Sheet Pile Tuned Mass Damper for Construction Noise Control

Sheet piles are often used for underground retaining structures. For dense geology, vibratory driven method is more cost-effective than press-in driven method, but noisier. Conventional mitigations such as noise barrier or enclosure are not applicable due to the large size of pile wall (generally >12m high and >10m width). Acoustic camera images revealed that noise radiation was dominant at 630Hz to 2000Hz and mainly came from the sheet-pile wall rather than the vibratory exciter. Vibration response measurement showed the sheet piles had two major resonance modes at 1000 and 2000Hz. An innovative noise mitigation method was developed with 14 nos. of tuned mass dampers (TMD) distributed along a 5m long aluminum tube for vibration energy dissipation at the pile wall. Specific magnetic mounts were developed for quick and easy attachment of the TMDs at the construction site. In the site test, total 6 aluminum tubes (i.e., 84 TMDs) were mounted to the 1st, 2nd and 3rd piles adjacent to the driven pile on both sides. Vibration reduction was measured ~9 to 14dB at the pile wall. Noise reduction was measured 7 to 9dB(A) at 2 noise monitoring locations (~7m and ~22m from the pile wall).