A 40 x 40 cm reinforced concrete pile 20 m long is driven through loose sand and then into dense gravel to a final set of 3 mm/blow, using a 30 kN single-acting hammer with a stroke of 1.5 m. Determine the ultimate driving resistance of the pile if it is fitted with a helmet, plastic dolly and 50

Question

A 40 x 40 cm reinforced concrete pile 20 m long is driven through loose sand and then into dense gravel to a final set of 3 mm/blow, using a 30 kN single-acting hammer with a stroke of 1.5 m. Determine the ultimate driving resistance of the pile if it is fitted with a helmet, plastic dolly and 50 mm packing on the top of the pile. The weight of the helmet and dolly is 4 kN. The other details are: weight of pile = 74 kN; weight of hammer = 30 kN; pile hammer efficiency $\eta_{h}=0.80$ and coefficient of restitution $C_{r}=0.40$ .

Use the Hiley formula. The sum of the elastic compression $\bar{C}$ is

$\bar{C}=c_{1}+c_{2}+c_{3}=19.6 mm$ .

Use the Hiley formula. The sum of the elastic compression [latex]\bar{C}[/latex] is

[latex]\bar{C}=c_{1}+c_{2}+c_{3}=19.6 mm[/latex].

Accepted Answer

Hiley Formula

Use Eq. (15.59)

[latex]Q_{u}=\frac{\eta_{h} W h}{s+C} imes \frac{1+C_{r}^{2} R}{1+R}[/latex] (15.59)

[latex]Q_{u}=\frac{\eta_{h} W h}{s+C} imes \frac{1+C_{r}^{2} R}{1+R}[/latex]

where [latex]\eta_{h}=0.80, W=30 kN , h=1.5 m , R=\frac{W_{p}}{W}=\frac{(74+4)}{30}=2.6, C_{r}=0.40, s=0.30 cm[/latex].

Substituting we have,

[latex]Q_{u}=\frac{0.8 imes 30 imes 150}{0.3+1.96 / 2} imes \frac{1+0.4^{2} imes 2.6}{1+2.6}=2813 imes 0.393=1105 kN[/latex]

Question 15.22: A 40 x 40 cm reinforced concrete pile 20 m long is driven th...

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