Buoyancy force on shallow foundations in clayey soil: An experimental investigation based on the “Half Interval Search”

Groundwater buoyancy force, calculated by using the Archimedes' Principle, provides a fundamental basis for the anti-flotation design of buoyant structures. Owning to the limitations of large-scale field measurements and small-scale laboratory model tests, previous practitioners indicated that the measured buoyancy force was slightly different from the calculated Archimedes' buoyancy force. However, this argument is still questionable in the academia. This study hence introduced an experimental investigation of groundwater buoyancy force on shallow foundations embedded in saturated clay ground based on the “half interval” search method. By setting the weight of model buckets in an “arithmetic sequence”, the groundwater buoyancy force was obtained based on the average weight of the “heaviest” model bucket that floated and the “lightest” model bucket that did not float under the same hydrostatic uplift loading. The proposed “half-interval search” method has many advantages, i.e., didn't rely on any instrumentations, avoided limitations of devices/sensors, and maintained high quality of test accuracy. In addition, the complete test processes were recorded, during which the buoyancy force change could be observed lively. Test results demonstrated that the measured buoyancy force on foundations in clay ground was smaller than the theoretical buoyancy force, which is consistent with the large-scale field measurements, indicating that the proposed half interval search method is reliable and robust.