Problem $8$

Consolidated undrained tests were performed on two samples of a clay soil. Each sample was isotropically consolidated before the axial stress was increased. The following are the obtained results. Sample $1$ results are at the peak deviatoric stress, while Sample $2$ results are at critical state.

a$.$ Draw Mohr circles $($total and effective stress$)$ for each test on the same graph $($use a compass and graph$/$engineering paper$).$ Use dashed lines to indicate the total stress and solid lines to indicate effective stress.

b$.$ Why are the total stress circles not the same size?

c$.$ Determine the friction angle for each test. Label on your plot. Scan the final plot and include with your main pdf file.

d$.$ Determine the undrained shear strength at the cell pressure $($confining pressure$)$ of $690$ kPa $.$