1、Designation: D6528 17Standard Test Method forConsolidated Undrained Direct Simple Shear Testing of FineGrain Soils1This standard is issued under the fixed designation D6528; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、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.1. Scope*1.1 This test method defines equipment specifications andtesting procedures for the measurement of constant volumestre
3、ngth and stress-strain characteristics of cohesive soils afterone-dimensional consolidation using a constant rate of simpleshear deformation mode of loading. The constant volumecondition is equivalent to the undrained condition for saturatedspecimens.1.2 This test method is written specifically for
4、devices thattest rectangular parallelepiped or cylindrical specimens. Othermore general devices, such as the torsional shear hollowcylinder, may be used to perform consolidated constant volumesimple shear tests but are beyond the scope of this test method.1.3 This test method is applicable to testin
5、g intact, labora-tory reconstituted, and compacted soils, however, it does notinclude specific guidance for reconstituting or compacting testspecimens.1.4 It shall be the responsibility of the agency requestingthis test to specify the magnitude of the vertical consolidationstress prior to constant v
6、olume shear and, when appropriate,the maximum vertical consolidation stress, which will result inan overconsolidated specimen.1.5 UnitsThe values stated in SI units are to be regardedas the standard. No other units of measurement are included inthis standard. Reporting of test results in units other
7、 than SIshall not be regarded as nonconformance with this test method.1.5.1 In the engineering profession it is customary practiceto use, interchangeably, units representing both mass and force,unless dynamic calculations (F=Ma) are involved. This implic-itly combines two separate systems of units,
8、that is, theabsolute system and the gravimetric system. It is scientificallyundesirable to combine two separate systems within a singlestandard. This test method has been written using SI units;however, inch-pound conversions are given in the gravimetricsystem, where the pound (lbf) represents a uni
9、t of force(weight). The use of balances or scales recording pounds ofmass (lbm), or the recording of density in lb/ft3should not beregarded as nonconformance with this test method.1.6 All observed and calculated values shall conform to theguidelines for significant digits and rounding established in
10、Practice D6026.1.6.1 The procedures used to specify how data are collected/recorded or calculated in this test standard are regarded as theindustry standard. In addition, they are representative of thesignificant digits that should generally be retained. The proce-dures used do not consider material
11、 variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives; it is common practice toincrease or reduce significant digits of reported data to becommensurate with these considerations. It is beyond the scopeof this test standard to consider sig
12、nificant digits used inanalysis methods for engineering design.1.6.2 Measurements made to more significant digits orbetter sensitivity than specified in this standard shall not beregarded a nonconformance with this standard.1.7 This standard does not purport to address all of thesafety concerns, if
13、any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accor-dance with internati
14、onally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D653 Term
15、inology Relating to Soil, Rock, and ContainedFluids1This 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 Aug. 1, 2017. Published September 2017. Origina
16、llyapproved in 2000. Last previous edition approved in 2007 as D6528 07, which waswithdrawn January 2016 and reinstated in August 2017. DOI: 10.1520/D6528-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of A
17、STMStandards volume information, 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 StatesThis international standa
18、rd was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1D854 Te
19、st 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 MassD2435 Test Methods for One-Dimensional Conso
20、lidationProperties of Soils Using Incremental LoadingD2487 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classification System)D2488 Practice for Description and Identification of Soils(Visual-Manual Procedures)D3550 Practice for Thick Wall, Ring-Lined, Split Barrel,Driv
21、e Sampling of 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, andPlasticity Index
22、 of SoilsD4452 Practice for X-Ray Radiography of Soil SamplesD6026 Practice for Using Significant Digits in GeotechnicalDataD6913 Test Methods for Particle-Size Distribution (Grada-tion) of Soils Using Sieve AnalysisD7928 Test Method for Particle-Size Distribution (Grada-tion) of Fine-Grained Soils
23、Using the Sedimentation(Hydrometer) Analysis3. Terminology3.1 Definitions:3.1.1 For definitions of common technical terms used in thisstandard, refer to Terminology D653.3.2 shear modulus, na measure of a materials resistanceto shear stress, equal to the ratio of the increment in the shearstress to
24、the resultant increment in angle of deformationexpressed in radians; also known as the modulus of rigidity.3.3 Definitions of Terms Specific to This Standard:3.3.1 active height control, na method of keeping theheight of the specimen constant during the shearing process inwhich the displacement cont
25、rol mechanism is physically ad-justed in response to the vertical displacement measurement.3.3.2 passive height control, na method of keeping theheight of the specimen constant during the shearing process inwhich the specimen and force measuring device are clampedby a mechanism that is much stiffer
26、than the specimen.4. Summary of Test Method4.1 In this test method a specimen of cohesive soil isconstrained vertically between two parallel, rigid platens andlaterally, such that the cross sectional area remains constant.4.2 The specimen is loaded vertically and allowed to con-solidate one-dimensio
27、nally. Each vertical load increment ismaintained until excess pore water pressures are essentiallydissipated as interpreted from the vertical displacement rate.The maximum vertical load is maintained until completion ofone cycle of secondary compression or one day longer than theend of excess pore w
28、ater pressure dissipation.4.3 The specimen is sheared by displacing one platentangentially relative to the other at a constant rate of displace-ment and measuring the resulting shear force. The platens areconstrained against rotation and vertical movement throughoutshear.4.4 The specimen volume is h
29、eld constant during shear tosimulate undrained conditions. Constant volume is achieved bychanging the vertical load applied to the specimen to maintainconstant specimen height. Since the pore pressure is zerothrough shear, the change in vertical stress is equal to thechange in effective stress and a
30、ssumed to be equal to thechange in pore water pressure that would occur in a sealedspecimen confined by a constant vertical total stress.NOTE 1The quality of the result produced by this test standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment an
31、d facilities. Agencies that meet the criteriaof Practice D3740 generally are considered capable of competent andobjective testing/sampling/inspection/etc. Users of this test standard arecautioned that compliance with Practice D3740 does not in itself assurereliable results. Reliable results depend o
32、n many factors; Practice D3740provides a means of evaluating some of those factors.5. Significance and Use5.1 The shear strength of a specimen depends on the methodof shearing, soil type, vertical consolidation stress, time ofconsolidation, rate of strain, and prior stress history of the soil.5.2 In
33、 this test, the shear strength is measured underconstant volume conditions that are equivalent to undrainedconditions for a saturated specimen; hence, the test is appli-cable to field conditions wherein soils have fully consolidatedunder one set of stresses, and then are subjected to changes instres
34、s without time for further drainage to take place.5.3 The constant volume (undrained) strength is a functionof stress conditions. In this test method, the strength ismeasured under plane strain conditions and the principlestresses continuously rotate due to the application of shearstress. This simpl
35、e shear stress condition occurs in many fieldsituations including zones below a long embankment andaround axially loaded piles.5.4 The state of stress within the simple shear specimen isnot sufficiently defined nor uniform enough to allow rigorousinterpretation of the results. Expressing the data in
36、 terms of theshear stress and vertical effective stress on the horizontal planeis useful for engineering purposes, but should not be confusedwith the effective stress parameters derived from other sheartests having better defined states of stress.5.5 The values of the secant shear modulus can be use
37、d toestimate the initial settlements of embankments built onsaturated cohesive soils due to undrained shear deformations.5.6 The data and the rate of consolidation from the consoli-dation portion of this test are comparable to results obtainedusing Test Methods D2435 provided that the more rigorousc
38、onsolidation procedure of Test Methods D2435 is followed.D6528 1725.6.1 When using wire reinforced membranes the verticaldisplacements measured from Test Methods D2435 are some-what smaller than for the direct simple shear test because thedirect simple shear (DSS) specimens lateral confinement isles
39、s rigid.5.6.2 The estimated preconsolidation pressure is compa-rable provided the specimen is loaded sufficiently into thenormally consolidated range.6. Apparatus6.1 Fig. 1 presents a schematic diagram of the necessarycomponents for the apparatus.6.2 Vertical Loading DeviceAsuitable device for apply
40、ingvertical force to the specimen that must be capable of main-taining constant force during the consolidation phase of a test,permit quick application of force for consolidation increments,and allow continuous adjustment of force when using activeheight control or be rigidly locked in place when us
41、ing passiveheight control.6.3 Shear Loading DeviceA suitable device for applyingshear force to the specimen with sufficient capacity and controlto deform the specimen at the required displacement rate.Displacement should be smooth and continuous. At aminimum, the displacement rate should be within 6
42、15 % ofthe average calculated rate (12.3.7) from 50 % of the peakshear force to the end of the test. Vibration due to operation ofthis device should be sufficiently small so as not to causevisible ripples in a glass of water placed on the loadingplatform.6.4 Force TransducerTwo suitable transducers:
43、 one formeasuring vertical force and one for measuring shear force.Each transducer shall have the necessary capacity, be accurateto 61 % of the applied maximum force for a given test andhave a readability of at least 4 significant digits of the appliedmaximum force for a given test. The transducers
44、shall beinsensitive to eccentric loading or installed in a fashion toeliminate eccentric loading. The compressibility of the shearmeasuring transducer shall not cause the deviation in sheardisplacement rate to exceed6 15 % of the average rate. Whenusing passive height control, the compressibility of
45、 the verticaltransducer plus compressibility of slide table must satisfy thedeflection requirement of 6.9.6.5 Vertical Loading RamAsuitable device that must holdone platen parallel to the other while allowing vertical dis-placement of the specimen. If the piston resists the shear force,it must do so
46、 with negligible rotation of the platen.6.6 Shear Slide TableA suitable device that must hold theplatens parallel to each other and allow shear displacement ofthe specimen. When using passive height control device theslide tables compressibility plus the compressibility of verticaltransducer must sa
47、tisfy the deflection requirement of 6.9. Theslide table shall allow a sufficient displacement to provide aminimum of 30 % shear strain.6.7 Lateral Confinement DeviceThe specimen shall beconstrained laterally such that the cross-sectional area at anylocation does not change by more than 0.1 % during
48、shear. Inaddition, the confinement must allow uniform shear deforma-tion. Circular specimens are generally confined by a wirereinforced membrane or stacked rigid rings. Square specimensgenerally are confined by stacked hollow plates or hinged solidplates. The thickness of the individual stacked ring
49、s or platesmust be less than110 of the specimen thickness in order toallow relatively uniform shear deformation. When the confin-ing device is within a water bath, it shall be constructed ofcorrosion resistant material.6.7.1 Specimen Size Requirements:6.7.1.1 The minimum specimen diameter (or lateral dimen-sion) shall be 45 mm.6.7.1.2 The minimum specimen height shall be 12 mm.6.7.1.3 The height to diameter, or minimum lateraldimension, ratio shall not exceed 0.4.6.7.1.4 The specimen height shall not be less than ten timesthe maximum particle diameter (see 9.4).6.7.2
