Abstract: The mechanical effect of the buoyancy acting on deep foundation in clay is studied by model experiment in this paper.There are two aspects in the experiment.One is to understand the disciplinarian of buoyancy with water level in clay.Another is to observe the dynamic process of buoyancy with time in clay.The results indicate that the measured buoyancy is less than the theoretic buoyancy calculated by Archimedes’s law.And the difference can be expressed as reduction coefficient.The reduction coef...