Seismic bearing capacity of a strip footing on rock slopes

Abstract

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, Nσ, are compared. For seismic problems, Nσfactors for different ground inclinations are presented for practical use in rock engineering.