$1-$ For the active thrust on the smooth vertical wall shown in the figure and assuming that the entire backfill is in the active state $Ka=\frac{1-sin}{1+sin}$ :

A$-$ Draw the lateral earth pressure diagram showing all stresses.

B$-$ Calculate the total force acting on the wall. $($do not calculate its location$)$

$2-$ It is proposed to build a $10$ story building with a mat foundation of $15m20m,$ in a saturated clay where cu $=60k\frac{N}{m}2,=18\mathrm{.}5k\frac{N}{m}3.$ Assume approximately $16k\frac{N}{m}2$ per floor for the live and dead loads.

At what depth would you place the mat to make this a fully compensated foundation?