Soil-Rounding Effect on Embedded Rocking Foundation via Horizontal Slow Cyclic Tests

Abstract

The rocking behavior of a shallow foundation of a bridge pier has emerged as an effective mechanism for reducing the seismic load on the superstructure during a strong earthquake. However, a lack of understanding regarding the rocking behavior of shallow foundations has hindered the application of the rocking foundation design philosophy to construction. In this study, the soil-rounding effect on embedded foundations was evaluated to increase understanding of the rocking mechanism. A centrifuge apparatus was used to conduct horizontal slow cyclic tests on an embedded shallow foundation model for three different slenderness ratios (i.e., structure height divided by foundation length) at a centrifugal acceleration of 2 g. The soil-rounding phenomenon was examined according to variations in the soil pressure under the foundation during cyclic loading, and the shape of the rounded soil surface was evaluated as a function of the slenderness ratio. The ultimate moment capacity of the shallow foundation was observed to increase with the side soil pressure; this was verified by comparing the side soil earth pressure with the overturning moment. The rocking mechanism of the embedded shallow foundation was evaluated by focusing on soil rounding.