A rectangular foundation $105m$ is to be designed, using a factor of safety of $3$ to carry a uniform load of $86\mathrm{.}6MN,$ in fully drained conditions in the following soil: $c^{\text{'}}=0,$ and ${}^{\text{'}}=35,=20k\frac{N}{m^3},{}_{\text{s}\text{a}\text{t}}=22k\frac{N}{m^3}$

a$)$ Determine a suitable founding depth

b$)$ Determine the percentage reduction in load carrying capacity that results from the ground water level rising

i$.$ To the underside of the footing

ii$.$ To the ground surface

c$)$ Calculate the factor of safety when the $86\mathrm{.}6MN$ load is applied and the two conditions in $($b$)$ occur

CEB $3319$ FOUNDATION ENGINERING

$48$