Reinforcement of piling platforms with geogrids over dewatered docks with very soft soils: Wood Wharf, London

Abstract

Wood Wharf is a major redevelopment of 23 acres designed to provide residential and office buildings as well as public spaces for shops, restaurants, parks and community uses. The development is located on the Isle of Dogs, Canary Wharf, London. This paper describes the design and results of the piling mats required to construct the buildings in the area of the South Dock, where 14,000m2 of land had to be reclaimed. Cofferdams were installed to create a watertight retaining structure to facilitate dry construction methods in the reclaimed area behind the new quay wall. To construct the different buildings, CFA and LDA piles between 8m to 34m deep were installed for the foundations. The soil profile primarily comprised Made Ground, Dock Sediments and River Terrace Deposits with very low undrained shear strengths between 2.5 to 42 kPa. The rigs to be used on site were 225 tons with applied pressures in the range of 300 to 470kPa and loadings of more than 1500kN. A series of reinforced piling mats were required to support the heavy rigs and reduce the applied pressures over the foundation soil. The design of the working platforms reinforced with geogrids was conducted in two stages, first to improve the modulus of the platform using recycled granular material, and second to provide safe platforms to support the heavy rigs.