DuroTerra Dialogue: A low-vibration, driven piling system…

Is that even possible? The industry often associates driven piles with the exact opposite. Therein lies the paradox of the TRM Ductile Iron Pile system. Ductile Iron Piles are installed with an excavator-mounted hydraulic breaker hammer (i.e. demolition hammer) that delivers direct percussion (impact) energy to the pile head. While the energy per blow is much lower than a traditional diesel hammer, the hammer strikes at a much higher frequency to deliver the driving energy. The typical impact frequency ranges from 300 to 600 blows per minute – that’s 5 to 10 blows per second! But unlike a vibratory hammer used for some pile installations, the percussion energy remains direct vertical impact energy. The combination of the lower energy/blow and the higher frequency impact results in a system that rapidly drives the pile with minimal vibrations.

Substantial vibration data has been collected at various project sites to verify acceptable levels and also to provide project teams with information to assess the feasibility of using a Ductile Iron Pile solution. These data are summarized in our Tech Brief on Ductile Iron Pile Vibration and Sound. Measured peak particle velocities (PPV) are typically between 0.25 ips and 1.0 ips at distances of only a few feet from installation. Monitoring data from numerous sites are shown below.

Brooklyn, New York

Plans for a new 161,000 sqft movie studio required foundation and retaining wall support abutting an existing, vibration-sensitive retaining wall on a portion of the site. While ground improvement was planned for the majority of the project, Ductile Iron Piles were selected to limit vibration concerns in the critical areas. Grouted Ductile Iron Piles were installed through the fill and organic clay to develop working capacities of 40 tons (compression) and 19 tons (tension) through friction in the underlying medium dense to dense sand. Following successful load testing, a total of 195 piles were installed in 11 working days with no impacts to the retaining wall.