Statistical Evaluation of the Load-Settlement Response of a Multicolumn Composite Foundation

Abstract

This study examined a composite foundation that was improved by the joint usage of two types of columns: soil-cement and stone columns. The composite foundation that consists of soil-cement columns, stone columns, and natural soils is herein referred to as a multicolumn composite foundation (MCF). Explicit expressions of the equivalent modulus of the MCF under elastic and/or plastic conditions were considered. The spatial variability in the material properties of natural soils and soil-cement columns was taken into account during the calculation of the equivalent moduli. Through considerations of variability, the MCF settlement can be predicted in a statistical manner, thus enabling a reliability-based design for the composite foundation under the serviceability limit state. Finally, the reliability-based design methodology was shown to achieve a desirable balance between safety and economic considerations when designing the area replacement ratios of both types of columns in a MCF.