Seismic bearing capacity of shallow foundations near slopes using the upper-bound method

Abstract

The seismic bearing capacity factors of spread and embedded foundations near slopes have been analytically investigated. The pseudo-static approach was used and the seismic forces consisted of a horizontal load applied to the foundation and the inertia of the soil mass. The upper-bound method of limit analysis was employed and a non-symmetrical failure mechanism was proposed. This mechanism comprises a triangular active wedge, a logarithmic spiral shear zone and a passive wedge. The shear transfer coefficient was introduced to calculate the seismic bearing capacity of spread foundations with variable shear transfer at the base of foundations. The validity of the results from the present analysis was confirmed by comparing with the results proposed by other investigators. Finally, the lowest upper-bound solutions of the seismic bearing capacity factors of shallow foundations near slopes were presented in the form of design charts for practical use in geotechnical engineering. It has been shown that the seismic bearing capacity factors reduce considerably with the increase of horizontal seismic coefficient. In addition, the magnitude of bearing capacity factors decreases further with increase in slope inclination and increase with the embedment and the distance of slope crest from the beginning of loading.