ASTM D5311-92(1996)
(Test Method)Standard Test Method for Load Controlled Cyclic Triaxial Strength of Soil
Standard Test Method for Load Controlled Cyclic Triaxial Strength of Soil
SCOPE
1.1 This test method covers the determination of the cyclic strength (sometimes called the liquefaction potential) of saturated soils in either undisturbed or reconstituted states by the load-controlled cyclic triaxial technique.
1.2 The cyclic strength of a soil is evaluated relative to a number of factors, including: the development of axial strain, magnitude of applied cyclic stress, number of cycles of stress application, development of excess pore-water pressure, and state of effective stress. A comprehensive review of factors affecting cyclic triaxial test results is contained in the literature (1).
1.3 Cyclic triaxial strength tests are conducted under undrained conditions to simulate essentially undrained field conditions during earthquake or other cyclic loading.
1.4 Cyclic triaxial strength tests are destructive. Failure may be defined on the basis of the number of stress cycles required to reach a limiting strain or 100% pore pressure ratio. See Section 3 for Terminology.
1.5 This test method is generally applicable for testing cohesionless free draining soils of relatively high permeability. When testing well-graded materials, silts, or clays, it should be recognized that pore-water pressures monitored at the specimen ends to not in general represent pore-water pressure values throughout the specimen. However, this test method may be followed when testing most soil types if care is taken to ensure that problem soils receive special consideration when tested and when test results are evaluated.
1.6 There are certain limitations inherent in using cyclic triaxial tests to simulate the stress and strain conditions of a soil element in the field during an earthquake.
1.6.1 Nonuniform stress conditions within the test specimen are imposed by the specimen end platens. This can cause a redistribution of void ratio within the specimen during the test.
1.6.2 A 90° change in the direction of the major principal stress occurs during the two halves of the loading cycle on isotropically consolidated specimens.
1.6.3 The maximum cyclic shear stress that can be applied to the specimen is controlled by the stress conditions at the end of consolidation and the pore-water pressures generated during testing. For an isotropically consolidated contractive (volume decreasing) specimen tested in cyclic compression, the maximum cyclic shear stress that can be applied to the specimen is equal to one-half of the initial total axial pressure. Since cohesionless soils are not capable of taking tension, cyclic shear stresses greater than this value tend to lift the top platen from the soil specimen. Also, as the pore-water pressure increases during tests performed on isotropically consolidated specimens, the effective confining pressure is reduced, contributing to the tendency of the specimen to neck during the extension portion of the load cycle, invalidating test results beyond that point.
1.6.4 While it is advised that the best possible undisturbed specimens be obtained for cyclic strength testing, it is sometimes necessary to reconstitute soil specimens. It has been shown that different methods of reconstituting specimens to the same density may result in significantly different cyclic strengths. Also, undisturbed specimens will almost always be stronger than reconstituted specimens.
1.6.5 The interaction between the specimen, membrane, and confining fluid has an influence on cyclic behavior. Membrane compliance effects cannot be readily accounted for in the test procedure or in interpretation of test results. Changes in pore-water pressure can cause changes in membrane penetration in specimens of cohesionless soils. These changes can significantly influence the test results.
1.6.6 The mean total confining pressure is asymmetric during the compression and extension stress application when the chamber pressure is constant. This is totally different from the symmetric stress in the simple shear case...
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Designation: D 5311 – 92 (Reapproved 1996)
Standard Test Method for
1
Load Controlled Cyclic Triaxial Strength of Soil
This standard is issued under the fixed designation D 5311; 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 1.6.2 A 90° change in the direction of the major principal
stress occurs during the two halves of the loading cycle on
1.1 This test method covers the determination of the cyclic
isotropically consolidated specimens.
strength (sometimes called the liquefaction potential) of satu-
1.6.3 The maximum cyclic shear stress that can be applied
rated soils in either undisturbed or reconstituted states by the
to the specimen is controlled by the stress conditions at the end
load-controlled cyclic triaxial technique.
of consolidation and the pore-water pressures generated during
1.2 The cyclic strength of a soil is evaluated relative to a
testing. For an isotropically consolidated contractive (volume
number of factors, including: the development of axial strain,
decreasing) specimen tested in cyclic compression, the maxi-
magnitude of applied cyclic stress, number of cycles of stress
mum cyclic shear stress that can be applied to the specimen is
application, development of excess pore-water pressure, and
equal to one-half of the initial total axial pressure. Since
state of effective stress. A comprehensive review of factors
cohesionless soils are not capable of taking tension, cyclic
affecting cyclic triaxial test results is contained in the literature
2 shear stresses greater than this value tend to lift the top platen
(1).
from the soil specimen. Also, as the pore-water pressure
1.3 Cyclic triaxial strength tests are conducted under und-
increases during tests performed on isotropically consolidated
rained conditions to simulate essentially undrained field con-
specimens, the effective confining pressure is reduced, contrib-
ditions during earthquake or other cyclic loading.
uting to the tendency of the specimen to neck during the
1.4 Cyclic triaxial strength tests are destructive. Failure may
extension portion of the load cycle, invalidating test results
be defined on the basis of the number of stress cycles required
beyond that point.
to reach a limiting strain or 100 % pore pressure ratio. See
1.6.4 While it is advised that the best possible undisturbed
Section 3 for Terminology.
specimens be obtained for cyclic strength testing, it is some-
1.5 This test method is generally applicable for testing
times necessary to reconstitute soil specimens. It has been
cohesionless free draining soils of relatively high permeability.
shown that different methods of reconstituting specimens to the
When testing well-graded materials, silts, or clays, it should be
same density may result in significantly different cyclic
recognized that pore-water pressures monitored at the speci-
strengths. Also, undisturbed specimens will almost always be
men ends to not in general represent pore-water pressure values
stronger than reconstituted specimens.
throughout the specimen. However, this test method may be
1.6.5 The interaction between the specimen, membrane, and
followed when testing most soil types if care is taken to ensure
confining fluid has an influence on cyclic behavior. Membrane
that problem soils receive special consideration when tested
compliance effects cannot be readily accounted for in the test
and when test results are evaluated.
procedure or in interpretation of test results. Changes in
1.6 There are certain limitations inherent in using cyclic
pore-water pressure can cause changes in membrane penetra-
triaxial tests to simulate the stress and strain conditions of a soil
tion in specimens of cohesionless soils. These changes can
element in the field during an earthquake.
significantly influence the test results.
1.6.1 Nonuniform stress conditions within the test specimen
1.6.6 The mean total confining pressure is asymmetric
are imposed by the specimen end platens. This can cause a
during the compression and extension stress application when
redistribution of void ratio within the specimen during the test.
the chamber pressure is constant. This is totally different from
the symmetric stress in the simple shear case of the level
1
This test method is under the jurisdiction of ASTM Committee D-18 on Soil ground liquefaction.
and Rock and is the direct responsibility of Subcommittee D18.09 on Dynamic
1.7 The values stated in both inch-pound and SI units are to
Properties of Soils.
be regarded separately as the standard. The values given in
Current edition approved Oct. 15, 1992. Published Janu
...
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