$4$b$.$ Use the shear strength parameters which you obtained from Question $4$a$.$ In addition, consider the

following: A and B parameters of this saturated sand are $0\mathrm{.}8$ and $0\mathrm{.}96$ respectively. A triaxial sample

of this soil is consolidated under a cell pressure of $300$kN$//$m$^(2)$ and back pressure $($pore water pressure$)$

of $100$kN$//$m$^(2).$ Once the consolidation was completed, the sample

was sheared under undrained

conditions by applying a vertical load.

What would be the principal stress difference and pore water pressure at failure?

Provide your working out below; add more pages if necessary

Solve Question $4$B please, Angle is calculated to be $27\mathrm{.}51$ degrees, Cohesion is $0.$ Thank you!