A sample of clay $($Sample A$)$ is isotropically normally consolidated to cell pressure of $400$ kPa and

$v0=2\mathrm{.}052($i$.$e$.v0$ is specific volume$).$ A second sample $($Sample B$)$ is istropically consolidated to

$863$ kPa and allowed to swell to a mean effective stress of $40$ kPa when $v0=2\mathrm{.}052.$ Both samples

were then subjected to standard undrained compression tests. The value of the soil constants for

clay are:

$M=0\mathrm{.}95,=3\mathrm{.}15$ and $=0\mathrm{.}19$

Find pore pressure at failure of each sample.