1、Designation: D 2487 06Standard Practice forClassification of Soils for Engineering Purposes (UnifiedSoil Classification System)1This standard is issued under the fixed designation D 2487; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This practice desc
3、ribes a system for classifying mineraland organo-mineral soils for engineering purposes based onlaboratory determination of particle-size characteristics, liquidlimit, and plasticity index and shall be used when preciseclassification is required.NOTE 1Use of this standard will result in a single cla
4、ssification groupsymbol and group name except when a soil contains 5 to 12 % fines orwhen the plot of the liquid limit and plasticity index values falls into thecrosshatched area of the plasticity chart. In these two cases, a dual symbolis used, for example, GP-GM, CL-ML. When the laboratory test re
5、sultsindicate that the soil is close to another soil classification group, theborderline condition can be indicated with two symbols separated by aslash. The first symbol should be the one based on this standard, forexample, CL/CH, GM/SM, SC/CL. Borderline symbols are particularlyuseful when the liq
6、uid limit value of clayey soils is close to 50. These soilscan have expansive characteristics and the use of a borderline symbol(CL/CH, CH/CL) will alert the user of the assigned classifications ofexpansive potential.1.2 The group symbol portion of this system is based onlaboratory tests performed o
7、n the portion of a soil samplepassing the 3-in. (75-mm) sieve (see Specification E11).1.3 As a classification system, this standard is limited tonaturally occurring soils.NOTE 2The group names and symbols used in this test method maybe used as a descriptive system applied to such materials as shale,
8、claystone, shells, crushed rock, etc. See Appendix X2.1.4 This standard is for qualitative application only.NOTE 3When quantitative information is required for detailed de-signs of important structures, this test method must be supplemented bylaboratory tests or other quantitative data to determine
9、performancecharacteristics under expected field conditions.1.5 This standard is the ASTM version of the Unified SoilClassification System. The basis for the classification schemeis the Airfield Classification System developed by A. Casa-grande in the early 1940s.2It became known as the UnifiedSoil C
10、lassification System when several U.S. GovernmentAgencies adopted a modified version of the Airfield System in1952.1.6 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
11、safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.7 This practice offers a set of instructions for performingone or more specific operations. This document cannot replaceeducation or experience and should be used in conjunctionwith professional jud
12、gment. Not all aspects of this practice maybe applicable in all circumstances. This ASTM standard is notintended to represent or replace the standard of care by whichthe adequacy of a given professional service must be judged,nor should this document be applied without consideration ofa projects man
13、y unique aspects. The word “Standard” in thetitle of this document means only that the document has beenapproved through the ASTM consensus process.2. Referenced Documents2.1 ASTM Standards:3C117 Test Method for Materials Finer than 75-m (No.200) Sieve in Mineral Aggregates by WashingC 136 Test Meth
14、od for Sieve Analysis of Fine and CoarseAggregatesC 702 Practice for Reducing Samples of Aggregate toTesting SizeD 420 Guide to Site Characterization for Engineering De-sign and Construction PurposesD 422 Test Method for Particle-Size Analysis of SoilsD 653 Terminology Relating to Soil, Rock, and Co
15、ntainedFluids1This standard is under the jurisdiction of ASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.07 on Identification andClassification of Soils.Current edition approved May 1, 2006. Published June 2006. Originallyapproved in 1966. Last previous editio
16、n approved in 2000 as D 2487 00.2Casagrande, A., “Classification and Identification of Soils,” Transactions,ASCE, 1948, p. 901.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information
17、, 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.D 1140 Test Method for Amount of Material in Soils Fi
18、nerThan the No. 200 (75-m) SieveD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 2217 Practice for Wet Preparation of Soil Samples forParticle-Size Analysis and Determination of Soil Con-stantsD 2488 Practice for Description and Identification o
19、f Soils(Visual-Manual Procedure)D 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD 4083 Practice for Description of Frozen Soils (Visual-Manual Procedure)D 4318 Test Methods for Liquid Limit, P
20、lastic Limit, andPlasticity Index of SoilsD 4427 Classification of Peat Samples by Laboratory Test-ingD 6913 Test Methods for Particle-Size Distribution (Grada-tion) of Soils Using Sieve AnalysisE11 Specification for Wire Cloth and Sieves for TestingPurposes3. Terminology3.1 DefinitionsExcept as lis
21、ted below, all definitions arein accordance with Terminology D 653.NOTE 4For particles retained on a 3-in. (75-mm) U.S. standard sieve,the following definitions are suggested:Cobblesparticles of rock that will pass a 12-in. (300-mm) squareopening and be retained on a 3-in. (75-mm) U.S. standard siev
22、e, andBouldersparticles of rock that will not pass a 12-in. (300-mm) squareopening.3.1.1 claysoil passing a No. 200 (75-m) U.S. standardsieve that can be made to exhibit plasticity (putty-like proper-ties) within a range of water contents and that exhibitsconsiderable strength when air dry. For clas
23、sification, a clay isa fine-grained soil, or the fine-grained portion of a soil, with aplasticity index equal to or greater than 4, and the plot ofplasticity index versus liquid limit falls on or above the “A”line.3.1.2 gravelparticles of rock that will pass a 3-in. (75-mm) sieve and be retained on
24、a No. 4 (4.75-mm) U.S. standardsieve with the following subdivisions:Coarsepasses 3-in. (75-mm) sieve and retained on34-in.(19-mm) sieve, andFinepasses34-in. (19-mm) sieve and retained on No. 4(4.75-mm) sieve.3.1.3 organic claya clay with sufficient organic content toinfluence the soil properties. F
25、or classification, an organic clayis a soil that would be classified as a clay except that its liquidlimit value after oven drying is less than 75 % of its liquid limitvalue before oven drying.3.1.4 organic silta silt with sufficient organic content toinfluence the soil properties. For classificatio
26、n, an organic siltis a soil that would be classified as a silt except that its liquidlimit value after oven drying is less than 75 % of its liquid limitvalue before oven drying.3.1.5 peata soil composed of vegetable tissue in variousstages of decomposition usually with an organic odor, adark-brown t
27、o black color, a spongy consistency, and a textureranging from fibrous to amorphous.3.1.6 sandparticles of rock that will pass a No. 4 (4.75-mm) sieve and be retained on a No. 200 (75-m) U.S. standardsieve with the following subdivisions:Coarsepasses No. 4 (4.75-mm) sieve and retained on No.10 (2.00
28、-mm) sieve,Mediumpasses No. 10 (2.00-mm) sieve and retained onNo. 40 (425-m) sieve, andFinepasses No. 40 (425-m) sieve and retained on No.200 (75-m) sieve.3.1.7 siltsoil passing a No. 200 (75-m) U.S. standardsieve that is nonplastic or very slightly plastic and that exhibitslittle or no strength whe
29、n air dry. For classification, a silt is afine-grained soil, or the fine-grained portion of a soil, with aplasticity index less than 4 or if the plot of plasticity indexversus liquid limit falls below the “A” line.3.2 Definitions of Terms Specific to This Standard:3.2.1 coeffcient of curvature, Ccth
30、e ratio (D30)2/(D103 D60), where D60,D30, and D10are the particle sizescorresponding to 60, 30, and 10 % finer on the cumulativeparticle-size distribution curve, respectively.3.2.2 coeffcient of uniformity, Cuthe ratio D60/D10, whereD60and D10are the particle diameters corresponding to 60 and10 % fi
31、ner on the cumulative particle-size distribution curve,respectively.4. Summary4.1 As illustrated in Table 1, this classification systemidentifies three major soil divisions: coarse-grained soils,fine-grained soils, and highly organic soils. These three divi-sions are further subdivided into a total
32、of 15 basic soil groups.TABLE 1 Soil Classification ChartCriteria for Assigning Group Symbols and Group Names Using Laboratory TestsASoil ClassificationGroup Symbol Group NameBCOARSE-GRAINEDSOILSGravels Clean Gravels Cu $ 4 and1 # Cc # 3CGW Well-graded gravelDMore than 50 %retained on No.200 sieveMo
33、re than 50 % ofcoarse fractionretained on No. 4sieveLess than 5 % finesECu Cc3CGP Poorly graded gravelDGravels with Fines Fines classify as MLor MHGM Silty gravelD,F,GD 2487 062TABLE 1 ContinuedCriteria for Assigning Group Symbols and Group Names Using Laboratory TestsASoil ClassificationGroup Symbo
34、l Group NameBMore than 12 % finesEFines classify as CL orCH,urule;1GC Clayey gravelD,F,GSands Clean Sands Cu $ 6 and1 # Cc # 3CSW Well-graded sandH50 % or more ofcoarseLess than 5 % finesICu Cc3CSP Poorly graded sandHfraction passes No. 4sieveSands with Fines Fines classify as MLor MHSM Silty sandF,
35、G,HMore than 12 % finesIFines classify as CL orCHSC Clayey sandF,G,HFINE-GRAINEDSOILSSilts and Clays inorganic PI 7 and plots on orabove “A” lineJCL Lean clayK,L,M50 % or more passesthe No.Liquid limit less than50PI 0.75OL Organic clayK,L,M,NLiquid limit not dried OL Organic siltK,L,M,OSilts and Cla
36、ys inorganic PI plots on or above“A” lineCH Fat clayK,L,MLiquid limit 50 or more PI plots below “A” line MH Elastic siltK,L,Morganic Liquid limit ovendried 0.75OH Organic clayK,L,M,PLiquid limit not dried Organic siltK,L,M,QHIGHLY ORGANICSOILSPrimarily organic matter, dark in color, and organic odor
37、 PT PeatABased on the material passing the 3-in. (75-mm) sieve.BIf field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name.CCu=D60/D10Cc 5 D30!2/D103 D60DIf soil contains $15 % sand, add “with sand” to group name.EGravels with 5 to 12 % fines requir
38、e dual symbols:GW-GM well-graded gravel with siltGW-GC well-graded gravel with clayGP-GM poorly graded gravel with siltGP-GC poorly graded gravel with clayFIf fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.GIf fines are organic, add “with organic fines” to group name.HIf soil contains $15
39、% gravel, add “with gravel” to group name.ISands with 5 to 12 % fines require dual symbols:SW-SM well-graded sand with siltSW-SC well-graded sand with claySP-SM poorly graded sand with siltSP-SC poorly graded sand with clayJIf Atterberg limits plot in hatched area, soil is a CL-ML, silty clay.KIf so
40、il contains 15 to 29 % plus No. 200, add “with sand” or “with gravel,” whichever is predominant.LIf soil contains $30 % plus No. 200, predominantly sand, add “sand ” to group name.MIf soil contains $30 % plus No. 200, predominantly gravel, add “gravelly” to group name.NPI $ 4 and plots on or above “
41、A” line.OPI 4 or plots below“ A” line.PPI plots on or above “A” line.QPI plots below “A” line.4.2 Based on the results of visual observations and pre-scribed laboratory tests, a soil is catalogued according to thebasic soil groups, assigned a group symbol(s) and name, andthereby classified. The flow
42、 charts, Fig. 1 for fine-grained soils,and Fig. 3 for coarse-grained soils, can be used to assign theappropriate group symbol(s) and name.5. Significance and Use5.1 This standard classifies soils from any geographic loca-tion into categories representing the results of prescribedlaboratory tests to
43、determine the particle-size characteristics,the liquid limit, and the plasticity index.5.2 The assigning of a group name and symbol(s) alongwith the descriptive information required in Practice D 2488can be used to describe a soil to aid in the evaluation of itssignificant properties for engineering
44、 use.5.3 The various groupings of this classification system havebeen devised to correlate in a general way with the engineeringbehavior of soils. This standard provides a useful first step inany field or laboratory investigation for geotechnical engineer-ing purposes.5.4 This standard may also be u
45、sed as an aid in trainingpersonnel in the use of Practice D 2488.5.5 This standard may be used in combination with PracticeD 4083 when working with frozen soils.NOTE 5Notwithstanding the statements on precision and bias con-tained in this standard: The precision of this test method is dependent onth
46、e competence of the personnel performing it and the suitability of theequipment and facilities used. Agencies that 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
47、not in itself assure reliable testing. Reliable testingD 2487 063FIG. 1 Flow Chart for Classifying Fine-Grained Soil (50 % or More Passes No. 200 Sieve)FIG. 2 Flow Chart for Classifying Organic Fine-Grained Soil (50 % or More Passes No. 200 Sieve)D 2487 064depends on several factors; Practice D 3740
48、 provides a means forevaluating some of those factors.6. Apparatus6.1 In addition to the apparatus that may be required forobtaining and preparing the samples and conducting theprescribed laboratory tests, a plasticity chart, similar to Fig. 4,and a cumulative particle-size distribution curve, simil
49、ar to Fig.5, are required.NOTE 6The “U” line shown on Fig. 4 has been empirically deter-mined to be the approximate “upper limit” for natural soils. It is a goodcheck against erroneous data, and any test results that plot above or to theleft of it should be verified.7. Sampling7.1 Samples shall be obtained and identified in accordancewith a method or methods, recommended in Guide D 420 or byother accepted procedures.7.2 Test Methods D 6913 provides guidance on selectingsize of specimen. Two test methods are provided in thisstandard. Th
