$5-$ A $2m3m$ flexible foundation is constructed $1\mathrm{.}5m$ into saturated clay with rock located $6$

meters below the bottom of footing. The clay has an OCR of $2\mathrm{.}5,$ an applied bearing pressure of

$75k\frac{N}{m^2}$ and an $S_u=60k\frac{N}{m^2}\frac{,}{P}$I $=45.$ Determine the average elastic settlement. Use Figure $9\mathrm{.}1.$