Question

A footing is resting on a fully saturated clayey strata. For checking the initial stability, shear parameters are used from which one of the following?

• A. Consolidated non-drained test
• B. Unconsolidated drained test
• C. Unconsolidated non-drained test
• D. Unconsolidated non-drained test with pore pressure measurement

Answer 1

The correct option is D Unconsolidated non-drained test with pore pressure measurement

UU (unconsolidated undrained) test: In this, cell pressure is applied without allowing drainage. Then keeping cell pressure constant, deviator stress is increased to failure without drainage.
CU (consolidated undrained) test: In this, drainage is allowed during cell pressure application. Then without allowing further drainage, deviator stress is increased keeping cell pressure constant.
CD (consolidated drained) test: This is similar to CU test except that as deviator stress is increased, drainage is permitted. The rate of loading must be slow enough to ensure no excess pore water pressure develops.