Behavior of granular column supported gabion-raft foundation

Abstract

Soft clays exhibit insufficient bearing capacity and experience excessive settlement under load. To mitigate these effects, various ground improvement techniques are employed, with Granular Columns being a commonly used and effective approach. They are frequently implemented in soft clayey soils to enhance the bearing capacity of the native soil between the columns and promote pore water pressure dissipation through soil squeezing. However, in very soft clays, stone columns can lose their structural integrity and encounter drainage issues due to clogged voids at the clay-column interface. To address these limitations, the Ordinary Stone Column (OSC) technique was modified by encasing the granular materials within a Geogrid Encasement. This modification improves the bearing capacity of the encased stone columns without compromising their drainage capacity. Furthermore, the inclusion of a gabion on top of the stone columns, consisting of granular materials enclosed within geogrid, helps distribute the load evenly among the stone columns. In this study, a comprehensive investigation has been conducted using FE analysis with PLAXIS3D. The problem geometry has been modeled as a 3D strip in PLAXIS, and a parametric study has been performed to analyze the impact of various factors such as the properties of the soft soil (c and ϕ), angle of friction of the stone column material (ϕ), length of encasement, column spacing, geogrid and gabion stiffness, and embankment material density. This analysis aims to enhance our understanding of the physical performance of the stone columns in different scenarios.