Investigating the Unseen Flow of Concrete in Deep Foundation Construction

Thomas Mitchell1, Chris Wilkes2, Chris Barker2, Duncan Nicholson2 1 Swansea University, Swansea, UK; 2 Ove Arup and Partners Ltd, London, UK Computation Fluid Dynamics (CFD) numerical modelling has proven to be a powerful tool for simulating the unseen flow of concrete in deep foundation construction. In this research, parametric studies are conducted to investigate different aspects of the tremie concrete technique. Concrete consistence, foundation design, and key execution assumptions such as cover zone size and pile diameter are simulated to reveal how they affect concrete flow mechanisms within bored piles. Flow features observed from the numerical simulations are then linked to the likelihood of physical defect generation. The open-source CFD software OpenFOAM is used to model the tremie concrete as a non-Newtonian Bingham fluid. A novel gravity-driven approach is implemented with a high-fidelity, 3D geometry to capture both the gravity-pour process of the tremie method and detailed flow around the reinforcement and cover zone. Reducing the cover zone size, increasing pile diameter, and using lower consistence concrete all correlate to an increase in severity of negative flow features – meaning an increase in likelihood of the generation of defects such as mattressing, voids and inclusions.