An Experimental Study of Seismic Bearing Capacity of Shallow Footings

In this paper, the results of an experimental investigation on the response of model shallow footings to horizontal accelerations are presented. The experiments were conducted on square and rectangular footings resting on or embedded in a dry sand and shaken in a shake box. The shake box was designed to subject the soil to simple shear conditions during shaking. Model footings, constructed from lead, were used to study the seismic bearing capacity. The influence of the magnitude and frequency of the horizontal accelerations, the static bearing capacity safety factor, the footing shape, the depth of embedment, and the relative density of the soil on the seismic bearing capacity were investigated. It is shown that the initial shear fluidization acceleration is the maximum acceleration sustainable by a shallow footing regardless of the static bearing capacity safety factor. Critical accelerations from limit equilibrium analyses do not compare favorably with the experimental results except when the change in angle of friction from cyclic densification was taken into account