A multi-storey redevelopment was proposed on a site previously occupied by a car park and light structures, underlain by Made Ground, River Terrace Deposits, and London Clay from approximately 4 m depth.
GCG supported the client in developing a cost-effective and sustainable alternative to a fully piled foundation. The solution comprised a single ground-bearing raft supported by settlement-reducing piles across the site, designed to carry all new buildings. To facilitate this, GCG devised a simplified yet robust analytical procedure for modelling rafts with settlement-reducing piles—enabling the use of CFA piles in place of the traditionally specified bored piles.
The approach involved iterative geotechnical and structural analyses, simulating a ground-bearing raft with column loads partially offset by pile capacity. At each iteration, the number and layout of piles were optimised to achieve an efficient and balanced distribution.
This innovative design led to a significant reduction in both cost and embodied carbon—achieving a 40% reduction in pile numbers compared to a fully piled solution, with shorter and smaller piles contributing to the overall sustainability of the project.
Publications
Gasparre et al. (2020). Developing a simplified model for the design of rafts with settlement reducing piles. Proceedings of the Piling 2020 Conference. ICE Publishing. pp.145-149.
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