ASTM D4648-2005 Standard Test Method for Laboratory Miniature Vane Shear Test for SaturatedFine-Grained Clayey Soil《饱和细粒粘性土壤的实验室小型十字板剪切试验的标准试验方法》.pdf

《ASTM D4648-2005 Standard Test Method for Laboratory Miniature Vane Shear Test for SaturatedFine-Grained Clayey Soil《饱和细粒粘性土壤的实验室小型十字板剪切试验的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM D4648-2005 Standard Test Method for Laboratory Miniature Vane Shear Test for SaturatedFine-Grained Clayey Soil《饱和细粒粘性土壤的实验室小型十字板剪切试验的标准试验方法》.pdf（7页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D 4648 05Standard Test Method forLaboratory Miniature Vane Shear Test for SaturatedFine-Grained Clayey Soil1This standard is issued under the fixed designation D 4648; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th

2、e year of last revision. A 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 miniature vane test in verysoft to stiff saturated fine-grained clayey soils (

3、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 undrained shear

4、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 torque spring

5、 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 The values stated in inch-

6、pound units are to be regardedas the standard. The values given in parentheses are forinformation only. All measured and calculated values shallconform to the guidelines for significant digits and roundingestablished in Practice D 6026.1.5 This standard does not purport to address all of thesafety c

7、oncerns, 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 1587 Practice for Thin-Walled Tube

8、 Sampling of SoilsD 2573 Method for Field Vane Shear Test In Cohesive SoilD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas used in Engineering Design and ConstructionD 4220 Practices for Preserving and Transporting SoilSamplesD 6026 Pra

9、ctice for Using Significant Digits in Geotechni-cal Data3. 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

10、 spring 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 p

11、rovide a 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 shearedby t

12、he vane. This torque is then converted to a unit shearingresistance of the cylindrical surface area. The torque is mea-sured by a calibrated torque 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

13、 of the undrained shear strength of fine-grained soils.The test provides a rapid determination of the shear strength onundisturbed, or remolded or reconstituted soils.NOTE 2Notwithstanding the statements on precision and bias con-tained in this test method: The precision of this test method is depen

14、denton the competence of the personnel performing it and the suitability of theequipment and facilities used. Agencies that meet the criteria of PracticeD 3740 are generally considered capable of competent and objectivetesting. Users of this test method are cautioned that compliance withPractice D 3

15、740 does not in itself ensure reliable testing. Reliable testing1This 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 June 1, 2005. Published July 2005.

16、 Originally approvedin 1987. Last previous edition approved in 2000 as D 4648 00.2For 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

17、 onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.depends on several factors; Practice D 3740 provides a means forevaluating some of those factors.6.

18、 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 blade into th

19、e 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 bladed vanes, as i

20、llustrated 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 should be motor

21、ized andshall rotate the torque spring at a constant rate of 60 to 90/min(17 to 26 m rd/s). The vane/spring rotation device shall have anindicator or recording system that displays/records deflection(torque) of the calibrated spring or electrical transducer and,where possible, vane blade rotation.7.

22、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 device shall be capable of measuring thetorque to a

23、t least 2 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 recommended ratio of height to diameter be respected

24、 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 Testing of Samples8.1 Specimen SizeSpecimens should h

25、ave a diametersufficient to allow clearance of at least two blade diameters3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.FIG. 1 Vane Area Ratio for ASTM VanesFIG. 2 Miniature Vane Blade GeometryD4648052between all points on the circumference of the s

26、hearing surfaceand the outer edge of the sample.8.2 Undisturbed Vane StrengthPrepare undisturbed speci-mens from large undisturbed samples secured in accordancewith Practice D 1587, and handle and transport in accordancewith the practices for Group C and D Samples in PracticesD 4220. Tests may be ru

27、n in the sampling tube, eliminating theneed for extrusion. Handle specimens carefully to preventdisturbance or loss of moisture content. 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

28、 miniaturevane strength tests on failed specimens similar to remoldedfield vane tests (Method D 2573) by rotating the vane rapidlythrough a minimum of five to ten revolutions.NOTE 4Remolded shear strength measurements are conventionallyobtained by conducting strength tests on specimens encased in a

29、thinrubber membrane, to prevent change in water content, and remolded byhand (hand remolding). Field vane remolded strength has 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 (mach

30、ine remolding). A machine remolded test yieldsa vane strength value that is considered more a residual strength. Themachine remolded strength is typically higher than the hand remoldedstrength and, as a consequence, produces lower sensitivities. In manysensitive clayey soils, residual strengths may

31、be obtained within one totwo revolutions or less. If such soils are being tested, it is recommendedthat several remolded strengths be obtained using the standard five to tenrevolutions for verification. If no major remolded strength differences arenoted, remolded strengths may be obtained at less th

32、an the recommendedfive to ten revolutions.NOTE 5In cases where electrical torque transducers with wires forsignal transmission 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 num

33、ber of times to produce thedesired five to ten complete revolutions.9. Preparation of Apparatus9.1 Vane Blade DamageCarefully check each vane priorto each use for bent shifts and blades and imperfections thatcould alter the vane failure surface from the assumed cylindri-cal surface.10. Calibration10

34、.1 Conduct periodically calibration of the spring units (ortorque transducers) to ensure proper operation of the miniaturevane 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 kno

35、wntorque (lever arm X weight). Secure the vane shear unit in sucha way that the vane spring (torque unit) is in a horizontalposition. Then insert the calibration wheel in place of the vaneblade. The calibration wheel, calibration string, and calibrationweights all shall hang free of any obstructions

36、. Dimensions ofthe calibration wheel shall be noted; specifically the lever arm.10.2 For each vane torque spring to be used, apply a seriesof calibration weights to the calibration wheel to develop a plotof spring deflection (in degrees) versus torque (in lbfin. orNm). Carefully fasten each calibrat

37、ion weight to the calibra-tion string and allow to deflect the spring. Record the deflectionof the spring (in degrees) and applied torque for each weightapplied. The calibration wheel configuration, lever arm,weights, and resulting torque shown in Fig. 3 is recommendedfor consideration in the calibr

38、ation procedure.11. Application and Measurement of Vane Blade Torque11.1 Apply the torque to the vane by a conventional torquespring (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 l

39、inear relation-ship between spring deflection (degrees) or transducer output(mV) and torque applied.NOTE 6Since vane strength may be greatly influenced by the rate atwhich shear occurs, it is recommended that torque be applied using amotorized vane device. A hand crank manual device may be utilized,

40、 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 most often remains stationary or nearlystationary un

41、til 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 soil and the vane blade rotates rapidlyto bring the

42、 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 differencein the failure modes between miniature vane tests m

43、ade 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-controlled and strain-controlled conditions. Using

44、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 using a calibrated torque spring.12. Vane Rotation and S

45、hearing Rate12.1 Apply torque to the vane/spring at a rotation rate of 60to 90/min (see Note 9).FIG. 3 Typical Calibration Wheel Configuration and WeightSelectionsD4648053NOTE 9The rate of vane rotation has two major effects on theresulting measured vane shearing strength. The first is preventing dr

46、ainageso 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 approaches for determining the vanerotation and shearing rate. These approaches are (1) angular shear velocityapp

47、roach, 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 te

48、st. 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 embedded at least one vane blade heightbelow the sample surface (see Note 10).NOTE 10If a very long shaped vane (12 in. (305 mm) is employed totest within a samp

49、le, then the adhesion between the shaft and the soil mustbe evaluated. The adhesion is evaluated by inserting a shaft, without thevane, having the same dimensions as the actual vane shaft, into the soil tothe level to be tested and noting the resulting torque versus rotation. Thetorque is subtracted from actual test results. To eliminate this correction,the actual torque shaft can be encased in a frictionless sleeve to preventadhesion from occurring.13.2 Take an initial reading. Hold the sample firmly toprevent rotation. Initiate mechanically rotation of th