Standard Test Method for Torsional Ring Shear Test to Determine Drained Fully Softened Shear Strength and Nonlinear Strength Envelope of Cohesive Soils (Using Normally Consolidated Specimen) for Slopes with No Preexisting Shear Surfaces

SIGNIFICANCE AND USE
The ring shear apparatus maintains the cross-sectional area of the shear surface constant during shear and shears the specimen continuously in one rotational direction for any magnitude of displacement and along entire cross-sectional area.
The ring shear apparatus allows a reconstituted specimen to be consolidated at the desired normal stress prior to drained shearing. This simulates the field conditions under which the fully softened strength develops in overconsolidated clays, claystones, mudstones, and shales because the fully softened strength corresponds to the peak shear strength of a normally consolidated clay.  
The ring shear test is suited to the relatively rapid determination of drained fully softened shear strength because of the short drainage path through the thin specimen and failure occurring near the top porous stone.  
The ring shear test minimizes the effect of initial disturbance that may result from adjusting/creating a gap before starting shearing, especially in the direct shear device.
The test results are primarily applicable to assess the shear strength of overconsolidated soils for drained analysis in slopes that do not have a pre-existing shear surface, sheared bedding planes, joints, or faults.  
Note 1—Notwithstanding the statements on precision and bias contained in this test method: The precision of this test method is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent testing. Users of this test method are cautioned that compliance with Practice D3740 does not ensure reliable testing. Reliable testing depends on several factors; Practice D3740 provides a means of evaluating some of those factors.
SCOPE
1.1 This test method provides a procedure for performing a torsional ring shear test under a drained condition to determine the fully softened shear strength and nonlinear strength envelope of cohesive soils. The fully softened strength is used to evaluate the stability of slopes that do not have a preexisting shear surface. In addition, the fully softened shear strength corresponds to the peak shear strength of a normally consolidated specimen. This test method focuses on the use of a reconstituted specimen to measure the fully softened strength. This test method is performed by shearing a normally consolidated, reconstituted specimen at a controlled displacement rate until the peak shear resistance has been obtained. Generally, the drained fully softened failure envelope is determined at three or more effective normal stresses. A separate test specimen must be used for each normal stress to measure the fully softened strength otherwise a post-peak or even residual strength will be measured if the same specimen is used because of the existence of a shear surface.
1.2 The ring shear apparatus allows a reconstituted specimen to be normally consolidated at the desired normal stress prior to drained shearing. This simulates the field conditions under which the fully softened strength develops in overconsolidated clays, claystones, mudstones, and shales.
1.3 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.
1.4 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.
1.5 The values stated in SI units are to be regarded as the standard. The values gi...

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ASTM D7608-10 - Standard Test Method for Torsional Ring Shear Test to Determine Drained Fully Softened Shear Strength and Nonlinear Strength Envelope of Cohesive Soils (Using Normally Consolidated Specimen) for Slopes with No Preexisting Shear Surfaces
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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: D7608 − 10
Standard Test Method for
Torsional Ring Shear Test to Determine Drained Fully
Softened Shear Strength and Nonlinear Strength Envelope
of Cohesive Soils (Using Normally Consolidated Specimen)
1
for Slopes with No Preexisting Shear Surfaces
This standard is issued under the fixed designation D7608; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope criteria to interpret and evaluate the test results are the
responsibility of the engineer or office requesting the test.
1.1 This test method provides a procedure for performing a
torsional ring shear test under a drained condition to determine 1.5 The values stated in SI units are to be regarded as the
the fully softened shear strength and nonlinear strength enve- standard. The values given in parentheses are mathematical
lope of cohesive soils. The fully softened strength is used to conversions to inch-pound units that are provided for informa-
evaluate the stability of slopes that do not have a preexisting tion only and are not considered standard.
shear surface. In addition, the fully softened shear strength
1.6 This standard does not purport to address all of the
corresponds to the peak shear strength of a normally consoli-
safety concerns, if any, associated with its use. It is the
dated specimen. This test method focuses on the use of a
responsibility of the user of this standard to establish appro-
reconstituted specimen to measure the fully softened strength.
priate safety and health practices and determine the applica-
This test method is performed by shearing a normally
bility of regulatory limitations prior to use.
consolidated, reconstituted specimen at a controlled displace-
ment rate until the peak shear resistance has been obtained.
2. Referenced Documents
Generally, the drained fully softened failure envelope is deter-
2
2.1 ASTM Standards:
minedatthreeormoreeffectivenormalstresses.Aseparatetest
D422Test Method for Particle-Size Analysis of Soils
specimen must be used for each normal stress to measure the
D653Terminology Relating to Soil, Rock, and Contained
fully softened strength otherwise a post-peak or even residual
Fluids
strengthwillbemeasuredifthesamespecimenisusedbecause
D854Test Methods for Specific Gravity of Soil Solids by
of the existence of a shear surface.
Water Pycnometer
1.2 The ring shear apparatus allows a reconstituted speci-
D2216Test Methods for Laboratory Determination ofWater
men to be normally consolidated at the desired normal stress
(Moisture) Content of Soil and Rock by Mass
prior to drained shearing. This simulates the field conditions
D2435Test Methods for One-Dimensional Consolidation
under which the fully softened strength develops in overcon-
Properties of Soils Using Incremental Loading
solidated clays, claystones, mudstones, and shales.
D2487Practice for Classification of Soils for Engineering
Purposes (Unified Soil Classification System)
1.3 A shear stress-displacement relationship may be ob-
D3740Practice for Minimum Requirements for Agencies
tained from this test method. However, a shear stress-strain
Engaged in Testing and/or Inspection of Soil and Rock as
relationship or any associated quantity, such as modulus,
Used in Engineering Design and Construction
cannot be determined from this test method because possible
D4318Test Methods for Liquid Limit, Plastic Limit, and
soil extrusion and volume change prevents defining the height
Plasticity Index of Soils
needed in the shear strain calculations.As a result, shear strain
D6026Practice for Using Significant Digits in Geotechnical
cannot be calculated but shear displacement can be calculated.
Data
1.4 The selection of normal stresses and final determination
D6467Test Method for Torsional Ring Shear Test to Deter-
of the shear strength envelope for design analyses and the
mine Drained Residual Shear Strength of Cohesive Soils
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
2
Rock and is the direct responsibility of Subcommittee D18.05 on Strength and For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Compressibility of Soils. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved May 15, 2010. Published July 2010. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D7608–10. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7608 − 10
D3740 are generally considered capable
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