Miller Piling brought in a vibrating hammer to install piles at a sensitive central London office development site.
The firm opted for the RF18 vibrating hammer from Piletec as a low-noise, resonance-free way to install piled foundations at the 30 storey development at 240 Blackfriars Road, for Great Ropemaker Properties.
The site on the South Bank of the Thames has a live Victorian brick railway viaduct on one side.
Miller Piling’s £1.2M subcontract with Mace involved installing 280 piles for a secant piled basement box, and 168, 750mm diameter reinforced concrete bored bearing piles next to the viaduct.
Poor ground conditions meant that foundations had to go deep, with the concrete bearing piles between 20m to 42m.
Variable ground in the upper layers meant that temporary steel casings were driven to around 12m before the piles could be bored in dry, stable clay.
Using an impact hammer carried the risk of causing structural damage and disruptive noise so Miller opted for the crane-suspended vibrating hammer.
The RF18 hammer’s eccentric moment is turned off during start-up and switched back on only once the mechanism has reached its operating frequency.