$4\mathrm{.}5$ Figure P$4\mathrm{.}5$ shows a wall in sand where the groundwater level $H_1=2\mathrm{.}0m$ and $H_2=4\mathrm{.}0m.$ The effective strength parameters are $c^{\text{'}}=0$ and ${}^{\text{'}}=34.$ The unit weight is $=16k\frac{N}{m^3},{}_{\text{s}\text{a}\text{t}}=20k\frac{N}{m^3}.$ Use Rankine's earth pressure theory to compute the total active force per unit length of the wall and the location of the resultant.

$4\mathrm{.}6$ Redo problem $4\mathrm{.}5$ with $H_1=3\mathrm{.}0m$ and $H_2=4\mathrm{.}0m.$ The effective strength parameters are $c^{\text{'}}=0$ and ${}^{\text{'}}=35.$ The unit weight is $=15k\frac{N}{m^3}*=22k\frac{N}{m^3}.$