Bearing capacity factorNγfor ring footings using the method of characteristics

The bearing capacity factor N γ was determined for both smooth and rough ring footings using the method of stress characteristics. The analysis was based on the assumption that for a rough footing the friction angle (δ) between the footing base and underlying cohesionless material increases gradually from zero along the axis of symmetry to ϕ along the outer edge of the footing. The value of N γ was found to decrease significantly with an increase in r i /r o , where r i and r o are the inner and outer radii of the ring, respectively. For larger values of ϕ, the magnitude of N γ for a rough footing was seen to be significantly higher than that for a smooth footing. The obtained results were compared with those available in the literature.