Bearing Capacity is the maximum contact stress that a soil or rock mass can sustain from a foundation without undergoing shear failure. It is a geotechnical strength parameter that defines the load-carrying capability of the supporting ground at the soil–foundation interface. In formal terms, bearing capacity corresponds to a limit equilibrium condition in which the applied stresses mobilize the available shear strength of the soil along a failure surface beneath the footing.
In classical shallow foundation analysis, the ultimate bearing capacity is governed by three primary contributions: soil cohesion, surcharge (overburden pressure at foundation level), and the self-weight of the soil within the failure mechanism. The resulting expressions are derived from limit equilibrium theory and assume defined boundary conditions, soil homogeneity, and specified loading geometry.
There is no single universal “basic formula” for bearing capacity that applies to all soils and foundation conditions. In practice, the term “bearing capacity” is often used in two distinct senses: ultimate bearing capacity (a theoretical failure stress) and allowable bearing capacity (a reduced design stress incorporating safety factors and, where applicable, settlement limitations). The allowable value governs foundation sizing in service conditions and is selected to ensure both strength adequacy and acceptable deformation performance. In summary, bearing capacity is the stress threshold at which the soil, foundation system transitions from stable equilibrium to shear failure. It is a strength-based parameter derived from established soil mechanics principles and forms the basis for evaluating the safety and performance of shallow foundation systems.
