Upper bound kinematic approach to seismic bearing capacity of strip foundations resting near rock slopes

The present paper evaluates the seismic bearing capacity of a strip footing lying near the edge of a rock slope. Resorting to the framework of the limit analysis kinematic approach formulated in the context of pseudo-static method, the analysis assesses the reduction in ultimate bearing capacity (UBC) provoked by the combined effects of the proximity of rock slope and seismic loading. The nonlinearity of the strength properties of rock material is modeled by means of a modified Hoek-Brown failure criterion. At the structure level, the closed-form expressions derived for the support functions associated by duality with such a failure criterion allow deriving rigorous upper bound solutions for the UBC. Particular attention is paid to the description and implementation of the generalized multi-wedge failure mechanism, which proves efficient to predict the stability conditions. The approach is then applied to investigate the effects of relevant geometry, strength and loading parameters. The approach accuracy is evaluated by comparison of the obtained predictions with existing limit analysis results, as well as with lower and upper bound finite element solutions, thus emphasizing the proposed approach efficiency to evaluate the reduction in UBC induced by slope proximity in the static and seismic cases.