1、Designation: D 2166 06Standard Test Method forUnconfined Compressive Strength of Cohesive Soil1This standard is issued under the fixed designation D 2166; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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, or recons
3、tituted 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 expelled from
4、 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 this method
5、 to obtainvalid unconfined compression strength values.NOTE 1The determination of the unconsolidated, undrained strengthof cohesive soils with lateral confinement is covered by Test MethodD 2850.1.4 This test method is not a substitute for Test MethodD 2850.1.5 All observed and calculated values sha
6、ll conform to theguidelines for significant digits and rounding established inPractice D 6026.1.5.1 The procedures used to specify how data are collected/recorded and calculated in this test method are regarded as theindustry standard. In addition, they are representative of thesignificant digits th
7、at 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 digits of reported data to com-mensurate with
8、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 SI units are to be regarded as thestandard. The values stated in inch-pound units are approxi-mate.1.7 This standard does not purport
9、 to address all 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:2D 653
10、Terminology Relating to Soil, Rock, and ContainedFluidsD 854 Test Methods for Specific Gravity of Soil Solids byWater PycnometerD 1587 Practice for Thin-Walled Tube Sampling of Soilsfor Geotechnical PurposesD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Roc
11、k by MassD 2488 Practice for Description and Identification of Soils(Visual-Manual Procedure)D 2850 Test Method for Unconsolidated-Undrained Tri-axial Compression Test on Cohesive SoilsD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Us
12、ed in Engineering Design and ConstructionD 4220 Practices for Preserving and Transporting SoilSamplesD 4318 Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of SoilsD 6026 Practice for Using Significant Digits in Geotechni-cal DataD 6913 Test Methods for Particle-Size Distribution (
13、Grada-tion) of Soils Using Sieve AnalysisE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions: Refer to Terminology D 653 for standarddefinitions of ter
14、ms.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 15, 2006. Published January 2007. Originallyapproved in 1963. Last previous edition approv
15、ed in 2000 as D 2166 00e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service 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 appe
16、ars at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 Definitions of Terms Specific to This Standard:3.2.1 unconfined compressive strength (qu)the compres-sive stress at which an unconfined cylindrical sp
17、ecimen 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 area at 15 % axialstrain, whichever is secured first during the performance of atest.3.2.2 shear strength (su)for unconfin
18、ed compressivestrength test specimens, the shear strength is calculated to be12 of the compressive stress at failure, as defined in 3.2.1.4. Significance and Use4.1 The primary purpose of the unconfined compression testis to quickly obtain a measure of compressive strength forthose soils that posses
19、s sufficient cohesion to permit testing inthe unconfined state.4.2 Samples of soils having slickensided or fissured struc-ture, samples of some types of loess, very soft clays, dry andcrumbly soils and varved materials, or samples containingsignificant portions of silt or sand, or both (all of which
20、 usuallyexhibit cohesive properties), frequently display higher shearstrengths when tested in accordance with Test Method D 2850.Also, unsaturated soils will usually exhibit different shearstrengths when tested in accordance with Test Method D 2850.4.3 If tests on the same sample in both its intact
21、andremolded states are performed, the sensitivity of the materialcan be determined. 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 D 285
22、0 can be used to determine sensitivity.NOTE 3The quality of the result produced 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 D 3740 are generally considered capable o
23、f competentand objective testing/sampling/inspection. Users of this standard arecautioned that compliance with Practice D 3740 does not in itself ensurereliable results. Reliable results depend on many factors; Practice D 3740provides a means of evaluating some of those factors.5. Apparatus5.1 Compr
24、ession Device, The compression device may be aplatform weighing scale equipped with a screw-jack-activatedload yoke, a hydraulic loading device, or any other compres-sion device with sufficient capacity and control to provide therate of loading prescribed in 7.1. For soil with an unconfinedcompressi
25、ve strength of less than 100 kPa (1.0 ton/ft2) thecompression device shall be capable of measuring the com-pressive stress to within 1 kPa (0.01 ton/ft2). For soil with anunconfined compressive strength of 100 kPa (1.0 ton/ft2)orgreater, the compression device shall be capable of measuringthe compre
26、ssive stress to the nearest 5 kPa (0.05 ton/ft2).5.2 Sample Extruder, capable of extruding the soil corefrom the sampling tube at a uniform rate in the same directionof travel in which the sample entered the tube, and withnegligible disturbance of the sample. Conditions at the time ofsample removal
27、may dictate the direction of removal, but theprincipal concern is to reduce the potential for additionaldisturbance beyond that incurred during initial sampling.5.3 Deformation Indicator, The deformation indicator shallbe a dial indicator graduated to 0.03 mm (0.001 in.) or betterand having a travel
28、 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.5.4 Dial Comparator, or other suitable device, for measur-ing the physical dimensions of the specimen to within 0.1 % ofthe measur
29、ed dimension.NOTE 4Vernier calipers are not recommended for soft specimens,which will deform as the calipers are applied on the specimen.5.5 Timer, A timing device indicating the elapsed testingtime to the nearest second shall be used for establishing the rateof strain application prescribed in 7.1.
30、5.6 Balance, The balance used to weigh specimens shalldetermine the mass of the specimen to within 0.1 % of its totalmass.5.7 Equipment, as specified in Test Method D 2216.5.8 Miscellaneous Apparatus, including specimen trimmingand carving tools, remolding apparatus, water content cans,and data shee
31、ts, as required.6. Preparation of Test Specimens6.1 Specimen SizeSpecimens shall have a minimum di-ameter of 30 mm (1.3 in.) and the largest particle containedwithin the test specimen shall be smaller than one tenth of thespecimen diameter. For specimens having a diameter of 72 mm(2.8 in.) or larger
32、, 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 oftest da
33、ta (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 5.4. Takea minimum of three height measurements (120 apart), and atleast three diameter measurements at the quarter points of theheight.
34、NOTE 5If large soil particles are found in the specimen after testing,a particle-size analysis performed in accordance with Test Method D 6913may be performed to confirm the visual observation and the resultsprovided with the test report.6.2 Intact SpecimensPrepare intact specimens from largesamples
35、 or from samples secured in accordance with PracticeD 1587 and preserved and transported in accordance with thepractices for Group C samples in Practices D 4220. Tubespecimens may be tested without trimming except for thesquaring of ends, if conditions of the sample justify thisprocedure. Handle spe
36、cimens 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 small sections tofacilitate removal of
37、the specimen with minimal disturbance.Prepare carved specimens with minimal disturbance, andwhenever possible, in a humidity-controlled room. Make everyD 2166 062effort to prevent a change in water content of the soil.Specimens shall be of uniform circular cross section with endsperpendicular to the
38、 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 ends, cap thespecimen with a
39、 minimum thickness of plaster of paris,hydrostone, or similar material. When sample condition per-mits, a vertical lathe that will accommodate the total samplemay be used as an aid in carving the specimen to the requireddiameter. Where prevention of the development of appreciablecapillary forces is
40、deemed important, seal the specimen with arubber membrane, thin plastic coatings, or with a coating ofgrease or sprayed plastic immediately after preparation andduring the entire testing cycle. Determine the mass anddimensions of the test specimen. If the specimen is to becapped, its mass and dimens
41、ions should be determined beforecapping. If the entire test specimen is not to be used fordetermination of water content, secure a representative sampleof trimmings for this purpose, placing them immediately in acovered container. The water content determination shall beperformed in accordance with
42、Test Method D 2216.6.3 Remolded SpecimensSpecimens may be prepared ei-ther from a failed intact specimen or from a disturbed sample,providing it is representative of the failed intact specimen. Inthe case of failed intact specimens, wrap the material in a thinrubber membrane and work the material th
43、oroughly with thefingers to assure complete remolding. Avoid entrapping air inthe specimen. Exercise care to obtain a uniform density, toremold to the same void ratio as the intact specimen, and topreserve the natural water content of the soil. Form thedisturbed material into a mold of circular cros
44、s section havingdimensions meeting the requirements of 6.1. After removalfrom the mold, determine the mass and dimensions of the testspecimens.6.4 Reconstituted SpecimensSpecimens shall be preparedto the predetermined water content and density prescribed bythe individual assigning the test (Note 6).
45、 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
46、 that isgreater than 90 %.7. Procedure7.1 Place the specimen in the loading device so that it iscentered on the bottom platen. Adjust the loading devicecarefully so that the upper platen just makes contact with thespecimen. Zero the deformation indicator or record the initialreading of the electroni
47、c deformation device.Apply the load soas to produce an axial strain at a rate of12 to 2 %/min. Recordload, deformation, and time values at sufficient intervals todefine the shape of the stress-strain curve (usually 10 to 15points are sufficient). The rate of strain should be chosen so thatthe time t
48、o failure does not exceed about 15 min (Note 7).Continue loading until the load values decrease with increasingstrain, or until 15 % strain is reached. Indicate the rate of strainin the report of the test data, as required in 9.1.7. Determine thewater content of the test specimen using the entire sp
49、ecimen,unless representative trimmings are obtained for this purpose,as in the case of intact specimens. Indicate on the test reportwhether the water content sample was obtained before or afterthe shear test, as required in 9.1.2.NOTE 7Softer materials that will exhibit larger deformation at failureshould be tested at a higher rate of strain. Conversely, stiff or brittlematerials that will exhibit small deformations at failure should be tested ata lower rate of strain.7.2 Make a sketch, or take a photo, of the test specimen atfailure showing the slope angle of the fa
