Explain the Triaxial compression test representations.

The triaxial compression test is used to measure the shear strength of the soil.

The apparatus used in triaxial compression test are,

1. Axial Loading Piston

2. Cell pressure gauge

3. Dial gauge measuring vertical displacement.

4. Specimen Membrane.

5. Pore pressure gauge

6. Pore fluid drainage valve.

The procedure for the triaxial test is as follows:

• A saturated porous stone is placed on the pedestal and the cylindrical soil specimen is placed on it.
• The specimen is encased in a rubber membrane and sealed to the pedestal at the bottom as well as to the loading cap at the top by rubber O-ring the membrane is used to prevent the water from penetrating in to the soil sample.
• The triaxial cell is filled with water and pressure is applied to the water, which in turn is transmitted to the soil specimen all-round and at top. This pressure is called Cell Pressure.
• Now with the cell pressure held constant, additional axial stress is applied through the ram gradually until the sample fails. This additional axial stress is called Deviator stress.

There are three types of triaxial test.

1. UU: Unconsolidated-Undrained

2. CD: Consolidated-Drained.

3. CU: Consolidated-Undrained