Page 19 - Grp3-Soil magazine (Final-Vid ver)

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(C) TRIAXIAL COMPRESSION TEST
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(C) TRIAXIAL COMPRESSION TEST
(i) Unconsolidated Undrained (UU)
(ii) Consolidated Undrained (CU)
(iii) Consolidated Drained (CD)
UU triaxial tests are termed total stress tests and
CU/CD triaxial tests are termed effective stress tests.
CU and CD Triaxial tests has 3 stages. It normally starts
with a saturation stage, which then leads onto a
consolidation stage.
The consolidated stage can be either:
a) isotropic; the stress surrounding the sample is
Figure 4: Triaxial System equal in all directions
b) anisotropic; the stress surrounding the sample is
not equal in all directions.
Last stage is shearing stage where it will be sheared
to failure.

*UU triaxial tests commonly do not have a saturation
or consolidation stage performed; the test normally
only consists of a shear stage.

UU triaxial tests is are quick tests while CD triaxial
tests are slow tests as during the shear stage of the
Figure 5: Stresses in an effective stress test
test, pore pressure is not allowed to build up, resulting
in very low strain rates. CU triaxial tests compromise
both slow and quick test.

Figure 4 shows the stresses involved with a total stress
test. Figure 5 summaries the stresses in an effective
stress test.

Triaxial Test Procedure

Watch this video for more detailed
explanation on tests & graph analysis!

PAGE 19