Question No$.3$

$[15$ marks$]$

The above $18$ inch diameter concrete pile is to be driven at the site as shown above.

The piles modulus of elasticity is $57(4000{)}^{\frac{1}{2}}ki\frac{p}{i}{n}^2$

Pile Length is $55$ ft

The hammer is a Vulcan $140$ C $,$ with Pile hammer Ram of $14000$ lbs and Energy rating of $36000ft-lb$

Hammer efficiency is $0\mathrm{.}85$

Find the terminal driving blows per $ft(S)$

Given that

Qult $=\frac{eh(Eh)}{S+\frac{1}{2}So}$

So $=[\frac{2\text{e}\text{h}\text{E}\text{h}\text{L}}{AE}{]}^{\frac{1}{2}}$

Where;

eh $=$ efficiency of pile hammer

Eh $=$ Hammer Energy rating

$S=$ Average penetration of the pile from the last few drives

$So=$ elastic compression of pile

$L=$ length of pile

A $=$ cross sectional area of pile

$E=$ modulus of elasticity of pile material