Auestion $(3)(15$ Miark$)$

A sroup pile consisted of a number of $8$ individual piles as shown in Figure below. The pile diameter Piles are embedded in $2$ clay is $20m.$ Center$-$to$-$center spacing of piles is $0\mathrm{.}7m$ in both directions. Calculate the group factor of safety with ground water table far below the pile tip. It is required io