Journal Of The Faculty Of Engineering And Architecture Of Gazi University, vol.28, no.1, pp.187-197, 2013 (Peer-Reviewed Journal)
Traditionally, for footings on cohesionless soils, the bearing capacity factor N-gamma is modified if an underlying rigid layer exists within a depth (H) less than or equal to the width of the footing (H <= B). However, the validity of this practice has been challenged by some recent studies, which indicate that this modification should be applied for rigid layer depths of up to three times the width (H = 3B) for circular and square footings. In addition, there is no consensus on whether the shape factors should be modified for this condition as well, and if so, how. In this study, laboratory test results of axially loaded rigid square and rectangular footings on sand underlain by rigid bases at five different depths are presented. The results are discussed within the framework of the limiting value of H/B for which the bearing capacity should be modified considering the effect of the footing shape as well.