Determining shallow foundation stiffness in sand from centrifuge modelling

Centrifuge modelling using sands excels for large deformation ultimate limit state (ULS) problems. Stiffness remains more challenging due to the inherent particle size effects that lead to displacements being incorrectly simulated. A series of modelling of models tests has been conducted to investigate the influence of the relative size between a vertically loaded shallow foundation and the mean sand particle size on the measured stiffness. The results highlight that the number of particles within a failure mechanism directly affects the observed stiffness. The number of particles can be estimated through taking the footing width to mean particle size ratio and a linear relationship relating this ratio and the foundation stiffness.