Problem $4(25$ Points$)$

A square cast$-$in$-$place concrete pile sxs $m$ is required to support a load of $NkN$ with a factor of safety of $2.$ The foundation area is $4m5m.$ The soil stratification consist of $3m$ of medium clay $(su=$A kPA;$Qcs=25,$OCR$=2,sat=18k\frac{N}{m}3)$ underlain by a deep deposit of overconsolidated clay $($su $($:$=$BkPA;$Qcs=24,$OCR$=4,sat=18\mathrm{.}50k\frac{N}{m}3$

s$-$m$=0\mathrm{.}4$ N$-$kN $=200$ A$-$kPa$=40$ B$-$kPa$=70$