Deriving a design approach for spudcan penetration directly from cone penetrometer data relies heavily on the contrasting soil failure mechanisms that evolve around the objects during continuous penetration. This paper describes centrifuge modelling of penetration of a halfcone and a half-spudcan in a four-layer profile comprising sand-clay-sand-clay. The model half objects were penetrated against a window, with particle image velocimetry providing accurate resolution of the evolving soil failure mechanisms. For the half-cone, no soil plug was trapped at the base of the cone. The soil deformation was concentrated around the tip. In contrast, for the much flatter spudcan, a soil plug developed at the base of the advancing spudcan, with the height of the plug accumulating through trapping sand and clay, regardless of their strength, from layers above and below the advancing spudcan. A sand column was also formed above the advancing spudcan. The consequent effect on the penetration resistance profile was identified. It was confirmed that for establishing a direct calculation method for stratified sediments, the contribution of the evolving plug is the dominating distinguisher and needs to be accounted for.
Stefanus Safinus, M. S. Hossain, M. J. Cassidy, M. F. Randolph and M. A. Mohiuddin
Keywords: centrifuge modelling, clay, cone penetrometer, failure mechanisms, particle image velocimetry, sand, spudcan foundation
Publisher: DFI