Standard Test Method for Consolidated Undrained Cyclic Direct Simple Shear Test under Constant Volume with Load Control or Displacement Control

SIGNIFICANCE AND USE
5.1 Cyclic direct simple shear strength test results are used most often for evaluating the ability of a soil to resist shear stresses induced in a soil mass during earthquake loading, offshore storm loading, etc.  
5.2 In this test, the cyclic strength is measured under constant volume conditions that are equivalent to undrained conditions; hence, the test is applicable to field conditions in which the soils have consolidated under one set of stresses, and then are subjected to changes in stress/strain without time for further drainage to take place.  
5.3 The cyclic strength is a function of many factors including density, confining pressure, stress history, grain structure, specimen preparation procedure, frequency, and characteristics of the cyclic loading applied. Therefore, test factors shall be considered during evaluation of test results.  
5.4 The state of stress within the direct 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. Some effective stress parameters that could be derived from a cyclic direct simple shear test shall not be confused with corresponding parameters derived from other shear tests having better defined states of stress (that is, cyclic triaxial tests).  
5.5 The values of settlement in saturated soil after cyclic loading can be assessed from the test results by allowing volume change at the end of the shearing to achieve same vertical effective stresses as at end of primary consolidation.  
5.6 The data from the consolidation portion of this test are comparable to results obtained using Test Method D2435/D2435M provided that the more rigorous consolidation procedure of Test Method D2435/D2435M is followed.
SCOPE
1.1 This test method defines equipment specifications and testing procedures for the measurement of cyclic strength, number of cycles to liquefaction or cyclic properties (Modulus and Damping) of soils, after one-dimensional consolidation using a cyclic mode of loading.  
1.2 The cyclic shearing can be applied using load control or displacement control. It shall be the responsibility of the agency requesting this test to specify the magnitude and frequency of the cyclic loading. Other loading histories may be used if required by the agency requesting the testing.  
1.3 This test method is written specifically for devices that test cylindrical specimens enclosed in a wire-reinforced membrane or a soft membrane within a stack of rigid rings (this test method applies to Teflon coated rigid rings as well). Other types of shear devices are beyond the scope of this test method.  
1.4 This test method can be used for testing cohesionless free draining soils or fine grained soils. However, this test method may be followed when testing most soil types if care is taken to ensure that any special considerations required for such soils are accounted for.  
1.5 The shearing phase of this test is conducted under constant volume conditions. Since the lateral confinement system prevents radial specimen strains, the constant volume condition is accomplished by preventing specimen height change during shear. Shearing under constant volume can be performed on dry or saturated specimens. The constant volume condition is equivalent to the undrained condition for fully saturated specimens. Cyclic direct simple shear testing with truly undrained conditions (restricting pore water flow from and into the specimen) can be performed using some simple shear devices, but is beyond the scope of this standard.2  
1.6 The cyclic strength of a soil is determined based on the number of cycles required to reach a limiting double amplitude shear strain or a single amplitude shear strain, while liquefaction is more commonly defined as 100 % change in vertical stress ratio (ch...

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ASTM D8296-19 - Standard Test Method for Consolidated Undrained Cyclic Direct Simple Shear Test under Constant Volume with Load Control or Displacement Control
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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: D8296 − 19
Standard Test Method for
Consolidated Undrained Cyclic Direct Simple Shear Test
under Constant Volume with Load Control or Displacement
1
Control
This standard is issued under the fixed designation D8296; 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 and into the specimen) can be performed using some simple
2
shear devices, but is beyond the scope of this standard.
1.1 This test method defines equipment specifications and
1.6 The cyclic strength of a soil is determined based on the
testing procedures for the measurement of cyclic strength,
number of cycles required to reach a limiting double amplitude
number of cycles to liquefaction or cyclic properties (Modulus
shear strain or a single amplitude shear strain, while liquefac-
and Damping) of soils, after one-dimensional consolidation
tion is more commonly defined as 100 % change in vertical
using a cyclic mode of loading.
stress ratio (change in effective vertical stress during shearing
1.2 The cyclic shearing can be applied using load control or
divided by effective vertical stress at end of primary consoli-
displacement control. It shall be the responsibility of the
dation). The change in vertical stress ratio in constant volume
agency requesting this test to specify the magnitude and
shearing is equivalent to the excess pore pressure ratio (excess
frequency of the cyclic loading. Other loading histories may be
pore pressure during shearing divided by effective vertical
used if required by the agency requesting the testing.
stress at end of primary consolidation) under undrained con-
ditions.Thestraincriterionisonlyapplicablewhenperforming
1.3 This test method is written specifically for devices that
load controlled tests; 100 % change in vertical stress ratio can
test cylindrical specimens enclosed in a wire-reinforced mem-
be used for both, load and displacement control. For displace-
brane or a soft membrane within a stack of rigid rings (this test
ment control testing, the criterion to stop the test could be a
method applies to Teflon coated rigid rings as well). Other
specified number of cycles.
typesofsheardevicesarebeyondthescopeofthistestmethod.
1.7 This test method is applicable to testing intact,
1.4 This test method can be used for testing cohesionless
reconstituted, or compacted specimens; however, it does not
free draining soils or fine grained soils. However, this test
include specific guidance for preparing, reconstituting or com-
method may be followed when testing most soil types if care is
pacting test specimens.
taken to ensure that any special considerations required for
1.8 It shall be the responsibility of the agency requesting
such soils are accounted for.
this test to specify the magnitude of the consolidation stress
1.5 The shearing phase of this test is conducted under
priortoshearand,ifassigned,anunloadingconsolidationstage
constant volume conditions. Since the lateral confinement
may be required for over-consolidating the specimen.
system prevents radial specimen strains, the constant volume
1.9 All recorded and calculated values shall conform to the
condition is accomplished by preventing specimen height
guide for significant digits and rounding established in Practice
change during shear. Shearing under constant volume can be
D6026.
performed on dry or saturated specimens.The constant volume
1.9.1 Theproceduresusedtospecifyhowdataarecollected/
condition is equivalent to the undrained condition for fully
recorded and calculated in this test method are regarded as the
saturated specimens. Cyclic direct simple shear testing with
industry standard. In addition, they are representative of the
truly undrained conditions (restricting pore water flow from
significant digits that shall generally be retained. The proce-
dures used do not consider material variation, purpose for
obtaining the data, special purpose studies, or any consider-
ations for the user’s objectives; it is common practice to
increase or reduce significant digits of reported data to be
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.09 on Cyclic and
2
Dynamic Properties of Soils. Testsshearedundertrulyundrainedconditionsshouldbeperformedexclusively
Current edition approved Nov. 1, 2019. Published November 2019. DOI: on saturated specimens. Therefore, backpressure saturation is required to ensure
10.1520/D
...

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