Question

A precast concrete pile is driven with a $50\text{kN}$ hammer falling through a height of $1.0\text{m}$ with an efficiency of 0.6. The set value observed is $4\text{mm}$ per blow and the combined temporary compression of the pile, cushion and the ground is $6\text{mm}$. As per Modified Hiley Formula, the ultimate resistance of the pile is

• A. $3000\text{kN}$
• B. $4285.7\text{kN}$
• C. $8333\text{kN}$
• D. $11905\text{kN}$

Answer 1

The correct option is B $4285.7\text{kN}$

Modified Hiley Formula

Ultimate resistance of pile
$=\frac{Wh\eta }{S+\frac{C}{2}}$

$W=weightofhammer$
$=50\text{kN}$

$h=heightoffall$
$=1\text{m}$
$=100\text{cm}$

$\eta =efficiency$
$=0.6$

$S=finalsetperblow$
$=4\text{mm}$
$=0.4\text{cm}$

$C=elasticcompressionofpile,cushionandground$
$=6\text{mm}$
$=0.6\text{cm}$

$Ultimateresistance=\frac{50\times 100\times 0.6}{0.4+\frac{0.6}{2}}=4285.7\text{kN}$