ASTM D6467-99
(Test Method)Standard Test Method for Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Cohesive Soils
Standard Test Method for Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Cohesive Soils
SCOPE
1.1 This test method provides a procedure for performing a torsional ring shear test under a drained condition to determine the residual shear strength of cohesive soils. An undisturbed specimen can be used for testing. However, obtaining a natural slip surface specimen, determining the direction of field shearing, and trimming and properly aligning the usually non-horizontal shear surface in the ring shear apparatus is difficult. As a result, this test method focuses on the use of a remolded specimen.This test method is performed by deforming a presheared, remolded specimen at a controlled displacement rate until the constant minimum drained shear resistance is offered on a single shear plane determined by the configuration of the apparatus. An unlimited amount of continuous shear displacement can be achieved to obtain a residual strength condition. Generally, three or more normal stresses are applied to a test specimen to determine the drained residual failure envelope. A separate test specimen may be used for each normal stress.
1.2 A shear stress-displacement relationship may be obtained from this test method. However, a shear stress-strain relationship or any associated quantity, such as modulus, cannot be determined from this test method because possible soil extrusion and volume change prevents defining the height needed in the shear strain calculations. As a result, shear strain cannot be calculated but shear displacement can be calculated.
1.3 The selection of normal stresses and final determination of the shear strength envelope for design analyses and the criteria to interpret and evaluate the test results are the responsibility of the engineer or office requesting the test.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.4 The values stated in SI units are to be regarded as the standard. The values stated in inch-pound units are approximated.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation:D6467–99
Standard Test Method for
Torsional Ring Shear Test to Determine Drained Residual
Shear Strength of Cohesive Soils
This standard is issued under the fixed designation D 6467; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method provides a procedure for performing a 2.1 ASTM Standards:
torsional ring shear test under a drained condition to determine D 422 Test Method for Particle-Size Analysis of Soils
the residual shear strength of cohesive soils. An undisturbed D 653 Terminology Relating to Soil, Rock, and Contained
specimen can be used for testing. However, obtaining a natural Fluids
slip surface specimen, determining the direction of field D 854 Test Method for Specific Gravity of Soils
shearing, and trimming and properly aligning the usually D 2216 TestMethodforLaboratoryDeterminationofWater
non-horizontal shear surface in the ring shear apparatus is (Moisture) Content of Soil and Rock
difficult. As a result, this test method focuses on the use of a D 2435 Test Method for One-Dimensional Consolidation
remolded specimen.This test method is performed by deform- Properties of Soils
ing a presheared, remolded specimen at a controlled displace- D 2487 Classification of Soils for Engineering Purposes
ment rate until the constant minimum drained shear resistance (Unified Soil Classification System)
is offered on a single shear plane determined by the configu- D 3740 Practice for Minimum Requirements for Agencies
ration of the apparatus. An unlimited amount of continuous Engaged in the Testing and/or Inspection of Soil and Rock
shear displacement can be achieved to obtain a residual as Used in Engineering Design and Construction
strengthcondition.Generally,threeormorenormalstressesare D 4318 Test Method for Liquid Limit, Plastic Limit, and
applied to a test specimen to determine the drained residual Plasticity Index of Soils
failure envelope. A separate test specimen may be used for
3. Terminology
each normal stress.
1.2 A shear stress-displacement relationship may be ob- 3.1 Definitions—For definitions of terms used in this test
method, refer to Terminology D 653.
tained from this test method. However, a shear stress-strain
3.2 Definitions of Terms Specific to This Standard:
relationship or any associated quantity, such as modulus,
cannot be determined from this test method because possible 3.2.1 consolidated—soil specimen condition after primary
consolidation under a specific normal stress.
soil extrusion and volume change prevents defining the height
needed in the shear strain calculations.As a result, shear strain 3.2.2 presheared—soil specimen condition after shearing at
least one revolution of the ring in the direction of shear to
cannot be calculated but shear displacement can be calculated.
1.3 The selection of normal stresses and final determination create a failure surface prior to drained shearing.
3.2.3 residual shear force—the shear force being applied to
of the shear strength envelope for design analyses and the
criteria to interpret and evaluate the test results are the the specimen when the shear resistance neither increases nor
decreases with continued shear displacement.
responsibility of the engineer or office requesting the test.
1.4 This standard does not purport to address all of the 3.2.4 residual shear strength—the constant minimum resis-
tance of soil to shear along a fully developed failure surface
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- and equals the residual shear force divided by the cross-
sectional area of the specimen.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Summary of Test Method
1.5 The values stated in SI units are to be regarded as the
4.1 This test method consists of placing the specimen in the
standard. The values stated in inch-pound units are approxi-
annular specimen container, applying a predetermined normal
mated.
stress through the top loading platen, providing for wetting and
draining of the specimen (optional); consolidating the speci-
men under the normal stress; decreasing the normal stress to
This test method is under the jurisdiction of ASTM Committee D-18 on Soil
and Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
Compressibility of Soils.
Current edition approved Oct. 10, 1999. Published February 2000. Annual Book of ASTM Standards, Vol 04.08.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D6467–99
yield an overconsolidated specimen; preshearing the specimen specimen container.The frames that hold the specimen shall be
by rotating the specimen container against the top loading sufficiently rigid to prevent their distortion during shearing.
platen for one revolution; applying a constant rate of shear The various parts of the shear device shall be made of a
deformation; and measuring the shearing force and displace- material such as stainless steel, bronze, or coated aluminum
ment until a constant minimum resistance is reached. thatisnotsubjecttocorrosionbymoistureorsubstanceswithin
the soil. Dissimilar metals, which may cause galvanic action,
are not permitted.
5. Significance and Use
6.2 Specimen Container, a device containing an annular
5.1 Theapparatuskeepsthecross-sectionalareaoftheshear
cavity for the soil specimen with an inside diameter not less
surface constant during shear and shears the specimen continu-
than 50 mm (2 in.) and an inside to outside diameter ratio not
ously in one rotational direction for any magnitude of displace-
lessthan0.6.Thecontainerhasprovisionsfordrainagethrough
ment. This allows clay particles to become oriented parallel to
the top and bottom. The initial specimen depth, before con-
the direction of shear and a residual strength condition to
solidation and preshearing, is not less than 5 mm (0.2 in.). The
develop.
maximum particle size is limited to 10 % of the initial
5.2 The apparatus allows a remolded specimen to be over-
specimen height as stated in the test specimen description. Soil
consolidated and presheared prior to drained shearing. This
extrusion and changes in specimen volume during shear
simulates the field conditions that lead to a preexisting shear
preclude use of the device for undrained testing unless the
surface along which the drained residual strength can be
device can provide a constant volume or undrained condition.
mobilized.
6.3 Torque Arm/Loading Platen Assembly, may have differ-
5.3 The ring shear test is suited to the relatively rapid
ent bearing stops for the proving rings, load cells, or force or
determination of drained residual shear strength because of the
torque transducers to provide different options for the torque
short drainage path through the thin specimen, and the capa-
measurement.
bilityoftestingonespecimenunderdifferentnormalstressesto
6.4 Porous Inserts, two bronze or stainless steel porous
quickly obtain a shear strength envelope.
inserts mounted on the top loading platen and the bottom of the
5.4 The test results are primarily applicable to assess the
specimen container cavity to allow drainage from the soil
shearstrengthinslopesthatcontainapreexistingshearsurface,
specimen along the top and bottom boundaries. The inserts aid
such as old landslides, and sheared bedding planes, joints, or
in transfer of shear stress to the top and bottom boundaries of
faults.
the specimen. The inserts must be sufficiently serrated to
NOTE 1—Notwithstanding the statements on precision and bias con-
develop a strong interlock with the soil specimen. The perme-
tained in this test method: The precision of this test method is dependent
ability of the inserts shall be substantially greater than that of
on the competence of the personnel performing it and the suitability of the
the soil, but shall be textured fine enough to prevent excessive
equipment and facilities used. Agencies that meet the criteria of Practice
intrusion of the soil into the pores of the insert. The outer and
D 3740 are generally considered capable of competent testing. Users of
inner diameters of the inserts shall be 0.1 mm (0.004 in.) less,
this test method are cautioned that compliance with Practice D 3740 does
not ensure reliable testing. Reliable testing depends on several factors;
and greater than those of the specimen annular cavity, respec-
Practice D 3740 provides a means of evaluating some of those factors.
tively. The serration should have a depth of between 10 and
15 % of the initial specimen height.
6. Apparatus
NOTE 2—Exact criteria for insert texture and permeability have not
6.1 Shear Device, to hold the specimen securely between
been established. For normal soil testing, medium-grade inserts with a
two porous inserts. The shear device shall provide a means for –4 –3 3
permeability of about 5.0 3 10 to 1.0 3 10 cm/s (0.5 to 1.0 3 10
applying a normal stress to the faces of the specimen, for
ft/year) are appropriate for testing silts and clays. It is important that the
measuring changes in thickness of the specimen, for permitting
permeability of the porous insert is not reduced by the collection of soil
particles in the pores of the insert; hence frequent checking and cleaning
drainage of water through the porous inserts at the top and
(by flushing and boiling, or by ultrasonic cleaning) are required to ensure
bottom boundaries of the specimen, and for submerging the
the necessary permeability.
specimen in water. The device shall be capable of applying a
torque to the specimen along a shear plane parallel to the faces 6.5 Loading Devices:
of the specimen. A number of different ring shear devices are 6.5.1 Device for Applying and Measuring the Normal
commercially available, in practice, or are being developed so Force—Normal force is usually applied by a lever-loading
ageneraldescriptionofaringsheardeviceispresentedwithout yoke that is activated by dead weights (masses). The device
schematic diagrams. The location of the shear plane depends shall be capable of rapidly applying and maintaining the
on the configuration of the apparatus. As a result, the shear normal force to within 61 % of the specified force.
plane may be located near a soil/porous insert interface or at 6.5.2 Device for Shearing the Specimen—This device shall
the mid-height of the specimen if an upper ring can be be capable of shearing the specimen at a uniform rate of
separated from a bottom ring as is done in a direct shear box. displacement, with less than 65 % deviation. The rate to be
The device shall have low friction along the inner and outer applied depends upon the consolidation characteristics of the
walls of the specimen container developed during shearing. soil (see 9.5.1). The rate is usually maintained with an electric
Friction may be reduced by having the shear plane occur at the motor and gear box arrangement.
top of the specimen container, modifying the specimen con- 6.6 Shear Force Measurement Device, two proving rings,
tainer walls with low-friction material, or exposing the shear load cells, or a torque transducer accurate to measure a force of
plane by separating the top and bottom portions of the 0.2 N (0.05 lbf).
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D6467–99
6.7 Water Bath, container for the shear device and water 8.3 Apply increments of normal force up to the equipment
needed to inundate the specimen. limitations, and record the normal displacement indicator
6.8 Controlled High-Humidity Room—If required, for pre- reading and normal force. Remove the applied normal force in
paring the specimen, such that the water content gain or loss reverse sequence of the applied force, and record the normal
during specimen rehydration is minimized. displacement indicator readings and normal force. Plot the
6.9 Deformation Indicators, dial gage, or other suitable load-deformation relationship of the apparatus as a function of
normal load. Retain the results for future reference in deter-
device, capable of measuring the change in thickness of the
specimen, with a sensitivity of at least 0.0025 mm (0.0001 in.). mining the thickness of the test specimen and compression
within the test apparatus itself.
Etched scale on circumference of the ring base to measure the
degrees traveled, and thus the shear displacement, or other 8.4 Remove the calibration disk or plate.
methods capable of obtaining a sensitivity of at least 2°.
8.5 Calibration for the equipment load-deformation charac-
6.10 Equipment for Determination of Water Content,in teristics needs to be performed on the apparatus when first
accordance in Test Method D 2216. placed in service, or when apparatus parts are changed.
6.11 Miscellaneous Equipment, including timing device
NOTE 3—Other methods of proven accuracy for calibrating the appa-
with a second hand, site-specific, distilled or demineralized
ratus are acceptable.
water, mortar, pestle, spatulas, razor blades, straightedge, and
so forth.
9. Procedure
9.1 Assemble the specimen container.
7. Test Specimen
9.2 Preconsolidation:
7.1 The sample used for specimen preparation is to be
9.2.1 Place and secure the specimen container (containing
sufficiently large so that a ring shear specimen and specimens
the remolded specimen) into the empty water bath that is
forindexpropertytestscanbeprepared.Thespecimensmaybe
attached to the apparatus. Place the top platen with the moist
preparedinacontrolledtemperatureandhumidityenvironment
porous insert over the top of the specimen.
to minimize moisture loss or gain.
9.2.2 Place a small seating load so that the normal stress
7.2 Remolded specimens may be prepared by crushing an
applied to the specimen (from the seating load and the top
air-dried representative sample and passing it through the
platen) is approximately 3.0 kPa (0.4 psi).
appropriate sieve, for example, opening size less than or equal
9.2.3 Attach and adjust the vertical displacement measure-
to 10 % of the initial specimen height. Another technique for
ment device and obtain the initial time and vertical dis
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