Effects of Base Roughness on the Bearing Capacity and Settlement of Strip Footings in Sand

Abstract

The effects of base roughness on footing bearing capacity in sand are well recognized; nevertheless, detailed experimental studies to quantify such effects are sparse. Therefore, this paper investigates the effects of base roughness on strip footing bearing capacity in sand. Two types of sand were used in the study—dune sand and Leighton Buzzard sand—to assess the effects of base roughness on strip footing bearing capacity. Laboratory models were used in the study. The base friction between the bottom of the footing and the sand was varied in steps from a minimum value up to the internal friction of the sand. Greater base friction raises the bearing capacity and decreases the settlement. Leighton Buzzard sand had higher bearing capacity than dune sand because of its greater relative density and larger particle size. The two sands consist of subrounded particles, though the particles of dune sand are more platy and elongated which could have contributed to the smaller bearing capacity of dune sand compared to that of Leighton Buzzard sand. The effect of base roughness on the bearing capacity is accounted for through the bearing capacity factor (Nγ), and an equation is proposed for this factor.