Vertical bearing capacity factors for conical footings on sand

The drained bearing capacity of a circular foundation on the surface of frictional material, loaded by a central vertical load, is usually calculated using the well-known procedures described by Terzaghi (1943) and formulated as

where R is the footing radius and γ′ is the effective unit weight of the soil. Various authors have proposed appropriate values for the dimensionless bearing capacity, N_γ. However, most values are calculated for strip footings, and are applied to circular foundations by scaling using an empirical shape factor (usually taken as 0·6).

The...