Which one of the following is the appropriate triaxial test to assess the immediate stability of an unloading problem, such as an excavation of a clay slope ?

ANS:B - CU test

The answer is correct.

When the stability of clay soil slope is required then we go for Undrained test for sure as clay can not be taken for the drained test due to prolonged results.

Now, when normally stability is checked for an unconsolidated test, we check against the creep of soil as we assume there won't be any immediate issue as the soil is cohesive.

However, for immediate stability, we have to push soil for critical loading that is Deviator load also consolidation loading!

So it will be Consolidated Undrained Test.