A rectangular footing of size ${10}^{\text{'}}$ by ${20}^{\text{'}}$ feet is founded at a depth of six $(6^{\text{'}})$ feet below the

ground surface in a cohesive soil which may be assumed to fail in a general shear failure

condition. The colesive soil has a $c=945$ psf$.$ The specific gravity of the solid particles, $G_s$

equals $2\mathrm{.}7$ and the soil voids ratio is $0\mathrm{.}85.$ If the ground water table is located at the ground

surface and the cohesive soil is followed by a sandy soil at a depth of $100$ feet below the

foundation level and has a $$ value of $30.$ Determine the allowable safe load at the ground

surface that the foundation can carry.