$2-$ A $650-kN$ column load is supported on a $1\mathrm{.}5$ m wide by $2\mathrm{.}0$ m long by $0\mathrm{.}5$ m deep spread footing. The soil below is a well$-$graded normally consolidated sand with a unit weight of $18\mathrm{.}0k\frac{N}{m^3}$ and the following SPT values:

$\backslash$table$[[z(m),N_{60}$