GATE 2019 CE (CE2) – Question 64
An 8 m long, 0.2 m diameter timber pile is driven with a 20 kN drop hammer falling 1.5 m. Total penetration in the last five blows is 40 mm. Use the Engineering News Record expression with safety factor 6 and energy-loss set allowance 2.5 cm. Find safe pile capacity (kN), to two decimal places.
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Correct answer: 151 to 152
Explanation
Mean set is 40/5 = 8 mm = 0.008 m per blow. Energy-loss allowance is 0.025 m. ENR safe load is $$Q_s=\frac{Wh}{F(S+C)}=\frac{20(1.5)}{6(0.008+0.025)}=151.52\ \mathrm{kN}.$$ Use metres consistently.