Upper-Bound Solutions for Bearing Capacity of Foundations

The static and seismic bearing capacity problem of shallow strip footings is investigated. Two kinematically admissible failure mechanisms M1 and M2 are considered in the framework of the upper-bound method of the limit analysis theory. The M1 mechanism is symmetrical, and it permits the calculation of the bearing capacity in the case of no-seismic loading. It is composed of a triangular active wedge under the footing and two radial shear zones composed of a sequence of rigid triangles. The M2 mechanism is nonsymmetrical and is composed of a single radial shear zone. This mechanism permits the calculation of the bearing capacity in the presence of seismic loading. Quasi-static representation of earthquake effects using the seismic coefficient concept is adopted. The solutions obtained are rigorous upper-bound ones in the framework of the limit analysis theory. The numerical results of the static and seismic bearing capacity factors are presented in the form of design charts for practical use in geotechnical engineering. These results are compared with results of other authors.