A sample of clay $($Sample A$)$ is isotropically normally consolidated to cell pressure of $400$kPa and $0=2\mathrm{.}052($i$.$e$.0$ 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 $0=2\mathrm{.}052.$ 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.