1、Designation: D4648/D4648M 10Standard Test Method forLaboratory Miniature Vane Shear Test for SaturatedFine-Grained Clayey Soil1This standard is issued under the fixed designation D4648/D4648M; the number immediately following the designation indicates theyear of original adoption or, in the case of
2、revision, the year of last 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 miniature vane test in verysoft to stiff saturated fine-grained cla
3、yey soils (f = 0). Knowl-edge of the nature of the soil in which each vane test is to bemade is necessary for assessment of the applicability andinterpretation of the test results.NOTE 1It is recommended that the miniature vane test be conductedin fine-grained, predominately clay soils with an undra
4、ined shear strengthless than 1.0 tsf 100 kPa. Vane failure conditions in higher strength clayand predominantly silty soils may deviate from the assumed cylindricalfailure surface, thereby causing error in the measured strength.1.2 This test method includes the use of both conventionalcalibrated torq
5、ue spring units (Method A) and electrical torquetransducer units (Method B) with a motorized miniature vaneshear device.1.3 Laboratory vane is an ideal tool to investigate strengthanisotropy in the vertical and horizontal directions, if suitablesamples (specimens) are available.1.4 All measured and
6、calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem
7、 shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.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 a
8、ppro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1587 Practice for Thin-Walled Tube Sampling of Soils forGeotechnical PurposesD2488 Practice for Description and Identification of Soils(Visual-M
9、anual Procedure)D2573 Test Method for Field Vane Shear Test in CohesiveSoilD3740 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 SoilSamplesD6026 Practice
10、for Using Significant Digits in GeotechnicalData3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 torquethe product of the magnitude of a force andthe perpendicular distance of the line of action of the forcefrom a specified axis of rotation.3.1.2 torque springan elastic spring
11、that can be calibratedto provide a measure of torque that is proportional to therotation (about a central longitudinal axis) of one end of thespring relative to a fixed condition at the opposite end of thespring.3.1.3 torque transduceran electronic measuring devicethat can be calibrated to provide a
12、 measure of torque.4. Summary of Test Method4.1 The miniature vane shear test consists of inserting afour-bladed vane in the end of an undisturbed tube sample orremolded sample and rotating it at a constant rate to determinethe torque required to cause a cylindrical surface to be sheared1This test m
13、ethod 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 Oct. 1, 2010. Published November 2010. Originallyapproved in 1987. Last previous edition approved in 2005 as D
14、464805. DOI:10.1520/D4648-10.2For 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 a
15、ppears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.by the vane. This torque is then converted to a unit shearingresistance of the cylindrical surface area. The torque is mea-sured by a calibrated torque
16、 spring or torque transducer that isattached directly to the vane.5. Significance and Use5.1 The miniature vane shear test may be used to obtainestimates of the undrained shear strength of fine-grained soils.The test provides a rapid determination of the shear strength onundisturbed, or remolded or
17、reconstituted soils.NOTE 2Notwithstanding the statements on precision and bias con-tained in this test method: The precision of this test method is dependenton the competence of the personnel performing it and the suitability of theequipment and facilities used. Agencies that meet the criteria of Pr
18、acticeD3740 are generally considered capable of competent and objectivetesting. Users of this test method are cautioned that compliance withPractice D3740 does not in itself ensure reliable testing. Reliable testingdepends on several factors; Practice D3740 provides a means forevaluating some of tho
19、se factors.6. Interferences6.1 Vane DisturbanceThe remolded zone around a vaneblade resulting from insertion is generally assumed to be smalland have little or no effect on the stress-strain properties of thesediment being tested. In reality, the volume of soil disturbedby the insertion of the vane
20、blade into the assumed cylindricalvolume of soil being tested may be significant. It is recom-mended that the vane displace no more than 15% of the soilbeing tested as defined by the vane area ratio presented in Fig.1.7. Apparatus7.1 Vane BladeThe vane assembly shall consist of fourrectangular blade
21、d vanes, as illustrated in Fig. 2. It is recom-mended that the height of the vane be twice the diameter (2:1),although vanes with a height equal to the diameter (1:1) alsomay be used (see Note 3). Vane blade diameter (D) may varyfrom 0.5 to 1.0 in. 12.7 to 25.4 mm.7.2 Vane DeviceThe vane device shou
22、ld be motorizedand, in the case of a torque spring device, shall rotate the torquespring at a constant rate of 60 to 90/min 1.0 to 1.6 rd/min.Avane device which applies the torque directly through a stiffshaft using an electrical transducer to measure torque shallrotate the vane at a constant rate t
23、hat ranges from 20 to 30/min0.35 to 0.52 rd/min. The vane/spring rotation device shallhave an indicator or recording system that displays/recordsFIG. 1 Vane Area Ratio for ASTM VanesFIG. 2 Miniature Vane Blade GeometryD4648/D4648M 102deflection (torque) of the calibrated spring or electrical trans-d
24、ucer and, where possible, vane blade rotation.7.3 Torque Measuring DeviceThe torque measuring de-vice shall be a conventional torque spring, electrical torquetransducer, or any other measuring device capable of theaccuracy prescribed herein and may be part of the vane device.The torque measuring dev
25、ice shall be capable of measuring thetorque to at least 3 significant digits.NOTE 3Since many clays are anisotropic with respect to strength, therelative importance of horizontal, as distinct from vertical, shearingsurfaces can influence the test results. For this reason it is important thatthe reco
26、mmended ratio of height to diameter be respected unless the intentis to vary the ratio in order to determine the horizontal and verticalstrengths separately. For more detailed discussion on effects of height todiameter ratio as well as vane shape, refer to Refs. (1) and (2).38. Preparation and Testi
27、ng of Samples8.1 Specimen SizeSpecimens should have a diametersufficient to allow clearance of at least two blade diametersbetween all points on the circumference of the shearing surfaceand the outer edge of the sample.8.2 Undisturbed Vane StrengthPrepare undisturbed speci-mens from large undisturbe
28、d samples secured in accordancewith Practice D1587, and handle and transport in accordancewith the practices for Group C and D Samples in PracticesD4220. Tests may be run in the sampling tube, eliminating theneed for extrusion. Handle specimens carefully to preventdisturbance or loss of moisture con
29、tent. Trim flat the end of thesample where the vane will be inserted. The sample shall beperpendicular to the wall of the tube.8.3 Remolded Vane StrengthConduct remolded miniaturevane strength tests on failed specimens similar to remoldedfield vane tests (Test Method D2573) by rotating the vanerapid
30、ly through a minimum of five to ten revolutions.NOTE 4Remolded shear strength measurements are conventionallyobtained by conducting strength tests on specimens encased in a thinrubber membrane, to prevent change in water content, and remolded byhand (hand remolding). Field vane remolded strength has
31、 however beenobtained by rotating the vane rapidly through a minimum of five to tencomplete revolutions and conducting a vane test within 1 min of theremolding process (machine remolding). A machine remolded test yieldsa vane strength value that is considered more a residual strength. Themachine rem
32、olded strength is typically higher than the hand remoldedstrength and, as a consequence, produces lower sensitivities. In manysensitive clayey soils, residual strengths may be obtained within one totwo revolutions or less. If such soils are being tested, it is recommendedthat several remolded streng
33、ths be obtained using the standard five to tenrevolutions for verification. If no major remolded strength differences arenoted, remolded strengths may be obtained at less than the recommendedfive to ten revolutions.NOTE 5In cases where electrical torque transducers with wires forsignal transmission
34、are utilized, the remolded miniature vane strength maybe obtained by rotating the vane one complete revolution in one directionand then again in the opposite direction a number of times to produce thedesired five to ten complete revolutions.9. Preparation of Apparatus9.1 Vane Blade DamageCarefully c
35、heck each vane priorto each use for bent shafts and blades and imperfections thatcould alter the vane failure surface from the assumed cylindri-cal surface.10. Calibration10.1 Conduct periodically calibration of the spring units (ortorque transducers) to ensure proper operation of the miniaturevane
36、device and repeatability of the torque spring or transduc-ers. Calibration is accomplished by the application of cali-brated weights onto a calibrated wheel to produce a knowntorque (lever arm X weight). Secure the vane shear unit in sucha way that the vane spring (torque unit) is in a horizontalpos
37、ition. Then insert the calibration wheel in place of the vaneblade. The calibration wheel, calibration string, and calibrationweights all shall hang free of any obstructions. Dimensions ofthe calibration wheel shall be noted; specifically the lever arm.10.2 For each vane torque spring to be used, ap
38、ply a seriesof calibration weights to the calibration wheel to develop a plotof spring deflection (in degrees) versus torque (in lbfin. orNm). Carefully fasten each calibration weight to the calibra-tion string and allow to deflect the spring. Record the deflectionof the spring (in degrees) and appl
39、ied torque for each weightapplied. The calibration wheel configuration, lever arm,weights, and resulting torque shown in Fig. 3 is recommendedfor consideration in the calibration procedure.11. Application and Measurement of Vane Blade Torque11.1 Apply the torque to the vane by a conventional torques
40、pring (Fig. 4a) or an electrical torque transducer (Fig. 4b) thatis rotated with the vane/spring rotation device. The torquespring or transducer shall produce a repeatable linear relation-ship between spring deflection (degrees) or transducer output(mV) and torque applied.NOTE 6Since vane strength m
41、ay be greatly influenced by the rate at3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.FIG. 3 Typical Calibration Wheel Configuration and WeightSelectionsD4648/D4648M 103which shear occurs, it is recommended that torque be applied using amotorized vane
42、 device. A hand crank manual device may be utilized, butis not recommended due to the potential variation in rate of shear.NOTE 7When the miniature vane test is conducted using a calibratedtorque spring, the top of the spring unit is rotated at a constant rotation ratewhile the bottom of the spring
43、most often remains stationary or nearlystationary until enough energy (torque) is built up in the spring. Just priorto or at failure, the bottom of the spring and vane begin to rotate (generallyslowly) as failure begins. The torque applied by the spring soon over-comes the shearing resistance of the
44、 soil and the vane blade rotates rapidlyto bring the soil to total failure. Thus, depending upon the stiffness of thecalibrated torque spring, soil strength, and consistency, the rate of shearand possibly the shear strength may vary.NOTE 8It should be recognized that there is a fundamental differenc
45、ein the failure modes between miniature vane tests made using a calibratedtorque spring and an electrical transducer. An electrical torque transducerwill produce a strain-controlled failure of the soil, whereas a calibratedtorque spring will produce failure that varies somewhere between purelystress
46、-controlled and strain-controlled conditions. Using an electricaltorque transducer, the constant rate of rotation applied to the top of thetorque transducer is transmitted directly to the vane blade. The resultingstrain-controlled failure could result in a higher rate of shear than thatproduced usin
47、g a calibrated torque spring.12. Vane Rotation and Shearing Rate12.1 Apply torque to the vane/spring at a constant ratewithin the ranges identified in 7.2. Select the combination oftorque spring or vane rotation rates to cause specimen to reachfailure within 2 to 3 min (see Note 9).NOTE 9The rate of
48、 vane rotation has two major effects on theresulting measured vane shearing strength. The first is preventing drainageso that a truly undrained shear strength is measured. The second resemblesa viscous effect: the faster a soil is sheared the higher is its measuredstrength. There are currently two a
49、pproaches for determining the vanerotation and shearing rate. These approaches are (1) angular shear velocityapproach, and (2) Blights drainage approach. A more detailed discussionof these two approaches can be found in Refs. (3) and (4), respectively.13. Miniature Vane Test Procedures13.1 Fasten the vane shear unit, as well as the specimencontainer, securely to a table or frame to prevent movementduring a test. Insert the vane in the sample to a minimum depthequal to twice the height of the vane blade to ensure that the topof the vane blade is em
