Correct Answer - Option 2 : consolidated drained test
Explanation:
Types of Triaxial test on the basis of Drainage:
1. Unconsolidated Undrained test (UU test):
(i) It is quick test and may complete in 5-10 minutes.
(ii) In this test water is not allowed to leave the soil either during the consolidation stage (confining stage) nor shear stage (deviator stage).
(iii) Such tests are suitable for low permeable soil such as clays with fast loading.
(iv) UU test is carried out for evaluation of short-term stability of the structure.
2. Consolidated Undrained Test (CU test):
(i) During the first stage of confining pressure, drainage is allowed from the soil sample. Hence consolidation will take place. But during vertical shear loading, drainage is not permitted.
(ii) Example: stability analysis of earthen dam during the sudden drawdown.
3. Consolidation Drain test (CD test):
(i) Drainage is permitted during the self-pressure (confining pressure) stage and shear stage both.
(ii) This test is the most time taking and for some soils may take several weeks. So, it is also called ‘slow test;
(iii) CD test is carried out for evaluation of long-term stability of the structure.
