Example $10\mathrm{.}10$: A ring foundation is of $3\mathrm{.}60$ m external diameter and $2\mathrm{.}40$ m internal diam$-$

eter. It transmits a uniform pressure of $135k\frac{N}{m^2}.$ Calculate the vertical stress at a depth of

$1\mathrm{.}80$ m directly beneath the centre of the loaded area.