ASTM D5311-92(2004)
(Test Method)Standard Test Method for Load Controlled Cyclic Triaxial Strength of Soil
Standard Test Method for Load Controlled Cyclic Triaxial Strength of Soil
SIGNIFICANCE AND USE
Cyclic triaxial strength test results are used for evaluating the ability of a soil to resist the shear stresses induced in a soil mass due to earthquake or other cyclic loading.
5.1.1 Cyclic triaxial strength tests may be performed at different values of effective confining pressure on isotropically consolidated specimens to provide data required for estimating the cyclic stability of a soil.
5.1.2 Cyclic triaxial strength tests may be performed at a single effective confining pressure, usually equal to 14.5 lb/in. 2(100 kN/m2), or alternate pressures as appropriate on isotropically consolidated specimens to compare cyclic strength results for a particular soil type with that of other soils, Ref (2).
The cyclic triaxial test is a commonly used technique for determining cyclic soil strength.
Cyclic strength depends upon many factors, including density, confining pressure, applied cyclic shear stress, stress history, grain structure, age of soil deposit, specimen preparation procedure, and the frequency, uniformity, and shape of the cyclic wave form. Thus, close attention must be given to testing details and equipment.
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 ().
1.3 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 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...
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Designation: D 5311 – 92 (Reapproved 2004)
Standard Test Method for
Load Controlled Cyclic Triaxial Strength of Soil
This standard is issued under the fixed designation D5311; 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 (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
tothespecimeniscontrolledbythestressconditionsattheend
load-controlled cyclic triaxial technique.
ofconsolidationandthepore-waterpressuresgeneratedduring
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,theeffectiveconfiningpressureisreduced,contrib-
ditions during earthquake or other cyclic loading.
uting to the tendency of the specimen to neck during the
1.4 Cyclictriaxialstrengthtestsaredestructive.Failuremay
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.
shownthatdifferentmethodsofreconstitutingspecimenstothe
Whentestingwell-gradedmaterials,silts,orclays,itshouldbe
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
menendstonotingeneralrepresentpore-waterpressurevalues
stronger than reconstituted specimens.
throughout the specimen. However, this test method may be
1.6.5 Theinteractionbetweenthespecimen,membrane,and
followedwhentestingmostsoiltypesifcareistakentoensure
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-
triaxialteststosimulatethestressandstrainconditionsofasoil
tion in specimens of cohesionless soils. These changes can
element in the field during an earthquake.
significantly influence the test results.
1.6.1 Nonuniformstressconditionswithinthetestspecimen
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
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
ground liquefaction.
Rock and is the direct responsibility of Subcommittee D18.09 on Dynamic
Properties of Soils. 1.7 The values stated in both inch-pound and SI units are to
Current edition approved Oct. 15, 1992. Published January 1993.
be regarded separately as the standard. The values given in
The boldface numbers in parentheses refer to a list of references at the end of
parentheses are for information only.
the text.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5311 – 92 (2004)
1.8 This standard does not purport to address all of the 3.2.1 full or 100 % pore pressure ratio— a condition in
safety concerns, if any, associated with its use. It is the which Du equals s8 .
3c
responsibility of the user of this standard to establish appro- 3.2.2 peak pore pressure ratio—themaximumporepressure
priate safety and health practices and determine the applica- ratio measured during a particular loading sequence.
bility of regulatory limitations prior to use. 3.2.3 peak (single amplitude) strain—the maximum axial
strain (from the origin or initial step) in either compression or
2. Referenced Documents
extension produced during a particular loading sequence.
3.2.4 peak to peak (double amplitude) strain— the differ-
2.1 ASTM Standards:
ence between the maximum axial strain in compression and
D422 Test Method for Particle-Size Analysis of Soils
extensionduringagivencycleundercyclicloadingconditions.
D653 Terminology Relating to Soil, Rock, and Contained
3.2.5 pore pressure ratio—the ratio, expressed as a percent-
Fluids
age, of the change of excess pore-water pressure, D u,tothe
D854 Test Method for Specific Gravity of Soils
effective minor principal stress, s8 , at the end of primary
D1587 Practice for Thin-Walled Tube Sampling of Soils
3c
D2216 TestMethodforLaboratoryDeterminationofWater consolidation.
(Moisture) Content of Soil and Rock
4. Summary of Test Method
D2850 Test Method for Unconsolidated, Undrained Com-
4.1 A cylindrical soil specimen is sealed in a watertight
pressive Strength of Cohesive Soils in Triaxial Compres-
rubber membrane and confined in a triaxial chamber where it
sion
is subjected to a confining pressure.An axial load is applied to
D 4220 Practice for Preserving and Transporting Soil
the top of the specimen by a load rod.
Samples
4.2 Specimens are consolidated isotropically (equal axial
D4253 TestMethodsforMaximumIndexDensityandUnit
and radial stress). Tubing connections to the top and bottom
Weight of Soils Using a Vibratory Table
specimen platens permit flow of water during saturation,
D4254 Test Method for Minimum Index Density and Unit
consolidation and measurement of pore-water pressure during
Weight of Soils and Calculation of Relative Density
cyclic loading.
D4318 Test Method for Liquid Limit, Plastic Limit, and
4.3 Following saturation and consolidation, the specimen is
Plasticity Index of Soils
subjected to a sinusoidally varying axial load by means of the
D4767 Test Method for Consolidated-Undrained Triaxial
loadrodconnectedtothespecimentopplaten.Thecyclicload,
Compression Test on Cohesive Soils
specimen axial deformation, and porewater pressure develop-
3. Terminology ment with time are monitored.
4.4 The test is conducted under undrained conditions to
3.1 Definitions:
approximate essentially undrained field conditions during
3.1.1 Definitions for terms used in this test method (includ-
earthquake or other dynamic loading. The cyclic loading
ing liquefaction) are in accordance with Terminology D653.
generally causes an increase in the pore-water pressure in the
Additional descriptions of terms are defined in 3.2 and in 10.2
specimen, resulting in a decrease in the effective stress and an
and Fig. 1.
increase in the cyclic axial deformation of the specimen.
3.2 Definitions of Terms Specific to This Standard:
4.5 Failure may be defined as when the peak excess pore-
water pressure equals the initial effective confining pressure,
full or 100% pore pressure ratio (sometimes called initial
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
liquefaction), or in terms of a limiting cyclic strain or perma-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
nent strain.
Standardsvolume information, refer to the standard’s Document Summary page on
the ASTM website.
5. Significance and Use
5.1 Cyclic triaxial strength test results are used for evaluat-
ing the ability of a soil to resist the shear stresses induced in a
soil mass due to earthquake or other cyclic loading.
5.1.1 Cyclic triaxial strength tests may be performed at
different values of effective confining pressure on isotropically
consolidated specimens to provide data required for estimating
the cyclic stability of a soil.
5.1.2 Cyclic triaxial strength tests may be performed at a
single effective confining pressure, usually equal to 14.5 lb/in.
2(100 kN/m ), or alternate pressures as appropriate on isotro-
pically consolidated specimens to compare cyclic strength
resultsforaparticularsoiltypewiththatofothersoils,Ref (2).
5.2 Thecyclictriaxialtestisacommonlyusedtechniquefor
determining cyclic soil strength.
5.3 Cyclic strength depends upon many factors, including
FIG. 1 Schematic Representation of Load-Controlled Cyclic
Triaxial Strength Test Equipment density, confining pressure, applied cyclic shear stress, stress
D 5311 – 92 (2004)
history, grain structure, age of soil deposit, specimen prepara-
tionprocedure,andthefrequency,uniformity,andshapeofthe
cyclic wave form. Thus, close attention must be given to
testing details and equipment.
6. Apparatus
6.1 In many ways, triaxial equipment suitable for cyclic
triaxial strength tests is similar to equipment used for the
unconsolidated-undrained triaxial compression test (see Test
Method D2850) and the consolidated-undrained triaxial com-
pression test (see Test Method D4767). However, there are
special features described in the following subsections that are
requiredtoperformacceptablecyclictriaxialtests.Aschematic
representation of a typical load-controlled cyclic triaxial
strength test set-up is shown in Fig. 1.
6.2 Triaxial Compression Cell—Theprimaryconsiderations
in selecting the cell are tolerances for the piston, top cap, and
low friction piston seal.
6.2.1 Twolinearballbushingsorsimilarbearingsshouldbe
used to guide the load rod to minimize friction and to maintain
alignment.
6.2.2 The load rod diameter should be large enough to
minimize lateral bending.Aminimum load rod diameter of ⁄6
the specimen diameter has been used successfully in many
laboratories.
6.2.3 The load rod seal is a critical element in triaxial cell
design for cyclic soils testing. The seal must exert negligible
friction on the load rod. The maximum acceptable piston
friction tolerable without applying load corrections is com-
monly considered to be 6 2% of the maximum single
amplitude cyclic load applied in the test. The use of an air
bushing as proposed in Ref (3) will meet or exceed these
requirements.
6.2.4 Top and bottom platen alignment is critical if prema-
ture specimen failure caused by the application of a nonuni-
form state of stress to the specimen is to be avoided. Internal
tie-rod triaxial cells that allow for adjustment of alignment
beforeplacementofthechamberhavebeenfoundtoworkwell
at a number of laboratories.These cells allow the placement of
NOTE 1—(a) Eccentricity and (b) parallelism.
the cell wall after the specimen is in place between the loading
FIG. 2 Limits on Acceptable Platen and Load Rod Alignment
platens.Acceptablelimitsofplateneccentricityandparellelism
are shown in Fig. 2.
6.2.5 Since in cyclic triaxial tests extension as well as
able to maintain uniform cyclic loadings to at least 20%
compression loads may be exerted on the specimen, the load
peak-to-peak strains. Unsymmetrical compression-extension
rod shall be connected to the top platen by straight threads
load peaks, nonuniformity of pulse duration,“ ringing,” or load
backed by a shoulder on the piston that tightens up against the
fall-off at large strains shall not exceed tolerance illustrated in
platen.
Fig.3.Theequipmentshallalsobeabletoapplythecyclicload
6.2.6 Thereshallbeprovisionforspecimendrainageatboth
about an initial static load on the loading rod. Evaluate
the top and bottom platens.
uniformity of the load trace into the failure state to ensure that
6.2.7 Porous Discs—The specimen shall be separated from
load uniformity criteria presented in previous sections are
the specimen cap and base by rigid porous discs of a diameter
achieved. Show this in an appropriate way by calculating the
equaltothatofthespecimen.Thecoefficientofpermeabilityof
percentloaddrift(P )betweenthemaximumload(DP )
error max
the discs shall be approximately equal to that of fine sand
based on the initial loading cycle and the measured load in the
−5
−4
(3.9 310 in./s [1 310 cm/s]).The discs shall be regularly
nth cycle as follows:
checked to determine whether they have become clogged.
D P 5 DP 1D P (1)
~ !
max c e max
6.3 Dynamic loading equipment used for load-controlled
@~DP 1DP ! 2 ~DP1DP ! # 3100
c e max e n
cyclic triaxial tests shall be capable of applying a uniform
P 5
error
~DP 1DP !
c e max
sinusoidal load at a frequency range of 0.1 to 2.0 Hz. The
frequency of 1.0 Hz is preferred. The loading device shall be P should be < 5% at axial strains of 65%.
error
D 5311 – 92 (2004)
the test specimen to ensure that the necessary measurement
accuracy is achieved. The minimum performance characteris-
tics of the load cell are presented in Table 1.
6.4.2 Axial Deformation Measurement— Displacement
measuring devices such as linear variable differential trans-
former (LVDT), potentiometer-type deformation transducers,
andeddycurrentsensorsmaybeusediftheyhaveanaccuracy
of 6 0.02% of the initial specimen height (see Table 1).
Accurate deformation measurements require that the trans-
ducer be properly mounted to avoid excessive mechanical
system compression between the load frame, the triaxial cell,
the load cell, and the loading piston.
6.4.3 Pore-Water Pressure Transducer— The specimen
pore-water pressure shall be measured to within 6 0.25 psi (2
kPa). Duri
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