This paper has introduced a new computer program, ABC, for calculating the vertical bearing capacity of strip and circular foundations on weighty Mohr-Coulomb (c-φ-γ) soil using the method of characteristics. A linear variation of c with depth is catered for. The governing equations and boundary conditions have been described in detail, as have the procedures used to construct 'incomplete' lower bound stress fields for both smooth and rough footings. Previous research suggests that for the classical case of associated flow (ψ = φ) a collapse load calculated in this manner is in fact exact, i.e. the incomplete stress field can be extended throughout the soil mass in a statically admissible manner, and a coincident upper bound collapse load can be obtained. ABC allows fast, semi-automated refinement of a mesh of characteristics, and it can therefore be used to produce highly accurate benchmark solutions as well as 'coarse' bearing capacities for routine analysis and design.
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