ASTM D3080/D3080M-23
(Test Method)Standard Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions
Standard Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions
SIGNIFICANCE AND USE
5.1 The direct shear test is suited to the relatively rapid determination of the drained friction angle of soils under consolidated drained conditions because the drainage paths through the test specimen are short, allowing excess pore pressure to dissipate more rapidly than other drained strength tests. It is applicable for testing intact, or reconstituted specimens. There is, however, a limitation on the maximum particle size (see 6.2.1 and 6.2.2).
5.2 The testing protocols represent a field situation where complete consolidation has occurred under the existing normal stresses. Failure is reached slowly under drained conditions to allow excess pore pressure dissipation during shear. The shear rate must meet the requirements of 9.10. The results from several tests may be used to express the relationship between normal stress on the failure plane and drained shear strength.
Note 1: The equipment specified in this standard method is not appropriate for performing undrained shear tests. Using a fast displacement rate without proper control of the volume of the specimen will result in partial drainage and incorrect measurements of shear parameters.
5.3 During the direct shear test, there is rotation of principal stresses and failure may not occur on the weakest plane since failure is forced to occur on or near a plane through the middle of the specimen. The fixed location of the plane in the test can be an advantage in determining the shear resistance along recognizable weak planes within the soil material and for testing interfaces between dissimilar materials.
5.4 There are some limitations of the test, such as nonuniformity of shear stress on the failure plane and possibilities of nonuniformity of the failure plane due to nonuniformities within the soil and applied forces (moments caused by top half of shear box movement either up or down during shearing, and the like). Furthermore, when testing intact stiff clays, which are highly overconsolidated, there...
SCOPE
1.1 This test method covers the determination of the consolidated drained shear strength of one specimen of a soil material under direct shear boundary conditions. The specimen is deformed at a controlled rate on or near a single shear plane determined by the configuration of the apparatus.
1.2 Shear stresses and displacements are nonuniformly distributed within the specimen. An appropriate height of the failure zone cannot be defined for calculation of shear strains. Therefore, stress-strain relationships or any associated quantity such as the shear modulus, cannot be determined from this test.
1.3 The results of the test are affected by the presence of coarse-grained soil or rock particles, or both, which may make the testing data invalid in some cases. Check requirements of maximum soil particle size in 6.2.1 and 6.2.2.
1.4 Test conditions, including normal stress, access to water during consolidation and shearing, and specimens conditions should be selected to represent the field conditions being investigated and are left to the engineer or office requesting the test. The rate of shearing must be slow enough to ensure drained conditions.
1.5 Generally, three or more tests are performed on specimens from one soil sample, each under a different normal load, to determine the effects upon shear resistance and displacement. The development of criteria to interpret and evaluate test results is left to the engineer or office requesting the test. Interpretation of multiple tests requires engineering judgment and is beyond the scope of this test method. This test method pertains to the requirements for a single test.
1.6 This test method limits the maximum particle size of the test specimen based on the size of the shear box. Likewise, the gap size during shear is specified. It is acceptable for the testing requester to require a certain gap size between the upper and lower shear box halves to accommodate certa...
General Information
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Standards Content (Sample)
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: D3080/D3080M − 23
Standard Test Method for
Direct Shear Test of Soils Under Consolidated Drained
1
Conditions
This standard is issued under the fixed designation D3080/D3080M; 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* particles. Presently there is insufficient information available
for specifying the gap dimension based on particle size
1.1 This test method covers the determination of the con-
distribution.
solidated drained shear strength of one specimen of a soil
material under direct shear boundary conditions. The specimen
1.7 Units—The values stated in either inch-pound units or
is deformed at a controlled rate on or near a single shear plane
SI units [given in brackets] are to be regarded separately as
determined by the configuration of the apparatus.
standard. The values stated in each system may not be exact
equivalents; therefore, each system shall be used independently
1.2 Shear stresses and displacements are nonuniformly dis-
of the other. Combining values from the two systems may
tributed within the specimen. An appropriate height of the
result in nonconformance with the standard.
failure zone cannot be defined for calculation of shear strains.
Therefore, stress-strain relationships or any associated quantity
1.7.1 The gravitational system of inch-pound units is used
such as the shear modulus, cannot be determined from this test.
when dealing with inch-pound units. In this system, the pound
(lbf) represents a unit of force (weight), while the unit for mass
1.3 The results of the test are affected by the presence of
is a slug. The slug unit is not given, unless dynamic (F = ma)
coarse-grained soil or rock particles, or both, which may make
calculations are involved.
the testing data invalid in some cases. Check requirements of
1.7.2 It is common practice in the engineering/construction
maximum soil particle size in 6.2.1 and 6.2.2.
profession to concurrently use pounds to represent both a unit
1.4 Test conditions, including normal stress, access to water
of mass (lbm) and of force (lbf). This practice implicitly
during consolidation and shearing, and specimens conditions
combines two separate systems of units; the absolute and the
should be selected to represent the field conditions being
gravitational systems. It is scientifically undesirable to com-
investigated and are left to the engineer or office requesting the
bine the use of two separate sets of inch-pound units within a
test. The rate of shearing must be slow enough to ensure
single standard. As stated, this standard includes the gravita-
drained conditions.
tional system of inch-pound units and does not use/present the
1.5 Generally, three or more tests are performed on speci-
slug unit of mass. However, the use of balances and scales
mens from one soil sample, each under a different normal load, 3
recording pounds of mass (lbm) or recording density in lbm/ft
to determine the effects upon shear resistance and displace-
shall not be regarded as nonconformance with this standard.
ment. The development of criteria to interpret and evaluate test
1.8 All observed and calculated values shall conform to the
results is left to the engineer or office requesting the test.
guidelines for significant digits and rounding established in
Interpretation of multiple tests requires engineering judgment
Practice D6026, unless superseded by this test method.
and is beyond the scope of this test method. This test method
pertains to the requirements for a single test. 1.8.1 For purposes of comparing a measured or calculated
value(s) with specified limits, the measured or calculated
1.6 This test method limits the maximum particle size of the
value(s) shall be rounded to the nearest decimal of significant
test specimen based on the size of the shear box. Likewise, the
digits in the specified limit.
gap size during shear is specified. It is acceptable for the testing
1.8.2 The procedures used to specify how data are collected/
requester to require a certain gap size between the upper and
recorded and calculated in the standard are regarded as the
lower shear box halves to accommodate certain sand size
industry standard. In addition, they are representative of the
significant digits that generally should be retained. The proce-
1
dures used do not consider material variation, purpose for
This test method is under the jurisdiction of ASTM Committee D18 on Soil and
Rock and is the d
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