Ordinary and Encased Stone Columns with Two Different Relative Densities

Abstract

Stone columns technique is most commonly used in increasing bearing capacity, reduces and controls the compressibility and accelerates the rate of consolidation of soft saturated clay. During the last four decades, the technique has been utilized worldwide and proved successful results. Several modifications have been proposed to increase the efficiency of this technique such as addition of additives, use of special patterns of reinforcements, encasing the stone columns with geonet or geogrid to provide extra confinement that enhances the bearing capacity and reduces the settlement drastically without compromising its effect as a drain. The present paper focuses on the behavior of soft saturated clay reinforced with ordinary and geogrid encased stone columns. The investigation was performed both experimentally through small scale models and through numerical techniques. The influence of relative density of the back fill material and the presence of the encasement are the main parameters investigated. Ordinary stone columns revealed an increase of 20% in the carrying capacity when the relative density of the backfill stone aggregates increased from 23% to 71%, furthermore the efficiency of the encasement was more pronounced at lower relative density.

Keywords

• numerical analysis
• geogrid encasement
• bearing improvement ratio
• soft clay
• stone columns
• relative density