Experimental study on the bearing capacity of adjacent footings on sand subject to interference effects

A series of model tests were conducted to investigate how the bearing capacity of adjacent footings on sand varies with interference effects. The spacing ratio between adjacent footings, the embedment depth of the footings, and the relative density of the soil were selected as key parameters, and the interference effects were quantitatively analyzed using an efficiency factor defined as the ratio of the bearing capacity of adjacent footings to that of a single footing. The model ground was prepared using Han River sand with relative densities of 40% and 80%, and the tests were conducted by varying the spacing ratio between adjacent footings from 0 to 3. The results of the model tests revealed that the bearing capacity of adjacent footings on sand was greater than that of a single footing because of interference effects. For all the test results, both the bearing capacity and the efficiency factor reached their maximum values at a spacing ratio of approximately 0.5 and then gradually decreased with increasing spacing ratio. In addition, the bearing capacity of adjacent footings generally increased with increasing footing embedment depth and soil relative density. The trend of the efficiency factor with respect to the spacing ratio between adjacent footings in this study showed overall agreement with previously reported results. The findings of this study are expected to provide fundamental data for establishing rational footing layouts that consider the effects of interference in the design of shallow foundations on sand.