ASTM D8295-19

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: D8295 − 19
Standard Test Method for
Determination of Shear Wave Velocity and Initial Shear
1
Modulus in Soil Specimens using Bender Elements
This standard is issued under the fixed designation D8295; 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 proposed and used. This test method only describes two of
these, Start to Start and Peak to Peak using a single sine wave
1.1 This test method covers the laboratory use of piezo-
signal sent to the transmitter bender element. Other interpre-
ceramic bender elements to determine the shear wave velocity
tation methods producing similar results may also be used.
in soil specimens. A shear wave is generated at one boundary
of a soil specimen and then received at an opposite boundary. 1.6 Bender element measurements may not work very well
The shear wave travel time is measured, which over a known
in some situations, like in extremely stiff soils where the
travel distance yields the shear wave velocity. From this shear generated shear wave amplitude may be exceedingly small.
wave velocity and the density of the soil specimen the initial
1.7 This test method does not cover the determination of
shear modulus (G ) can be determined, which is the result of
max
compressional wave velocity in soil specimens. This measure-
primary interest from bender element tests.
ment requires a different type of piezo-ceramic element
1.2 This shear wave velocity determination involves very
configuration, and such determinations are generally not useful
smallstrainsandisnon-destructivetoatestspecimen.Assuch,
in saturated soft soil specimens as the earliest identifiable
bender element shear wave velocity determinations can be compressional wave arrival at the receiver end of a saturated
made at any time and any number of times during a laboratory
specimen will likely have been transmitted through the (rela-
test. tively incompressible) specimen pore water rather than the
(compressible) soil skeleton.
1.3 This test method describes the use of bender elements in
a triaxial type test (for example, Test Methods D3999, D4767,
1.8 Units—The values stated in SI units are to be regarded
D5311,or D7181), but a similar procedure may be used for
as standard. No other units of measurement are included in this
other laboratory applications, like in Direct Simple Shear (Test
standard.
Method D6528) or oedometer tests (for example,Test Methods
1.9 All observed and calculated values shall conform to the
D2435 and D4186). Shear wave velocity can also be deter-
guidelines for significant digits and rounding established in
mined in unconfined soil specimens held together by matrix
Practice D6026, unless superseded by this test method.
suction.
1.9.1 Theproceduresusedtospecifyhowdataarecollected/
1.4 Shear wave velocity can be determined in different
recorded and calculated in the standard are regarded as the
directions in a triaxial test, for example vertically and horizon-
industry standard. In addition, they are representative of the
tally. Shear waves generated to determine shear wave velocity
significant digits that generally should be retained. The proce-
can also be polarized in different directions, for example a
dures used do not consider material variation, purpose for
horizontally propagating shear wave with either vertical or
obtaining the data, special purpose studies, or any consider-
horizontal polarization. This test method describes the use of
ations for the user’s objectives; and it is common practice to
bender elements mounted in the top platen and base pedestal of
increase or reduce significant digits of reported data to be
a triaxial test specimen to measure shear wave velocity in the
commensuratewiththeseconsiderations.Itisbeyondthescope
vertical direction.With additional bender elements mounted on
of these test methods to consider significant digits used in
opposite sides of a triaxial specimen, a similar procedure may
analysis methods for engineering data.
be used to determine horizontal shear wave velocity.
1.10 This standard does not purport to address all of the
1.5 Avariety of different interpretation methods to evaluate
safety concerns, if any, associated with its use. It is the
the shear wave travel time in a soil specimen have been
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1
ThistestmethodisunderthejurisdictionofASTMComm
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