Ground surface

G$.$W$.$T $$

NC clay

$C_c=0\mathrm{.}4,{}_{\text{s}\text{a}\text{t}\text{u}\text{r}\text{a}\text{t}\text{e}\text{d}}=120pcf$

$N=10$ blows$/$ft

Clay

Void ratio $(e_0)=0\mathrm{.}8$

RockA wall footing of $6$ ft width founded at $2-ft$ depth below ground surface, as shown in figure. The Ground Water Table $($GWT$)$ is located $2$ ft below the ground surface. The total unit weight of soil is $120$ pcf $.$

a$)$ Using the given uncorrected SPT$-$N$,$ determine the undrained shear strength $(S_u)$ of the clay soil. The hammer used with the SPT had $75\%$ efficieney. $($do correction for hammer efficiency only$)$

b$)$ Check bearing capacity safety of the footing to carry a factored load