AMEC PILING is installing a retaining wall and piled foundations for the new Blackfriars House Hotel in London as part of a five month contract worth £1.5M.
The retaining wall consists of 200, 900mm diameter secant bored piles (100 male and 100 female). Of these, 150 piles are an average depth of 24m, with the remaining 50 being sunk to around 32m.
The contractor, working for main contractor Sir Robert McAlpine, is also installing 41 load bearing piles for the main structure to 32m depth. These vary between 900mm and 2.1m in diameter. And part of the works include drilling 1900mm diameter casing to depths of 12.5m.
Ground conditions are fill over London Clay. Piling is being carried out using a BSP 335T hydraulic drilling rig. This self-erecting multipurpose machine can form both rotary bored and CFA piles and as a high torque output of 250kNm. It can also jack itself up allowing the under- carriage to be rotated, making it suitable for restricted sites.