Problem $3(4\mathrm{.}5$ pts$)$

Two triaxial compression tests are conducted on identical specimens of the same saturated clay.

In the first test the soil is first consolidated to sc $=350$ kPa and u $0=200$ kPa and then sheared under

drained conditions decreasing the chamber pressure while keeping the axial stress constant. At

failure s $3=260$ kPa.

In the second test, the specimen is consolidated to sc $=700$ kPa and u $0=500$ kPa, then it is sheared

under undrained conditions increasing the axial stress while keeping the chamber pressure constant.

At failure $($s $1-$s $3)=130$ and the excess pore pressure Du$=113$ kPa.

a$)$ Neatly summarize in a table the stresses at failure $($s $1,$ s $3,$ s$\text{'}1,$ s$\text{'}3,$ u$)$ for both tests.

b$)$ Draw the total and effective Mohr circles at failure for the two specimens and determine the

Mohr$-$Coulomb strength parameters $($c$$ and f$).$

c$)$ Do you believe this clay is normally or overconsolidated?