Field measurements of airborne noise emission during impact piledriving on land and the effect of a reduced stiffness at the impact interface-Paper

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The study evaluates whether reducing stiffness at the hammer–pile interface can lower airborne noise during impact pile driving. A hydraulic spring element (“Pulse”) was fitted between a 90-kJ hydraulic hammer and steel tubular piles. By cushioning the impact, the element reduces peak force and extends impact duration, introducing stress waves into the pile more gradually.<br /><br />Three similar piles were installed: one using the conventional hammer and two using the Pulse system. Noise was measured 41.5 m from the pile, while hammer energy, blow count and Pulse settings were monitored. For a comparable segment driven at roughly 80 kJ and around 40 blows per 0.25 m, the Pulse system reduced equivalent noise levels across nearly the entire measured frequency range. The segment’s total LAeq was 8.2 dB(A) lower with Pulse than without it. Simulations also indicated reduced force and velocity content at higher frequencies.<br /><br />The results show that a hydraulic spring can substantially reduce airborne noise without requiring pile encapsulation. Hypothetical scenarios suggest that partial use of Pulse can still provide meaningful reductions: using it for 25%, 50% or 75% of driving was estimated to lower noise by 2.1, 4.3 or 6.6 dB(A), respectively.<br /><br />The authors recommend further investigation of how changes in impact-force characteristics relate to noise reduction across frequencies.

Keywords

impact pile driving

airborne noise reduction

hydraulic spring

hammer-pile interface

pulse system

steel tubular piles

equivalent noise levels

stress waves

impact force

noise mitigation