1、Designation: D2166/D2166M 16Standard Test Method forUnconfined Compressive Strength of Cohesive Soil1This standard is issued under the fixed designation D2166/D2166M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last
2、 revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the uncon-fined compressive strength of cohesive soil in the intact,remolded
3、, or reconstituted condition, using strain-controlledapplication of the axial load.1.2 This test method provides an approximate value of thestrength of cohesive soils in terms of total stresses.1.3 This test method is applicable only to cohesive materialswhich will not expel or bleed water (water ex
4、pelled from thesoil due to deformation or compaction) during the loadingportion of the test and which will retain intrinsic strength afterremoval of confining pressures, such as clays or cementedsoils. Dry and crumbly soils, fissured or varved materials, silts,peats, and sands cannot be tested with
5、this method to obtainvalid unconfined compression strength values.NOTE 1The determination of the unconsolidated, undrained strengthof cohesive soils with lateral confinement is covered by Test MethodD2850.1.4 This test method is not a substitute for Test MethodD2850.1.5 All observed and calculated v
6、alues shall conform to theguidelines for significant digits and rounding established inPractice D6026, unless superseded by this standard.1.5.1 The procedures used to specify how data are collected/recorded and calculated in this test method are regarded as theindustry standard. In addition, they ar
7、e representative of thesignificant digits that should generally be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives; and it is common practice toincrease or reduce significant di
8、gits of reported data to com-mensurate with these considerations. It is beyond the scope ofthis test method to consider significant digits used in analysismethods for engineering design.1.6 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values
9、stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.6.1 The gravitational system of inch-pound units is usedwhen dealing with inch-pound units. In this
10、 system, the pound(lbf) represents a unit of force (weight), while the unit for massis slugs. The rationalized slug unit is not given, unless dynamic(F = ma) calculations are involved.1.6.2 It is common practice in the engineering/constructionprofession to concurrently use pounds to represent both a
11、 unitof mass (lbm) and of force (lbf). This implicitly combines twoseparate systems of units; that is, the absolute system and thegravitational system. It is scientifically undesirable to combinethe use of two separate sets of inch-pound units within a singlestandard. As stated, this standard includ
12、es the gravitationalsystem of inch-pound units and does not use/present the slugunit for mass. However, the use of balances or scales recordingpounds of mass (lbm) or recording density in lbm/ft3shall notbe regarded as nonconformance with this standard.1.7 This standard does not purport to address a
13、ll of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standard 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:2D653 Terminology Re
14、lating to Soil, Rock, and ContainedFluidsD854 Test Methods for Specific Gravity of Soil Solids byWater PycnometerD1587 Practice for Thin-Walled Tube Sampling of Fine-Grained Soils for Geotechnical PurposesD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by
15、MassD2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current edition approved July 1, 201
16、6. Published July 2016. Originally approvedin 1963. Last previous edition approved in 2013 as D2166 13. DOI: 10.1520/D2166_D2166M-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume infor
17、mation, refer to the standards Document Summary page onthe ASTM website.*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 States1D2850 Test Method for Unconsolidated-Undrained Tr
18、iaxialCompression Test on Cohesive SoilsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4220 Practices for Preserving and Transporting SoilSamplesD4318 Test Methods for Liquid Limit, Plastic Limit
19、, andPlasticity Index of SoilsD6026 Practice for Using Significant Digits in GeotechnicalDataD6913 Test Methods for Particle-Size Distribution (Grada-tion) of Soils Using Sieve AnalysisD7263 Test Methods for Laboratory Determination of Den-sity (Unit Weight) of Soil SpecimensE177 Practice for Use of
20、 the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions:3.1.1 For definitions of common technical terms in thisstandard, refer to Terminology D653.3.2 Definitions of Terms Specific
21、to This Standard:3.2.1 unconfined compressive strength (qu)the compres-sive stress at which an unconfined cylindrical specimen of soilwill fail in a simple compression test; in this test method,unconfined compressive strength is taken as the maximum loadattained per unit area or the load per unit ar
22、ea at 15 % axialstrain, whichever is secured first during the performance of atest.3.2.2 shear strength (su)for unconfined compressivestrength test specimens, the shear strength is calculated to be12 of the compressive stress at failure, as defined in 3.2.1.4. Summary of Test Method4.1 In this test
23、method, a cylindrical soil specimen isunconfined laterally while loaded axially at an axial strain ratebetween 0.5 to 2 %/min. Measurements are made of elapsedtime, axial deformation, and axial load. The unconfined com-pressive stress, qu, is calculated as the compressive stress atfailure. The shear
24、 strength, su, is one half of the unconfinedcompressive strength.5. Significance and Use5.1 The primary purpose of the unconfined compression testis to quickly obtain a measure of compressive strength forthose soils that possess sufficient cohesion to permit testing inthe unconfined state.5.2 Sample
25、s of soils having slickensided or fissuredstructure, samples of some types of loess, very soft clays, dryand crumbly soils and varved materials, or samples containingsignificant portions of silt or sand, or both (all of which usuallyexhibit cohesive properties), frequently display higher shearstreng
26、ths when tested in accordance with Test Method D2850.Also, unsaturated soils will usually exhibit different shearstrengths when tested in accordance with Test Method D2850.5.3 If tests on the same sample in both its intact andremolded states are performed, the sensitivity of the materialcan be deter
27、mined. This method of determining sensitivity issuitable only for soils that can retain a stable specimen shapein the remolded state.NOTE 2For soils that will not retain a stable shape, a vane shear testor Test Method D2850 can be used to determine sensitivity.NOTE 3The quality of the result produce
28、d by this standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection. Users of this standard ar
29、ecautioned that compliance with Practice D3740 does not in itself ensurereliable results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors.6. Apparatus6.1 Compression DeviceThe compression device may bea platform weighing scale equipped with
30、 a screw-jack-activated load yoke, a hydraulic loading device, or any othercompression device with sufficient capacity and control toprovide the rate of loading prescribed in 8.1. The compressiondevice shall be capable of measuring the compressive stress tothree significant digits at the maximum str
31、ess, or within 1 kPa0.01 ton/ft2, whichever is larger.6.2 Sample Extruder, capable of extruding the soil core fromthe sampling tube at a uniform rate in the same direction oftravel in which the sample entered the tube, and with negligibledisturbance of the sample. Conditions at the time of samplerem
32、oval may dictate the direction of removal, but the principalconcern is to reduce the potential for additional disturbancebeyond that incurred during initial sampling.6.3 Deformation IndicatorThe deformation indicator shallbe a dial indicator graduated to 0.03 mm 0.001 in. or betterand having a trave
33、l range of at least 20 % of the length of thetest specimen, or some other measuring device, such as anelectronic deformation measuring device, meeting these re-quirements.6.4 Dial Comparator, or other suitable device, for measur-ing the physical dimensions of the specimen to within 0.1 % ofthe measu
34、red dimension.NOTE 4Vernier calipers are not recommended for soft specimens,which will deform as the calipers are applied on the specimen.6.5 TimerA timing device indicating the elapsed testingtime to the nearest second shall be used for establishing the rateof strain application prescribed in 8.1.6
35、.6 BalanceThe balance used to weigh specimens shalldetermine the mass of the specimen to within 0.1 % of its totalmass.6.7 Equipment, as specified in Test Method D2216.6.8 Miscellaneous Apparatus, including specimen trimmingand carving tools, remolding apparatus, water content cans,and data sheets,
36、as required.7. Preparation of Test Specimens7.1 Specimen SizeSpecimens shall have a minimum diam-eter of 30 mm 1.3 in. and the largest particle contained withinD2166/D2166M 162the test specimen shall be smaller than one tenth of thespecimen diameter. For specimens having a diameter of 72 mm2.8 in. o
37、r larger, the largest particle size shall be smaller thanone sixth of the specimen diameter. If, after completion of atest on an intact specimen, it is found, based on visualobservation, that larger particles than permitted are present,indicate this information in the remarks section of the report o
38、ftest data (Note 5). The height-to-diameter ratio shall bebetween 2 and 2.5. Determine the average height and diameterof the test specimen using the apparatus specified in 6.4. Takea minimum of three height measurements (approximately 120apart), and at least three diameter measurements at approxi-ma
39、tely the quarter points of the height.NOTE 5If large soil particles are found in the specimen after testing,a particle-size analysis performed in accordance with Test Method D6913may be performed to confirm the visual observation and the resultsprovided with the test report.7.2 Intact SpecimensPrepa
40、re intact specimens from largesamples or from samples secured in accordance with PracticeD1587 and preserved and transported in accordance with thepractices for Group C samples in Practices D4220. Tubespecimens may be tested without trimming except for thesquaring of ends, if conditions of the sampl
41、e justify thisprocedure. Handle specimens carefully to reduce the potentialfor additional disturbance, changes in cross section, or loss ofwater content. If compression or any type of noticeabledisturbance would be caused by the extrusion device, split thesample tube lengthwise or cut it off in smal
42、l sections tofacilitate removal of the specimen with minimal disturbance.Prepare carved specimens with minimal disturbance, andwhenever possible, in a humidity-controlled room. Make everyeffort to prevent a change in water content of the soil.Specimens shall be of uniform circular cross section with
43、 endsperpendicular to the longitudinal axis of the specimen. Whencarving or trimming, remove any small pebbles or shellsencountered. Carefully fill voids on the surface of the specimenwith remolded soil obtained from the trimmings. When pebblesor crumbling result in excessive irregularity at the end
44、s, cap thespecimen with a minimum thickness of plaster of paris,hydrostone, or similar material. When sample conditionpermits, a vertical lathe that will accommodate the total samplemay be used as an aid in carving the specimen to the requireddiameter. Determine the mass and dimensions of the testsp
45、ecimen. If the specimen is to be capped, its mass anddimensions should be determined before capping. If the entiretest specimen is not to be used for determination of watercontent, secure a representative sample of trimmings for thispurpose, placing them immediately in a covered container. Thewater
46、content determination shall be performed in accordancewith Test Method D2216. Initial dry density determinationshall be performed in accordance with Test Method D7263.7.3 Remolded SpecimensSpecimens may be prepared ei-ther from a failed intact specimen or from a disturbed sample,providing it is repr
47、esentative of the failed intact specimen. Inthe case of failed intact specimens, wrap the material in a thinrubber membrane and work the material thoroughly with thefingers to assure complete remolding. Avoid entrapping air inthe specimen. Exercise care to obtain a uniform density, toremold to the s
48、ame void ratio as the intact specimen, and topreserve the natural water content of the soil. Form thedisturbed material into a mold of circular cross section havingdimensions meeting the requirements of 7.1. After removalfrom the mold, determine the mass and dimensions of the testspecimens.7.4 Recon
49、stituted SpecimensSpecimens shall be preparedto the predetermined water content and density prescribed bythe individual assigning the test (Note 6). After a specimen isformed, trim the ends perpendicular to the longitudinal axis,remove from the mold, and determine the mass and dimensionsof the test specimen.NOTE 6Experience indicates that it is difficult to compact, handle, andobtain valid results with specimens that have a degree of saturation that isgreater than 90 %.8. Procedure8.1 Place the specimen in the loading device so that it iscentered on the bo
