Ove Arup & Partners International Limited, Warsaw, Poland
Geotechnical design process of a barretted raft foundation for a high-rise building in Warsaw is presented with the emphasis on comprehensive site and laboratory investigation allowing for precise assessment of geotechnical design parameters. The new development is being constructed at the location of former structure comprising two level basement surrounded by diaphragm walls along the site perimeter. The existing diaphragm walls and part of the original foundation raft are re-used in the new foundation scheme with new foundation raft cast onto the remaining section of the former one. Barrettes are designed as settlement reducing members below the core of the structure with application of base pre-stressing. The ground profile comprises made ground, two series of boulder clays underlain by a very dense sandy formation resting upon Tertiary subsoil represented by high plasticity clays. Soil-structure interaction analysis of the entire foundation system with application of 3D numerical analysis is described and results analysed. A thesis is formulated that adequately utilised sophisticated analysis methods when supported by high quality geotechnical investigation may lead to time and cost savings during the design process. Such sophisticated approach utilising numerical methods shall become a standard approach for types of development like high rise buildings, complicated and deep excavations, tunnels"