Hamilton Drive, St John’s Wood is an impressive development of ten town houses and a luxury villa. The houses have two levels of basement providing parking, home cinemas, gyms and a swimming pool. The site was previously occupied by 140 disused garage units. The new buildings comprise reinforced concrete walls and slabs within a secant piled basement box.
Byrne Looby provided detailed civil and structural engineering design for PJ Carey under a design and build contract. The role covered both permanent and temporary works. With a long site boundary, 23 party wall awards were required before the basement excavations could begin. ByrneLooby provided the structural input for these awards.
The original design employed a raft for the foundations with tension piles to resist heave and hydrostatic pressure. However, ByrneLooby undertook careful modelling of heave and settlement for the site and surroundings using Flac 3D software. This gave a better estimate of final heave and settlement and showed that with the introduction of a drainage blanket to reduce hydrostatic uplift and stiffening of the basement box to cope with minor differential heaves the tension piles could be eliminated. The savings from this redesign were critical in PJ Carey winning the project.