1、Designation: D4648/D4648M 10D4648/D4648M 13Standard 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,
2、in the case of 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 very soft to stiff saturated
3、fine-grained clayey soils ( = 0). Knowledgeof the nature of the soil in which each vane test is to be made is necessary for assessment of the applicability and interpretationof the test results.NOTE 1It is recommended that the miniature vane test be conducted in fine-grained, predominately clay soil
4、s with an undrained shear strength lessthan 1.0 tsf 100 kPa. Vane failure conditions in higher strength clay and predominantly silty soils may deviate from the assumed cylindrical failuresurface, thereby causing error in the measured strength.1.2 This test method includes the use of both conventiona
5、l calibrated torque spring units (Method A) and electrical torquetransducer units (Method B) with a motorized miniature vane shear device.1.3 Laboratory vane is an ideal tool to investigate strength anisotropy in the vertical and horizontal directions, if suitablesamples (specimens) are available.1.
6、4 All measured and calculated values shall conform to the guidelines for significant digits and rounding established in PracticeD6026.1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents;
7、therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this
8、 standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1587 Practice for Thin-Walled Tube Sampling of Soils for Geotechnical PurposesD2488 Practice for Description and Identifica
9、tion of Soils (Visual-Manual Procedure)D2573 Test Method for Field Vane Shear Test in Cohesive SoilD3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD4220 Practices for Preserving and Transporting S
10、oil SamplesD6026 Practice for Using Significant Digits in Geotechnical Data3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 torquethe product of the magnitude of a force and the perpendicular distance of the line of action of the force from aspecified axis of rotation.1 This te
11、st method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current edition approved Oct. 1, 2010Feb. 1, 2013. Published November 2010March 2013. Originally approved in 1987. Last previous
12、edition approved in 20052010 asD4648D4648/D4648M05. DOI: 10.1520/D4648-10. 10. DOI: 10.1520/D4648_D4648M-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the stand
13、ards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accuratel
14、y, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Driv
15、e, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.2 torque springan elastic spring that can be calibrated to provide a measure of torque that is proportional to the rotation(about a central longitudinal axis) of one end of the spring relative to a fixed condition at the opposite en
16、d of the spring.3.1.3 torque transduceran electronic measuring device that can be calibrated to provide a measure of torque.4. Summary of Test Method4.1 The miniature vane shear test consists of inserting a four-bladed vane in the end of an undisturbed tube sample or remoldedsample and rotating it a
17、t a constant rate to determine the torque required to cause a cylindrical surface to be sheared by the vane.This torque is then converted to a unit shearing resistance of the cylindrical surface area. The torque is measured by a calibratedtorque spring or torque transducer that is attached directly
18、to the vane.5. Significance and Use5.1 The miniature vane shear test may be used to obtain estimates of the undrained shear strength of fine-grained soils. The testprovides a rapid determination of the shear strength on undisturbed, or remolded or reconstituted soils.NOTE 2Notwithstanding the statem
19、ents on precision and bias contained in this test method: The precision of this test method is dependent on thecompetence of the personnel performing it and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 aregenerally considered capable of comp
20、etent and objective testing. Users of this test method are cautioned that compliance with Practice D3740 does notin itself ensure reliable testing. Reliable testing depends on several factors; Practice D3740 provides a means for evaluating some of those factors.6. Interferences6.1 Vane DisturbanceTh
21、e remolded zone around a vane blade resulting from insertion is generally assumed to be small andhave little or no effect on the stress-strain properties of the sediment being tested. In reality, the volume of soil disturbed by theinsertion of the vane blade into the assumed cylindrical volume of so
22、il being tested may be significant. It is recommended that thevane displace no more than 15% of the soil being tested as defined by the vane area ratio presented in Fig. 1.7. Apparatus7.1 Vane BladeThe vane assembly shall consist of four rectangular bladed vanes, as illustrated in Fig. 2. It is reco
23、mmendedthat the height of the vane be twice the diameter (2:1), although vanes with a height equal to the diameter (1:1) also may be used(see Note 3). Vane blade diameter (D) may vary from 0.5 to 1.0 in. 12.7 to 25.4 mm.7.2 Vane DeviceThe vane device should be motorized and, in the case of a torque
24、spring device, shall rotate the torque springat a constant rate of 60 to 90/min 1.0 to 1.6 rd/min. A vane device which applies the torque directly through a stiff shaft usingan electrical transducer to measure torque shall rotate the vane at a constant rate that ranges from 20 to 30/min 0.35 to 0.52
25、rd/min. The vane/spring rotation device shall have an indicator or recording system that displays/records deflection (torque) ofthe calibrated spring or electrical transducer and, where possible, vane blade rotation.FIG. 1 Vane Area Ratio for ASTM VanesD4648/D4648M 1327.3 Torque Measuring DeviceThe
26、torque measuring device shall be a conventional torque spring, electrical torque transducer,or any other measuring device capable of the accuracy prescribed herein and may be part of the vane device. The torque measuringdevice shall be capable of measuring the torque to at least 3three significant d
27、igits.NOTE 3Since many clays are anisotropic with respect to strength, the relative importance of horizontal, as distinct from vertical, shearing surfacescan influence the test results. For this reason it is important that the recommended ratio of height to diameter be respected unless the intent is
28、 to varythe ratio in order to determine the horizontal and vertical strengths separately. For more detailed discussion on effects of height to diameter ratio as wellas vane shape, refer to Refs. (1) and (2).38. Preparation and Testing of Samples8.1 Specimen SizeSpecimens should have a diameter suffi
29、cient to allow clearance of at least two blade diameters between allpoints on the circumference of the shearing surface and the outer edge of the sample.8.2 Undisturbed Vane StrengthPrepare undisturbed specimens from large undisturbed samples secured in accordance withPractice D1587, and handle and
30、transport in accordance with the practices for Group C and D Samples in Practices D4220. Testsmay be run in the sampling tube, eliminating the need for extrusion. Handle specimens carefully to prevent disturbance or loss ofmoisture content. Trim flat the end of the sample where the vane will be inse
31、rted. The sample shall be perpendicular to the wallof the tube.8.3 Remolded Vane StrengthConduct remolded miniature vane strength tests on failed specimens similar to remolded fieldvane tests (Test Method D2573) by rotating the vane rapidly through a minimum of five to ten revolutions.NOTE 4Remolded
32、 shear strength measurements are conventionally obtained by conducting strength tests on specimens encased in a thin rubbermembrane, to prevent change in water content, and remolded by hand (hand remolding). Field vane remolded strength has however been obtained byrotating the vane rapidly through a
33、 minimum of five to ten complete revolutions and conducting a vane test within 1 min of the remolding process(machine remolding). A machine remolded test yields a vane strength value that is considered more a residual strength. The machine remolded strengthis typically higher than the hand remolded
34、strength and, as a consequence, produces lower sensitivities. In many sensitive clayey soils, residual strengthsmay be obtained within one to two revolutions or less. If such soils are being tested, it is recommended that several remolded strengths be obtained usingthe standard five to ten revolutio
35、ns for verification. If no major remolded strength differences are noted, remolded strengths may be obtained at less thanthe recommended five to ten revolutions.NOTE 5In cases where electrical torque transducers with wires for signal transmission are utilized, the remolded miniature vane strength ma
36、y beobtained by rotating the vane one complete revolution in one direction and then again in the opposite direction a number of times to produce the desiredfive to ten complete revolutions.9. Preparation of Apparatus9.1 Vane Blade DamageCarefully check each vane prior to each use for bent shafts and
37、 blades and imperfections that couldalter the vane failure surface from the assumed cylindrical surface.3 The boldface numbers in parentheses refer to the list of references at the end of this standard.FIG. 2 Miniature Vane Blade GeometryD4648/D4648M 13310. Calibration10.1 Conduct periodically calib
38、ration of the spring units (or torque transducers) to ensure proper operation of the miniature vanedevice and repeatability of the torque spring or transducers. Calibration is accomplished by the application of calibrated weightsonto a calibrated wheel to produce a known torque (lever arm X weight).
39、 Secure the vane shear unit in such a way that the vanespring (torque unit) is in a horizontal position. Then insert the calibration wheel in place of the vane blade. The calibration wheel,calibration string, and calibration weights all shall hang free of any obstructions. Dimensions of the calibrat
40、ion wheel shall benoted; specifically the lever arm.10.2 For each vane torque spring to be used, apply a series of calibration weights to the calibration wheel to develop a plot ofspring deflection (in degrees) versus torque (in lbfin. or Nm). Carefully fasten each calibration weight to the calibrat
41、ion stringand allow to deflect the spring. Record the deflection of the spring (in degrees) and applied torque for each weight applied. Thecalibration wheel configuration, lever arm, weights, and resulting torque shown in Fig. 3 is recommended for consideration in thecalibration procedure.11. Applic
42、ation and Measurement of Vane Blade Torque11.1 Apply the torque to the vane by a conventional torque spring (Fig. 4a) or an electrical torque transducer (Fig. 4b) that isrotated with the vane/spring rotation device. The torque spring or transducer shall produce a repeatable linear relationship betwe
43、enspring deflection (degrees) or transducer output (mV) and torque applied.NOTE 6Since vane strength may be greatly influenced by the rate at which shear occurs, it is recommended that torque be applied using a motorizedvane device. A hand crank manual device may be utilized, but is not recommended
44、due to the potential variation in rate of shear.NOTE 7When the miniature vane test is conducted using a calibrated torque spring, the top of the spring unit is rotated at a constant rotation ratewhile the bottom of the spring most often remains stationary or nearly stationary until enough energy (to
45、rque) is built up in the spring. Just prior to orat failure, the bottom of the spring and vane begin to rotate (generally slowly) as failure begins. The torque applied by the spring soon overcomes theshearing resistance of the soil and the vane blade rotates rapidly to bring the soil to total failur
46、e. Thus, depending upon the stiffness of the calibrated torquespring, soil strength, and consistency, the rate of shear and possibly the shear strength may vary.NOTE 8It should be recognized that there is a fundamental difference in the failure modes between miniature vane tests made using a calibra
47、ted torquespring and an electrical transducer. An electrical torque transducer will produce a strain-controlled failure of the soil, whereas a calibrated torque springwill produce failure that varies somewhere between purely stress-controlled and strain-controlled conditions. Using an electrical tor
48、que transducer, theconstant rate of rotation applied to the top of the torque transducer is transmitted directly to the vane blade. The resulting strain-controlled failure couldresult in a higher rate of shear than that produced using a calibrated torque spring.12. Vane Rotation and Shearing Rate12.
49、1 Apply torque to the vane/spring at a constant rate within the ranges identified in 7.2. Select the combination of torquespring or vane rotation rates to cause specimen to reach failure within 2 to 3 min (see Note 9).NOTE 9The rate of vane rotation has two major effects on the resulting measured vane shearing strength. The first is preventing drainage so that atruly undrained shear strength is measured. The second resembles a viscous effect: the faster a soil is sheared the higher is its measured strength. Thereare currently two approaches fo
