Managing construction noise levels is one of the main challenges of each developer. Recently, Shanghai ICE visited the office of Acoustic Innovations LTD in Hong Kong to learn more about their sound emission reducing solutions. AI offers two products that we want to share in this article. The first reduces the sound emissions during the panel driving of sheet piles, and the second is a highly effective and easy to set-up noise barrier product.

Sheet pile tuned mass damper for construction noise control

A major source of sound emissions during sheet pile installation by vibratory hammer, is the radiated noise from vibrations in the sheet pile panel wall. Panel installation is commonly used for driving long, welded together, sections of sheet piles; by pre-loading the sheet piles in their interlocks it ensures good verticality of the entire wall. The interlocked piles do however add to the sounds created on the construction site. The dominant sound frequencies that occur during driving range from 630Hz to 2000Hz. Acoustics Innovation Limited has developed a Sheet Pile Tuned Mass Damper (Sheet Pile TMD) to dissipate the vibration energy in the of sheet pile by a tuned mass damping mechanism that is attached by magnets directly to the sheet piles, thereby mitigating the noise generated from the sheet piling work.

Together with contractor Build King AI proved the concept in a field demonstration. Six sets of 5m long Sheet Pile TMD were installed on a 12m high x 4m wide sheet pile wall driven by an ICE 815D vibratory hammer. The Sheet Pile TMDs were tuned to absorb vibration energy from 630 Hz to 1250 Hz by adjusting the stiffness of the resilient layer and the size of the oscillation masses. From the on-site trial results, the Sheet Pile TMDs achieved ~9-14dB vibration reduction at the 1st, 2nd and 3rd piles next to the driven pile and ~7dB noise reduction at a distance of 7m and 22m from the pile wall. This is a significant reduction.

THE SHEET PILE TUNED MASS DAMPER MECHANISM

The design of Sheet Pile TMD and installation method is illustrated in Figure 1 - Figure 3. Each damper consitst of multiple oscillation masses made by stainless steel block sandwiched between resilient layers and magnet. Most of the vibration energy of the sheet pile is transferred to the oscillating masses of Sheet Pile TMD and dissipated by hysteresis in the resilient layers. The natural frequencies of the oscillating masses can be tuned independently to provide effective damping. Tuned mass damping mechanism is effective for sheet pile vibration in the frequency range of 630Hz to 1250Hz.

The complete article describing the research can be downloaded here.

A RETRACTABLE NOISE BARRIER 27dB(A) NOISE REDUCTION*

SilentUP® is Acoustic Innovations LTD’s patented retractable noise barrier for construction works and outdoor music events. It can be easily installed and mobilized by workers without using any machines. No concrete foundation is required, and the installation process is quiet enough to be conducted even at nighttime. The panels are installed upwards from ground level and connected by magnetic gap sealing. The gap sealing is designed to allow gusts of wind to pass through the barrier so as to leave the wall unaffected in windy weather conditions. The noise barriers have been widely adopted in Hong Kong. Visit Ai’s website for the job references www.aihk.hk/SilentUP/reference.

Get in touch with ICE with your construction challenges, we are excited to pass on practical wisdom of 50 years of piling experience!