$($b$)$ A clay $/$ silt sample is taken from a depth of about $8$ m at the same site, as

shown on Figure $1,$ and subjected to a UU test. The cell pressure $(3)$ applied

was $50$ kPa and an additional stress $($i$.$e$.$ the deviator stress applied through

the loading ram$)$ of $80$ kPa was required to fail the sample. Determine the

undrained shear strength $($cu$)$;

$(15\%)$

$($c$)$ Use the Mohr circle construction to show the orientation of the failure plane for

the test described in Part $($b$)$;

$(15\%)$

$($d$)$ Another section of the same sample, as described in Part b$,$ is subjected to a

CU test. The cell pressure applied was equal to the in situ vertical effective

stress $($v$0).$ The deviator stress and pore water pressure measured at failure

were $101\mathrm{.}5$ kPa and $20$ kPa respectively. Determine cu$.$ Why is the value not

the same as in the UU test?

$(30\%)$

$($e$)$ For the test described in Part d$,$ assuming the effective cohesion $($c$)$ is equal

to $5$ kPa, determine the effective friction angle $()$;