Queation $1$

$($a$)($i$)$ A designer suggents to use open$-$ended drinen pupo piles $($see the figure bolow$)$ for a

purticular deep foumdation to gonnate a higher beaning caprecty. Briefly dideribe if this type of

piles can emerate a highe bexing capscity coemped to conventional solid closed$-$ended piles

and how.

$($ii$)$ Pilo group efficiency factor can be greates fing for pillen driven into medium donse and.

Briefly describe how this can be porsible.

$($b$)$ For the soil profile given below, calcubate the rexuined depth of a single $300$ mm square

concrete pile driven into the : oil to carry a $100$ i Vi asfe joud with a factor of affoty of $3.$ It may

be assumed that the bearing capacity fictor $N_5=9$ and that the athasion factor $$ equalls $0\mathrm{.}85$

for the sott clay:

$[$NB: $q_B=N_C{C}_{ut}$ and that $[$:$c_a=*C_E$