Problem #$3$

A consolidated$-$undrained triaxial test was conducted on a saturated, normally consolidated clay.

The test results are:

${}_3=13l\frac{b}{i}{n}^2$

${}_1=32l\frac{b}{i}{n}^2$

Pore pressure at failure $(u)=5\mathrm{.}5l\frac{b}{i}{n}^2$

Determine $c,\frac{O}{,}{c}^{\text{'}},$ and $\frac{O}{{?}^{\text{'}}}.$