Standard Test Method for Consolidated Undrained Direct Simple Shear Testing of Fine Grain Soils

SIGNIFICANCE AND USE
5.1 The shear strength of a specimen depends on the method of shearing, soil type, vertical consolidation stress, time of consolidation, rate of strain, and prior stress history of the soil.  
5.2 In this test, the shear strength is measured under constant volume conditions that are equivalent to undrained conditions for a saturated specimen; hence, the test is applicable to field conditions wherein soils have fully consolidated under one set of stresses, and then are subjected to changes in stress without time for further drainage to take place.  
5.3 The constant volume (undrained) strength is a function of stress conditions. In this test method, the strength is measured under plane strain conditions and the principle stresses continuously rotate due to the application of shear stress. This simple shear stress condition occurs in many field situations including zones below a long embankment and around axially loaded piles.  
5.4 The state of stress within the simple shear specimen is not sufficiently defined nor uniform enough to allow rigorous interpretation of the results. Expressing the data in terms of the shear stress and vertical effective stress on the horizontal plane is useful for engineering purposes, but should not be confused with the effective stress parameters derived from other shear tests having better defined states of stress.  
5.5 The values of the secant shear modulus can be used to estimate the initial settlements of embankments built on saturated cohesive soils due to undrained shear deformations.  
5.6 The data and the rate of consolidation from the consolidation portion of this test are comparable to results obtained using Test Methods D2435 provided that the more rigorous consolidation procedure of Test Methods D2435 is followed.  
5.6.1 When using wire reinforced membranes the vertical displacements measured from Test Methods D2435 are somewhat smaller than for the direct simple shear test because the direct simple shear (DSS) speci...
SCOPE
1.1 This test method defines equipment specifications and testing procedures for the measurement of constant volume strength and stress-strain characteristics of cohesive soils after one-dimensional consolidation using a constant rate of simple shear deformation mode of loading. The constant volume condition is equivalent to the undrained condition for saturated specimens.  
1.2 This test method is written specifically for devices that test rectangular parallelepiped or cylindrical specimens. Other more general devices, such as the torsional shear hollow cylinder, may be used to perform consolidated constant volume simple shear tests but are beyond the scope of this test method.  
1.3 This test method is applicable to testing intact, laboratory reconstituted, and compacted soils, however, it does not include specific guidance for reconstituting or compacting test specimens.  
1.4 It shall be the responsibility of the agency requesting this test to specify the magnitude of the vertical consolidation stress prior to constant volume shear and, when appropriate, the maximum vertical consolidation stress, which will result in an overconsolidated specimen.  
1.5 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this test method.  
1.5.1 In the engineering profession it is customary practice to use, interchangeably, units representing both mass and force, unless dynamic calculations (F=Ma) are involved. This implicitly combines two separate systems of units, that is, the absolute system and the gravimetric system. It is scientifically undesirable to combine two separate systems within a single standard. This test method has been written using SI units; however, inch-pound conversions are given in the gravimetric system, where the pound (lbf) represe...

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ASTM D6528-17 - Standard Test Method for Consolidated Undrained Direct Simple Shear Testing of Fine Grain Soils
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6528 − 17
Standard Test Method for
Consolidated Undrained Direct Simple Shear Testing of Fine
1
Grain Soils
This standard is issued under the fixed designation D6528; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope* system, where the pound (lbf) represents a unit of force
(weight). The use of balances or scales recording pounds of
1.1 This test method defines equipment specifications and
3
mass (lbm), or the recording of density in lb/ft should not be
testing procedures for the measurement of constant volume
regarded as nonconformance with this test method.
strength and stress-strain characteristics of cohesive soils after
one-dimensional consolidation using a constant rate of simple 1.6 All observed and calculated values shall conform to the
shear deformation mode of loading. The constant volume guidelines for significant digits and rounding established in
condition is equivalent to the undrained condition for saturated Practice D6026.
specimens. 1.6.1 Theproceduresusedtospecifyhowdataarecollected/
recorded or calculated in this test standard are regarded as the
1.2 This test method is written specifically for devices that
industry standard. In addition, they are representative of the
test rectangular parallelepiped or cylindrical specimens. Other
significant digits that should generally be retained. The proce-
more general devices, such as the torsional shear hollow
dures used do not consider material variation, purpose for
cylinder,maybeusedtoperformconsolidatedconstantvolume
obtaining the data, special purpose studies, or any consider-
simple shear tests but are beyond the scope of this test method.
ations for the user’s objectives; it is common practice to
1.3 This test method is applicable to testing intact, labora-
increase or reduce significant digits of reported data to be
tory reconstituted, and compacted soils, however, it does not
commensuratewiththeseconsiderations.Itisbeyondthescope
include specific guidance for reconstituting or compacting test
of this test standard to consider significant digits used in
specimens.
analysis methods for engineering design.
1.4 It shall be the responsibility of the agency requesting 1.6.2 Measurements made to more significant digits or
better sensitivity than specified in this standard shall not be
this test to specify the magnitude of the vertical consolidation
regarded a nonconformance with this standard.
stress prior to constant volume shear and, when appropriate,
the maximum vertical consolidation stress, which will result in
1.7 This standard does not purport to address all of the
an overconsolidated specimen.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
1.5 Units—The values stated in SI units are to be regarded
priate safety, health, and environmental practices and deter-
as the standard. No other units of measurement are included in
mine the applicability of regulatory limitations prior to use.
this standard. Reporting of test results in units other than SI
1.8 This international standard was developed in accor-
shall not be regarded as nonconformance with this test method.
dance with internationally recognized principles on standard-
1.5.1 In the engineering profession it is customary practice
ization established in the Decision on Principles for the
touse,interchangeably,unitsrepresentingbothmassandforce,
Development of International Standards, Guides and Recom-
unless dynamic calculations (F=Ma) are involved.This implic-
mendations issued by the World Trade Organization Technical
itly combines two separate systems of units, that is, the
Barriers to Trade (TBT) Committee.
absolute system and the gravimetric system. It is scientifically
undesirable to combine two separate systems within a single
2. Referenced Documents
standard. This test method has been written using SI units;
2
however, inch-pound conversions are given in the gravimetric 2.1 ASTM Standards:
D653 Terminology Relating to Soil, Rock, and Contained
Fluids
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.05 on Strength and
2
Compressibility of Soils. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Aug. 1, 2017. Published September 2017. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of
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