Engineering of ground with granular piles: a critical review

Granular piles/stone columns are one of the most commonly preferred ground engineering systems for improving a variety of weak soils, such as soft clays, loose sands, waste fills, and ash ponds. They are installed using a range of techniques, namely vibro compaction, vibro replacement, composer method, rammed stone columns, and geopiers, based on on-site conditions and availability of machinery. Granular piles improve the ground by densification especially in loose sands, by reinforcement in case of waste fills and ash ponds, by reinforcement and consolidation in case of soft clays, and mitigate damages from liquefaction by functioning as drains. The paper presents a critical review of developments related to granular piles encompassing recent analytical, experimental, numerical studies, and field investigations of their compressive, uplift, and seismic responses. Three well-documented case histories of an embankment, a mechanically stabilized earth wall, and a liquid storage tank on granular pile-engineered ground are presented to illustrate their versatility.