Question

In an unconfined compression test on a saturated clay, the undrained shear strength was found to be $6t/m^2$. If a sample of the same soil is tested in an undrained condition in triaxial compression at a cell pressure of $20t/m^2$, then the major principal stress at failure will be

• A. $48t/m^2$
• B. $32t/m^2$
• C. $24t/m^2$
• D. $12t/m^2$

Answer 1

The correct option is B $32t/m^2$

Major principal stress in undrained test
$=$ cell pressure $+$ undrained shear stength $\times 2$
$=20+6\times 2=32t/m^2$