A $6-$m deep excavation is to be constructed in a medium to coarse sand with gravel $($SPT $($N$1)60$

$=30).$ A site investigation at the site shows the soil unit weight and effective frictional angle

of $20$ kN$/$m$3$

and $38,$ respectively. The wall facing has sufficient toe resistance.

a$)$ Determine the total load carried by the pressure$-$grouted anchors installed as shown in the

figure below. Assume the horizontal spacing between anchors is $2$ meters.

b$)$ Determine the sizes of the bar and trumpet opening $($a steel of grade $1035$ MPa is selected

and the soil is not aggressive$).$

c$)$ Determine the unbounded and bond lengths of the anchor.

Since pressure grouting is used, care must be taken for the minimum overburden depth and

critical failure surface requirements.