Bearing Capacity of Shallow Foundations: Rigid versus Flexible Models

The effect of stiffness of a shallow foundation on its bearing capacity has hardly been studied, although it is technically possible to construct a foundation with durable flexible interface. Reported here are the results of a preliminary experimental study aimed at observing the behavior of small-scale flexible and rigid foundation models, resting on dense sand, at their ultimate load-bearing capacity. The results indicate that reducing the foundation's stiffness at its soil interface may significantly increase its load-bearing capacity. This increase, however, is associated with increased settlement. No consistent differences in the slip surface geometries were observed. It is suggested that the apparent increase in bearing capacity is due to differences in the contact pressure distributions combined with the phenomenon of progressive failure. Upon further verification of this work's observations, its results are potentially applicable to foundations of structures such as mechanically stabilized earth or retaining walls founded on strip footing, where design is controlled by a factorized load-bearing capacity value.