Soil–structure interaction in a combined pile–raft foundation – a case study

The present work explains the use of a piled-raft foundation in a raw materials storage building in South Bà Rịa–Vũng Tàu Province of Vietnam. The proposed foundation comprises an 81 m by 55·5 m raft that connects 581 precast hollow concrete piles 20 m long with 400 mm outer diameter. The proposal takes into consideration a specific in situ soil profile and a loading scenario. After the effectiveness of a single bay of the foundation had been checked, the entire foundation system was modelled using finite-element-based geotechnical software to enable a detailed soil–structure interaction analysis. Field pile load test data were used to validate the finite-element model. Various loading conditions, such as all compartments full to all compartments empty, were considered in the analysis. The results of the analyses indicate the importance of the raft in sharing 23–31% of the total vertical load. The results obtained – such as vertical settlement, differential settlement, tilt in the raft and axial load in the piles – were used in the final design. These results can also be used in similar practical applications.