Centrifuge Testing of Rocking Foundations on Saturated Sand and Unconnected Piles : The Fluid Response

Current research has shown the capabilities and improved seismic performance of rocking shallow foundations for bridges, and much work has been done for implementation of such a mechanism in industry. By properly reducing the size of the footing, rocking behavior due to seismic loading can occur about the footing base. It has been shown experimentally that rocking foundations on competent soils can reduce seismic ductility demand on bridge columns and improve bridge performance. One concern of rocking systems is the potential for significant settlement accumulation in poor soil conditions. This research explores soil, footing, and structural response of similar bridge structures on poor, liquefiable, and saturated soil conditions in addition to the effectiveness and practicality of using unconnected piles as a potential settlement mitigation technique. A centrifuge test series showed rocking foundations in saturated sand over a liquefiable soil layer not only experience the traditional deformations from liquefaction, but are also susceptible to additional deformations such as suction and erosion around the footing.