Why: The main reason that engineers conduct the Triaxial Compression Test is to obtain the shear
strength parameters of a soil specimen. These parameters include vital information concerning
the overall shear strength of the sample, such as the soil's cohesion and angle of internal friction.
This information can then be used to obtain an accurate analysis of the soil's shear strength.
Although there are several types of tests used to determine the shear strength of a soil sample,
the Triaxial Compression Test typically yields the most accurate results, as it is the only type of test configured to simulate the lateral pressure that is exerted on a soil in situ.
How:The Triaxial Compression Test is conducted by wrapping a cylindrical soil sample in a rubber membrane, and then placing the sample inside the triaxial chamber. Once inside the chamber, a
specific lateral pressure is applied to all sides of the soil specimen by water or compressed air.
In the Unconsolidated-Undrained (UU) variation of the Triaxial Compression Test, the soil
sample is not allowed to consolidate at this juncture of the experiment. With the soil sample
now properly in place, a vertical load is applied to the top of the specimen. This load is
gradually increased until the specimen fails, and both the vertical and lateral pressures at this
point are recorded. To end the experiment, the soil sample is removed from the triaxial chamber, and carefully discarded. The experiment is typically repeated several times, using either a
higher or lower lateral pressure during each testing. The results of these tests can then be
analyzed and compared to obtain important information about the soil's shear strength.
The triaxial test measures a soil's shear strength, and is similar to what other soil shear strength
The unconsolidated-undrained (UU) triaxial test is similar to the unconfined...