Experimental study on buoyancy acting on deep foundation in clay

Scientific approaches to deep foundation design have advanced enormously in recent decades. Whilst improvements have been made in designing pile foundations, the definition of buoyancy acting on such a foundation is not straightforward. The mechanical effect of the buoyancy acting on a deep foundation in clay is studied by physical modelling in this paper. There are two key points. One is to understand the effect on buoyancy of water level another is to observe the development of buoyancy with time. The results indicate that the measured buoyancy is less than the theoretical buoyancy predicted by Archimedes's law. The buoyancy difference can be expressed as a reduction coefficient, and it is found that the magnitude of this coefficient increases gradually with time, in spite of the variability of the water level, from within the range of 0.30 - 0.40 to between 0.65 and 0.72 ultimately.