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Description / Abstract:
This test method covers the determination of the cyclic strength
(sometimes called the liquefaction potential) of saturated soils in
either intact or reconstituted states by the load-controlled cyclic
triaxial technique.
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).2
Cyclic triaxial strength tests are conducted under undrained
conditions to simulate essentially undrained field conditions
during earthquake or other cyclic loading.
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.
This test method is generally applicable for testing
cohesionless free draining soils of relatively high permeability.
When testing well-graded materials, silts, or clays, pore-water
pressures monitored at the specimen ends may not 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.
The values stated in either SI units or inch-pound units
[presented in brackets] are to be regarded separately as standard.
The values stated in each system may not be exact equivalents;
therefore, each system shall be used independently of the other.
Combining values from the two systems may result in non-conformance
with the standard. Reporting of test results in units other than SI
shall not be regarded as nonconformance with this test method.
All observed and calculated values shall conform to the guide
for significant digits and rounding established in Practice D6026.
The procedures in Practice D6026 that are used to specify how data
are collected, recorded, and calculated are regarded as the
industry standard. In addition, they are representative of the
significant digits that should generally be retained. The
procedures do not consider material variation, purpose for
obtaining the data, special purpose studies, or any considerations
for the objectives of the user. Increasing or reducing the
significant digits of reported data to be commensurate with these
considerations is common practice. Consideration of the significant
digits to be used in analysis methods for engineering design is
beyond the scope of this standard.
The method used to specify how data are collected, calculated,
or recorded in this standard is not directly related to the
accuracy to which the data can be applied in design or other uses,
or both. How one applies the results obtained using this standard
is beyond its scope.
This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory
limitations prior to use.
2 The boldface numbers in parentheses refer to a list
of references at the end of the text.
*A Summary of Changes section appears at the end of this
standard.