Early design analysis identified that a CFA piled raft foundation system offered the most reliable and efficient approach for the development. This integrated system combines piling and reinforced concrete raft slabs as part of the substructure works, enabling structural loads to be transferred safely into the underlying ground while maintaining a stable and continuous base for the building. By adopting a piled raft solution, SPEEDECK was able to optimise load distribution and reduce the risks typically associated with ground variability. This concept also supports a more streamlined installation sequence, providing the client with increased programme certainty and simplified site coordination.
Concept Design
Design Engineering
The engineering design incorporated a 300mm reinforced concrete piled raft slab, sized to accommodate the structural loading of the building. To address potential ground movement risks, 225mm voidformers were incorporated within the slab build-up where heave protection was required. The structural design utilised engineer-provided load information to establish an efficient piling arrangement capable of safely supporting the superstructure. The foundation system achieves a maximum safe working load of 340kN, with pile lengths ranging approximately between 8.0m and 12.0m to reach suitable bearing strata. The overall substructure solution provides a total raft slab area of approximately 470m², forming a continuous structural platform that integrates the piling system with the reinforced raft slab to ensure reliable load transfer and long-term performance.
Construction
The substructure works were designed to enable efficient installation through a coordinated sequence of piling followed by raft slab construction within nine weeks. This integrated approach simplifies site logistics and reduces the number of construction interfaces, helping maintain programme certainty. By delivering the piling and structural slab as a single substructure package, SPEEDECK ensured consistent quality control and improved buildability across the development.
