设计美标项目时，经常用到美标的岩土勘察报告，下面对其岩土的工程分类作一简单介绍，方便理解与应用。

Standard Practice for Classification ofSoils for Engineering Purposes

(Unified Soil Classification System)

工程岩土分类的标准实施规程

(岩土统一分类体系)

This standardis issued under the fixed designation D2487; the number immediately followingthe designation indicates the year of original adoption or, in the case ofrevision, the year of last revision. A number in parentheses indicates the yearof last reapproval. A superscript epsilon (ε)indicates an editorial change since the last revision or reapproval.

本标准以固定名称D2487发布；紧跟在名称后面的数字表示最初采用的年份，如果是修订版，则表示最后修订的年份。括号中的数字表示上次重新批准的年份。上标epsilon（ε）表示自上次修订或重新批准以来的编辑变更。

This standardhas been approved for use by agencies of the U.S. Department of Defense.

本规程已被美国国防部各机构批准使用。

1.Scope

1.1  This practice describes a system forclassifying mineral and organo-mineral soils for engineering purposes based onlaboratory determination of particle-size characteristics, liquid limit, andplasticity index and shall be used when precise classification is required.

1.适用范围

1.1本规程规定了一种基于实验室测定粒度特征、液限和塑性指数的工程用矿物和有机矿物岩土分类体系，并应在需要精确分类时使用。

NOTE 1—Use ofthis standard will result in a single classification group symbol and groupname except when a soil contains 5 to 12 % fines or when the plot of the liquidlimit and plasticity index values falls into the crosshatched area of theplasticity chart. In these two cases, a dual symbol is used, for example,GP-GM, CL-ML. When the laboratory test results indicate that the soil is closeto another soil classification group, the borderline condition can be indicatedwith two symbols separated by a slash. The first symbol should be the one basedon this standard, for example, CL/CH, GM/SM, SC/CL. Borderline symbols areparticularly useful when the liquid limit value of clayey soils is close to 50.These soils can have expansive characteristics and the use of a borderlinesymbol (CL/CH, CH/CL) will alert the user of the assigned classifications ofexpansive potential.

注1：使用本规程将产生一个单一的分类组符号和组名，除非岩土中含有5%至12%的细骨料，或液限和塑性指数值的图形位于塑性图表的交叉阴影区域。此时，使用双重符号，例如GP-GM、CL-ML。当实验室试验结果表明岩土接近另一个岩土分类组时，边界条件可用斜线分隔的两个符号表示。第一个符号应是基于本标准的符号，例如CL/CH、GM/SM、SC/CL。当粘性土的液限值接近50时，边界符号特别有用。这些岩土可能具有膨胀性，使用边界符号(CL/CH，CH/CL)将提醒用户指定的膨胀可能分类。

1.2  The group symbol portion of this system isbased on laboratory tests performed on the portion of a soil sample passing the3-in. (75-mm) sieve (see Specification E11).

1.2本体系的组码部分根据对通过75mm筛的岩土样本部分进行的实验室试验确定(见规范E11)。 

1.3  As a classification system, this standard islimited to naturally occurring soils.

NOTE2—The group names and symbols used in this test method may be used as adescriptive system applied to such materials as shale, claystone, shells,crushed rock, etc. See Appendix X2.

1.3作为一个分类体系，本规程仅限于天然岩土。

注2：本试验方法中使用的组名和符号可用作描述体系，用于页岩、粘土岩、贝壳岩、碎岩等材料。见附录X2。

1.4  This standard is for qualitative applicationonly.

NOTE3—When quantitative information is required for detailed designs of importantstructures, this test method must be supplemented by laboratory tests or otherquantitative data to determine performance characteristics under expected fieldconditions.

1.4本规程仅用于定性使用。

注3：当重要结构的详细设计需要定量信息时，必须通过实验室试验或其他定量数据来补充该试验方法，以确定预期现场条件下的性能特征。

1.5  This standard is the ASTM version of theUnified Soil Classification System. The basis for the classification scheme isthe Airfield Classification System developed by A. Casagrande in the early1940s.² It became known as the Unified Soil Classification Systemwhen several U.S. Government Agencies adopted a modified version of theAirfield System in 1952.

1.5本规程是岩土统一分类体系的ASTM版本。分类方案的基础是A.Casagrande在20世纪40年代早期发展的机场分类体系。² 1952年，几个美国政府机构采用了机场体系的修改版本，该体系被称为岩土统一分类体系。

1.6  This standard does not purport to address allof the safety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatory limitationsprior to use.

1.6本规程无意解决与其使用相关的所有安全问题(如有)。本规程的使用者有责任在使用前建立适当的安全和健康实践，并确定监管限制的适用性。

1.7  This practice offers a set of instructions forperforming one or more specific operations. This document cannot replaceeducation or experience and should be used in conjunction with professionaljudgment. Not all aspects of this practice may be applicable in allcircumstances. This ASTM standard is not intended to represent or replace thestandard of care by which the adequacy of a given professional service must bejudged, nor should this document be applied without consideration of aproject’s many unique aspects. The word “Standard” in the title of thisdocument means only that the document has been approved through the ASTMconsensus process.

1.7本规程提规定了一套用于执行一个或多个特定操作的说明。本规程不能取代教育或经验，应与专业判断结合使用。并非本惯例的所有方面都适用于所有情况。本ASTM规程不代表或取代必须根据其判断给定专业服务是否充分的谨慎标准，也不应在不考虑项目的许多独特方面的情况下应用本规程。本规程标题中的“规程”一词仅表示该规程已通过ASTM共识方法获得批准。