness and design judgment (7).5.7 For some projects, it may be desirable to perform the pinhole test using eroding fluids other than distilled water (8, 10). Insuch cases, Method A, Method B, or Method C may be used to identify the disp
37、ersive characteristics of the soil and compare theresults with those obtained using distilled water.NOTE 1Notwithstanding the statement on precision and bias contained in thisthese test method:methods: The precision of thisthese testmethodmethods is dependent on the competence of the personnel perfo
38、rming it, and the suitability of the equipment and facilities used. Agencies whichmeet the criteria of Practice D3740 are generally considered capable of competent and objective testing. Users of thisthese test methodmethods arecautioned that compliance with Practice D3740 does not in itself assure
39、reliable testing. Reliable testing depends on several factors; Practice D3740provides a means of evaluating some of those factors.6. Limitations6.1 Development of the test procedure to provide reproducible results that differentiate between clay soils that were known tobe erodible (dispersive) and n
40、onerodible (nondispersive) in the field indicates the following limitations in the use of this test:6.1.1 This test method is not applicable to soils with less than 12 % fraction finer than 0.005 mm and with a plasticity indexless than or equal to 4 (2, 11). Such soils generally have low resistance
41、to erosion regardless of dispersive characteristics.6.1.2 The most consistent results are produced when the natural water content of the sample is preserved during the sampling,shipping, storage, and testing operations.6.1.3 Afew instances have been reported in which the pinhole test did not identif
42、y some dispersive clays in which the pore watercontained less than 0.4 meq/L total soluble salts that were more than 80 % sodium salts.6.1.4 This test method was developed to test specimens of disturbed soil that are compacted into the test cylinder. This testmethod can also be used to test undistur
43、bedintact specimens when they are properly trimmed and sealed into the test cylinder;however, some investigators (6) have found that thisthese test method ismethods are not applicable in evaluating the dispersivecharacteristics of undisturbedintact specimens of highly sensitive clays. Such clays may
44、 be classed as dispersive from the pinholetest results but perform as nondispersive materials in nature.6.1.5 This test method is performed with distilled water, at a pH of 5.5 to 7.0, as the eroding fluid. The use of water with variousionic concentrations and combinations will alter the results of
45、the test (8, 10).7. Classification7.1 The observations of thisthese test methodmethods provide the basis for classifying the soil specimen into a category ofdispersiveness according to the following general criteria:7.1.1 Method A:D1, D2Dispersive clays that fail rapidly under 50-mm (2-in.)2-in. hea
46、d.ND4, ND3Slightly to moderately dispersive clays that erode slowly under 50-mm (2-in.)2-in. or 180-mm (7-in.)7-in. head.ND2, ND1Nondispersive clay with very slight to no colloidal erosion under 380-mm (15-in.)15-in. or 1020-mm(40-in.)40-in. head.7.1.2 Method B:DDispersive clays that erode rapidly u
47、nder 50-mm (2-in.)2-in. head.SDSlightly dispersive clays that erode slowly under 180-mm (7-in.)7-in. head.NDNondispersive clays that show very slight or no colloidal erosion under 380-mm (15-in.)15-in. head.NOTE 2Method B for classifying dispersiveness of clay soils combines the categories of Method
48、 A as follows: D = D1, D2, ND4; SD = ND3; andND = ND2, ND1.7.1.3 Method C:D1, D2Dispersive clays that fail rapidly under 50-mm (2-in.)2-in. head.ND4, ND3Dispersive clays that erode slowly under 50-mm (2-in.),2-in., 180-mm (7-in.),7-in., or 380-mm (15-in.)15-in.head.ND2, ND1Nondispersive clay with ve
49、ry slight to no colloidal erosion under 380-mm (15-in.)15-in. head.8. Apparatus8.1 Pinhole Test ApparatusTypical pinhole test apparatus is shown in Fig. 1, Fig. 2, and Fig. 3. Various other types and sizesof specimen molds or containers and top and base plates may be used provided the test specimen is 38 mm (1.5 in.)1.5 in. long,the pinhole is 1.0 mm (0.04 in.)0.04 in. in diameter, and the hole through the truncated cone centering guide or other centeringdevice is 1.5 mm (0.059 in.)0.059 in. in diameter.D4647/D4647M 133
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