Upper Bound Analysis of the Effect of Footing Roughness on N γ and the Failure Mechanism of a Strip Footing

The effect of footing roughness on the bearing capacity factor Nγ and failure mechanism of a strip footing on pure sand were examined using an upper bound finite element method with rigid translatory moving elements (UBFEM-RTME). The analysis was performed with different combination values of the footing–sand friction angle (δ) and the sand friction angle (ϕ). The magnitude of Nγ is found to continuously increase with increasing δ/ϕ and ϕ. The obtained failure mechanism primarily consists of a completely curved trapped wedge and a mesh-like failure zone, with the exception of the case where δ/ϕ = 0. The sizes of the failure zone and the curved wedge, briefly by four introduced geometric parameters, increase with an increase in δ/ϕ and ϕ. The values of δ/ϕ exhibit a particularly pronounced effect on Nγ and associated failure mechanism, especially for high values of ϕ with small values of δ/ϕ. The present results match quite well with those results available in the literature.