Dynamic response of circular footing: Findings from experimental soil-foundation interactions

One of the fundamental problems in dynamic soil-foundation interaction is the characterization of the dynamic response of surface foundations resting on a soil medium subjected to time-dependent loads. In this study, the horizontal impedance function for circular footings is investigated using physical model tests on a finite thickness soil stratum over bedrock. The tests were conducted inside a steel container and filled with uniform Babolsar sand using an air-pluviation technique, achieving a relative density of approximately 54%. A 10 cm thick layer of sawdust was employed around the container and the sand to simulate an infinite half-space. Concrete slabs, with a thickness of 15 cm, were also used to represent the bedrock beneath the sandy layer. The system was subjected to two-way perpendicular co-phase horizontal loading vibrations. The results indicate that both the dynamic stiffness and damping coefficient increase with a rising embedment ratio. Additionally, the increase in the footing mass has a minimal effect on the dynamic response of the circular footing.