Question

The net ultimate bearing capacity of a purely cohesive soil

• A. depends on the width of the footing and is independent of the depth of the footing
• B. depends on the width as well as the depth of the footing
• C. depends on the depth, but is independent of the width, of the footing
• D. is independent of both the width and the depth of the footing

Answer 1

The correct option is D is independent of both the width and the depth of the footing

(d) As per Terzaghi's bearing capacity equation,
$q_{ult}=c{N}_c+\gamma D_f{N}_q+0.5\gamma B{N}_{\gamma }$

For a purely cohensive soil $N_q=1and{N}_{\gamma }=0$

$\therefore q_{ult}=c{N}_c+\gamma D_f$

$But{q}_{net.ult}=q_{ult}-\gamma D_f$

$\Rightarrow q_{net.ult}=c{N}_c+\gamma D_f-\gamma D_f$

$\Rightarrow q_{net,ult}=c{N}_c$