1、Designation: D2487 11Standard Practice forClassification of Soils for Engineering Purposes (UnifiedSoil Classification System)1This standard is issued under the fixed designation D2487; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This practice describ
3、es 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 classi
4、fication 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 resul
5、tsindicate 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 liquid
6、 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 on t
7、he 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,cla
8、ystone, 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 per
9、formancecharacteristics 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 Clas
10、sification 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 saf
11、ety 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 judgme
12、nt. 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 many u
13、nique 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 WashingC136 Test Method f
14、or Sieve Analysis of Fine and CoarseAggregatesC702 Practice for Reducing Samples of Aggregate to Test-ing SizeD420 Guide to Site Characterization for Engineering De-sign and Construction PurposesD422 Test Method for Particle-Size Analysis of SoilsD653 Terminology Relating to Soil, Rock, and Containe
15、dFluidsD1140 Test Methods for Amount of Material in Soils Finer1This practice 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, 2011. Published June 2011
16、. Originallyapproved in 1966. Last previous edition approved in 2010 as D248710. DOI:10.1520/D2487-11.2Casagrande, 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
17、at serviceastm.org. For Annual Book of ASTMStandards 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 19428-29
18、59, United States.than No. 200 (75-m) SieveD2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D3740 Practice for Minimum Requirements for AgenciesEngaged in Testing an
19、d/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4083 Practice for Description of Frozen Soils (Visual-Manual Procedure)D4318 Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of SoilsD4427 Classification of Peat Samples by Laboratory Test-ingD6913 Test
20、Methods for Particle-Size Distribution (Grada-tion) of Soils Using Sieve AnalysisE11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Terminology3.1 DefinitionsExcept as listed below, all definitions arein accordance with Terminology D653.NOTE 4For particles retained on a 3-in. (75-mm)
21、 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 sieve, andBouldersparticles of rock that will not pass a 12-in. (300-mm) squareopening.3.1.1 claysoil passing a No. 20
22、0 (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 classification, a clay isa fine-grained soil, or the fine-grained portion of a soil, with aplasticity index equal to o
23、r 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 a No. 4 (4.75-mm) U.S. standardsieve with the following subdivisions:Coarsepasses 3-in. (75-mm) sieve and retained
24、 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. For classification, an organic clayis a soil that would be classified as a clay except that its liquidlimit value a
25、fter 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 classification, an organic siltis a soil that would be classified as a silt except that its liquidlimit value after oven drying
26、 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 to black color, a spongy consistency, and a textureranging from fibrous to amorphous.3.1.6 sandparticles of rock th
27、at 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-mm) sieve,Mediumpasses No. 10 (2.00-mm) sieve and retained onNo. 40 (425-m) sieve, andFinepasses No. 40 (425-m) s
28、ieve 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 when air dry. For classification, a silt is afine-grained soil, or the fine-grained portion of a soil, with aplastici
29、ty 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, Ccthe ratio (D30)2/(D103 D60), where D60,D30, and D10are the particle sizescorresponding to 60, 30, and 10 % finer on
30、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 % finer on the cumulative particle-size distribution curve,respectively.4. Summary4.1 As illustrated in Table 1, this
31、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 of 15 basic soil groups.4.2 Based on the results of visual observations and pre-scribed laboratory tests, a soil i
32、s catalogued according to thebasic soil groups, assigned a group symbol(s) and name, andthereby classified. The flow 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 class
33、ifies soils from any geographic loca-tion into categories representing the results of prescribedlaboratory tests to 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
34、 Practice D2488can be used to describe a soil to aid in the evaluation of itssignificant properties for engineering 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
35、step inany field or laboratory investigation for geotechnical engineer-ing purposes.5.4 This standard may also be used as an aid in trainingpersonnel in the use of Practice D2488.5.5 This standard may be used in combination with PracticeD4083 when working with frozen soils.NOTE 5Notwithstanding the
36、statements on precision and bias con-tained in this standard: The precision of this test method is dependent onthe competence of the personnel performing it and the suitability of theequipment and facilities used. Agencies that meet the criteria of PracticeD2487 112D3740 are generally considered cap
37、able of competent and objectivetesting. Users of this test method are cautioned that compliance withPractice D3740 does not in itself assure reliable testing. Reliable testingdepends on several factors; Practice D3740 provides a means forevaluating some of those factors.6. Apparatus6.1 In addition t
38、o 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, similar to Fig.5, are required.NOTE 6The “U” line shown on Fig. 4 has been empirically d
39、eter-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
40、D420 or byother accepted procedures.7.2 Test Methods D6913 provides guidance on selectingsize of specimen. Two test methods are provided in thisstandard. The methods differ in the significant digits recordedTABLE 1 Soil Classification ChartSoil ClassificationCriteria for Assigning Group Symbols and
41、Group Names Using Laboratory TestsAGroupSymbolGroup NameBCOARSE-GRAINED SOILS Gravels(More than 50 %of coarse fraction retained onNo. 4 sieve)Clean Gravels(Less than 5 % finesC)Cu $ 4 and 1 # Cc # 3DGW Well-graded gravelEMore than 50 %retained on No. 200 sieveCu 3DGP Poorly graded gravelEGravels wit
42、h Fines(More than 12 % finesC)Fines classify as ML or MH GM Silty gravelE,F,GFines classify as CL or CH GC Clayey gravelE,F,GSands(50 % or more of coarsefraction passesNo. 4 sieve)Clean Sands(Less than 5 % finesH)Cu $ 6 and 1 # Cc # 3DSW Well-graded sandICu 3DSP Poorly graded sandISands with Fines(M
43、ore than 12 % finesH)Fines classify as ML or MH SM Silty sandF,G,IFines classify as CL or CH SC Clayey sandF,G,IFINE-GRAINED SOILS Silts and Clays inorganic PI 7 and plots on or above “A” lineJCL Lean clayK,L,M50 % or morepasses the No. 200 sieveLiquid limitless than 50PI 4 or plots below “A” lineJM
44、L SiltK,L,MorganicLiquid limit 2 oven driedLiquid limit 2 not dried 0.75OL Organic clayK,L,M,NOrganic siltK,L,M,OSilts and Clays inorganic PI plots on or above “A” line CH Fat clayK,L,MLiquid limit50 or morePI plots below “A” line MH Elastic siltK,L,MorganicLiquid limit 2 oven driedLiquid limit 2 no
45、t dried 0.75OH Organic clayK,L,M,POrganic siltK,L,M,QHIGHLY ORGANIC SOILS Primarily organic matter, dark in color, and organic odor 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
46、name.CGravels with 5 to 12 % fines require 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 clayDCu=D60/D10Cc 5 D30!2/D103 D60EIf soil contains $15 % sand, add “with sand” to group name.FIf fines clas
47、sify as CL-ML, use dual symbol GC-GM, or SC-SM.GIf fines are organic, add “with organic fines” to group name.HSands 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 clayIIf soil c
48、ontains $15 % gravel, add “with gravel” to group name.JIf Atterberg limits plot in hatched area, soil is a CL-ML, silty clay.KIf soil contains 15 to 30 % plus No. 200, add “with sand” or “with gravel,” whichever is predominant.LIf soil contains $30 % plus No. 200, predominantly sand, add “sand ” to
49、group name.MIf soil contains $30 % plus No. 200, predominantly gravel, add “gravelly” to group name.NPI $ 4 and plots on or above “A” line.OPI 4 or plots below “A” line.PPI plots on or above “A” line.QPI plots below “A” line.D2487 113and the size of the specimen (mass) required. The method to beused may be specified by the requesting authority; otherwiseMethod A shall be performed. Whenever possible, the fieldsamples should have weights two to four times larger thanshown.7.3 If the field sample or test specimen is smaller than theminimum recom
