Seismic bearing capacity of a strip footing on rock slopes

Most of the seismic calculations currently used for the evaluation of seismic bearing capacity are formulated in terms of a linear Mohr-Coulomb failure criterion. However, experimental evidence shows that a nonlinear failure criterion is able to represent fairly well the failure of almost all types of rocks. In this paper, a nonlinear Hoek-Brown failure criterion is used to estimate the seismic bearing capacity factor of a strip footing on rock slopes in a limit analysis framework. Quasi-static representation of earthquake effects using a seismic coefficient is adopted for the seismic bearing capacity calculations. A linear Mohr-Coulomb failure criterion, tangent to the nonlinear Hoek-Brown failure criterion, is used to derive the objective function that is to be minimized. Upper-bound solutions are obtained by optimization. For static problems, bearing capacity factors related to uniaxial compressive strength, N-sigma, are compared. For seismic problems, N-sigma factors for different ground inclinations are presented for practical use in rock engineering.