ASTM D4648-00

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Designation: D 4648 – 00
Standard Test Method for
Laboratory Miniature Vane Shear Test for Saturated
Fine-Grained Clayey Soil
This standard is issued under the fixed designation D4648; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope * as used in Engineering Design and Construction
D4220 Practices for Preserving and Transporting Soil
1.1 This test method covers the miniature vane test in very
Samples
soft to stiff saturated fine-grained clayey soils (f=0). Knowl-
edge of the nature of the soil in which each vane test is to be
3. Terminology
made is necessary for assessment of the applicability and
3.1 Definitions of Terms Specific to This Standard:
interpretation of the test results.
3.1.1 torque—the product of the magnitude of a force and
NOTE 1—It is recommended that the miniature vane test be conducted
the perpendicular distance of the line of action of the force
in fine-grained, predominately clay soils with an undrained shear strength
from a specified axis of rotation.
less than 1.0 tsf (100 kPa) which are defined as stiff according to Practice
3.1.2 torque spring—an elastic spring that can be calibrated
D2488.Vanefailureconditionsinhigherstrengthclayandpredominantly
to provide a measure of torque that is proportional to the
silty soils may deviate from the assumed cylindrical failure surface,
rotation (about a central longitudinal axis) of one end of the
thereby causing error in the measured strength.
spring relative to a fixed condition at the opposite end of the
1.2 This test method includes the use of both conventional
spring.
calibrated torque spring units (MethodA) and electrical torque
3.1.3 torque transducer—an electronic measuring device
transducer units (Method B) with a motorized miniature vane
that can be calibrated to provide a measure of torque.
shear device.
1.3 Laboratory vane is an ideal tool to investigate strength
4. Summary of Test Method
anisotropy in the vertical and horizontal directions, if suitable
4.1 The miniature vane shear test consists of inserting a
samples (specimens) are available.
four-bladed vane in the end of an undisturbed tube sample or
1.4 The values stated in inch-pound units are to be regarded
remolded sample and rotating it at a constant rate to determine
as the standard. The values given in parentheses are for
the torque required to cause a cylindrical surface to be sheared
information only.
by the vane. This torque is then converted to a unit shearing
1.5 This standard does not purport to address all of the
resistance of the cylindrical surface area. The torque is mea-
safety concerns, if any, associated with its use. It is the
sured by a calibrated torque spring or torque transducer that is
responsibility of the user of this standard to establish appro-
attached directly to the vane.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
5. Significance and Use
5.1 The miniature vane shear test may be used to obtain
2. Referenced Documents
estimates of the undrained shear strength of fine-grained soils.
2.1 ASTM Standards:
Thetestprovidesarapiddeterminationoftheshearstrengthon
D1587 Practice for Thin-Walled Tube Sampling of Soils
undisturbed, or remolded or reconstituted soils.
D2488 Practice for Description and Identification of Soils
(Visual-Manual Procedure) NOTE 2—Notwithstanding the statements on precision and bias con-
tained in this test method: The precision of this test method is dependent
D2573 MethodforFieldVaneShearTestInCohesiveSoil
onthecompetenceofthepersonnelperformingitandthesuitabilityofthe
D3740 Practice for Minimum Requirements for Agencies
equipment and facilities used. Agencies that meet the criteria of Practice
Engaged in theTesting and/or Inspection of Soil and Rock
D3740 are generally considered capable of competent and objective
testing. Users of this test method are cautioned that compliance with
Practice D3740 does not in itself ensure reliable testing. Reliable testing
1 depends on several factors; Practice D3740 provides a means for
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
evaluating some of those factors.
Rock and is the direct responsibility of Subcommittee D18.13 on Marine Geotech-
nics.
Current edition approved Feb. 10, 2000. Published April 2000. Originally
published as D4648–87. Last previous edition D4648–94.
2 3
Annual Book of ASTM Standards, Vol 04.08. Annual Book of ASTM Standards, Vol 04.09.
*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.
D 4648
6. Interferences
6.1 Vane Disturbance—The remolded zone around a vane
blade resulting from insertion is generally assumed to be small
and have little or no effect on the stress-strain properties of the
sediment being tested. In reality, the volume of soil disturbed
by the insertion of the vane blade into the assumed cylindrical
volume of soil being tested may be significant. It is recom-
mended that the vane displace no more than 15% of the soil
being tested as defined by the vane area ratio presented in Fig.
1.
7. Apparatus
7.1 Vane Blade—The vane assembly shall consist of four
rectangular bladed 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) 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 Device—Thevanedeviceshouldbemotorizedand
shallrotatethetorquespringataconstantrateof60to90°/min
FIG. 2 Miniature Vane Blade Geometry
(17to26mrd/s).Thevane/springrotationdeviceshallhavean
indicator or recording system that displays/records deflection
is to vary the ratio in order to determine the horizontal and vertical
(torque) of the calibrated spring or electrical transducer and,
strengths separately. For more detailed discussion on effects of height to
where possible, vane blade rotation.
diameter ratio as well as vane shape, refer to Refs. (1) and (2).
7.3 Torque Measuring Device—The torque measuring de-
vice shall be a conventional torque spring, electrical torque
8. Preparation and Testing of Samples
transducer, or any other measuring device capable of the
8.1 Specimen Size—Specimens should have a diameter
accuracyprescribedhereinandmaybepartofthevanedevice.
sufficient to allow clearance of at least two blade diameters
Thetorquemeasuringdeviceshallbecapableofmeasuringthe
betweenallpointsonthecircumferenceoftheshearingsurface
torque to at least 2 significant digits.
and the outer edge of the sample.
NOTE 3—Since many clays are anisotropic with respect to strength, the
relative importance of horizontal, as distinct from vertical, shearing
surfaces can influence the test results. For this reason it is important that
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
therecommendedratioofheighttodiameterberespectedunlesstheintent this standard.
FIG. 1 Vane Area Ratio for ASTM Vanes
D 4648
8.2 Undisturbed Vane Strength—Prepare undisturbed speci- weights, and resulting torque shown in Fig. 3 is recommended
mens from large undisturbed samples secured in accordance for consideration in the calibration procedure.
with Practice D1587, and handle and transport in accordance
11. Application and Measurement of Vane Blade Torque
with the practices for Group C and D Samples in Practices
D4220.Testsmayberuninthesamplingtube,eliminatingthe
11.1 Apply the torque to the vane by a conventional torque
need for extrusion. Handle specimens carefully to prevent
spring (Fig. 4a) or an electrical torque transducer (Fig. 4b) that
disturbanceorlossofmoisturecontent.Trimflattheendofthe
is rotated with the vane/spring rotation device. The torque
sample where the vane will be inserted. The sample shall be
spring or transducer shall produce a repeatable linear relation-
perpendicular to the wall of the tube.
ship between spring deflection (degrees) or transducer output
8.3 Remolded Vane Strength—Conduct remolded miniature (mV) and torque applied.
vane strength tests on failed specimens similar to remolded
NOTE 6—Since vane strength may be greatly influenced by the rate at
field vane tests (Method D2573) by rotating the vane rapidly
which shear occurs, it is recommended that torque be applied using a
through a minimum of five to ten revolutions.
motorized vane device.Ahand crank manual device may be utilized, but
is not recommended due to the potential variation in rate of shear.
NOTE 4—Remolded shear strength measurements are conventionally
NOTE 7—When the miniature vane test is conducted using a calibrated
obtained by conducting strength tests on specimens encased in a thin
torquespring,thetopofthespringunitisrotatedataconstantrotationrate
rubber membrane, to prevent change in water content, and remolded by
while the bottom of the spring most often remains stationary or nearly
hand (hand remolding). Field vane remolded strength has however been
stationary until enough energy (torque) is built up in the spring. Just prior
obtained by rotating the vane rapidly through a minimum of five to ten
tooratfailure,thebottomofthespringandvanebegintorotate(generally
complete revolutions and conducting a vane test within 1 min of the
slowly) as failure begins. The torque applied by the spring soon over-
remolding process (machine remolding). A machine remolded test yields
comestheshearingresistanceofthesoilandthevanebladerotatesrapidly
a vane strength value that is considered more a residual strength. The
to bring the soil to total failure. Thus, depending upon the stiffness of the
machine remolded strength is typically higher than the hand remolded
calibrated torque spring, soil strength, and consistency, the rate of shear
strength and, as a consequence, produces lower sensitivities. In many
and possibly the shear strength may vary.
sensitive clayey soils, residual strengths may be obtained within one to
NOTE 8—It should be recognized that there is a fundamental difference
two revolutions or less. If such soils are being tested, it is recommended
in the failure modes between miniature vane tests made using a calibrated
that several remolded strengths be obtained using the standard five to ten
torque spring and an electrical transducer.An electrical torque transducer
revolutions for verification. If no major remolded strength differences are
will produce a strain-controlled failure of the soil, whereas a calibrated
noted, remolded strengths may be obtained at less than the recommended
torque spring will produce failure that varies somewhere between purely
five to ten revolutions.
stress-controlled and strain-controlled conditions. Using an electrical
NOTE 5—In cases where electrical torque transducers with wires for
torque transducer, the constant rate of rotation applied to the top of the
signaltransmissionareutilized,theremoldedminiaturevanestrengthmay
torque transducer is transmitted directly to the vane blade. The resulting
be obtained by rotating the vane one complete revolution in one direction
strain-controlled failure could result in a higher rate of shear than that
and then again in the opposite direction a number of times to produce the
produced using a calibrated torque spring.
desired five to ten complete revolutions.
12. Vane Rotation and Shearing Rate
9. Preparation of Apparatus
12.1 Apply torque to the vane/spring at a rotation rate of 60
9.1 Vane Blade Damage—Carefully check each vane prior to 90°/min (see Note 9).
to each use for bent shifts and blades and imperfections that
NOTE 9—The rate of vane rotation has two major effects on the
could alter the vane failure surface from the assumed cylindri-
cal surface.
10. Calibration
10.1 Conduct periodically calibration of the spring units (or
torque transducers) to ensure proper operation of the miniature
vane 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 known
torque(leverarmXweight).Securethevaneshearunitinsuch
a way that the vane spring (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 calibration wheel shall be noted; specifically the lever arm.
10.2 For each vane torque spring to be used, apply a series
ofcalibrationweightstothecalibrationwheeltodevelopaplot
of spring deflection (in degrees) versus torque (in lbf·in. or
N·m). Carefully fasten each calibration weight to the calibra-
tionstringandallowtodeflectthespring.Recordthedeflection
of the spring (in degrees) and applied torque for each weight
FIG. 3 Typical Calibration Wheel Configuration and Weight
applied. The calibration wheel configuration, lever arm, Selections
D 4648
FIG. 4 Vane Torque Spring and Electrical Transducer Details Geometry
resultingmeasuredvaneshearingstrength.Thefirstispreventingdrainage
of 60 to 90°/min in accordance with 12.1. Record spring
sothatatrulyundrainedshearstrengthismeasured.Thesecondresembles
deflection or torque transducer readings at least every 5° of
a viscous effect: the faster a soil is sheared the higher is its measured
rotation until the spring deflection does not increase (which is
strength. There are currently two approaches for determining the vane
considered failure) or until a maximum of 180° of rotation is
rotationandshearingrate.Theseapproachesare(1)angularshearvelocity
obtained. During the rotation of the vane, hold the vane blade
approach, and (2) Blight’s drainage approach.Amore detailed discussion
at a fixed elevation. Record the maximum torque and interme-
of these two approaches can be found in Refs. (3) and (4), respectively.
diate torque readings if required. Remove and clean the vane
13. Miniature Vane Test Procedures
blade if necessary. Secure a representative sample of the
13.1 Fasten the vane shear unit, as well as the specimen specimentodeterminethemoisturecontent.Inspectthesoilfor
inclusions such as sand and gravel and cracking of the failure
container, securely to a table or frame to prevent movement
duringatest.Insertthevaneinthesampletoaminimumdepth surface, which may influence test results. Record the findings.
equaltotwicetheheightofthevanebladetoensurethatthetop
13.3 Fo
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