Mechanistic investigation into the performance of stone columns constructed with riverbed aggregates in varied soil conditions

Stone columns are an efficient and economical ground improvement technique to enhance weak soils’ bearing capacity and settlement behaviour. This experimental study examines the performance of stone columns constructed with riverbed gravel as a sustainable alternative to conventional crushed stone in layered soil conditions. Laboratory-scale plate load tests were conducted in a cylindrical unit cell of soft clay, silt, and sand layers. Two identical stone columns (63 mm diameter, 250 mm length) were installed and tested under two loading conditions: entire cross-sectional and column-only loading. Results indicated that stone column installation significantly increased load-bearing capacity by up to 43% in clay, 25% in silt, and 27% in sand compared to untreated soils. In layered soil, the improvement reached approximately 34%. Columns constructed with riverbed gravel achieved 80–95% of the performance of those using crushed stone, demonstrating comparable stiffness and settlement reduction, though with slightly greater bulging near the surface. The study confirms that riverbed gravel offers a cost-effective and sustainable alternative for stone column applications, maintaining high structural efficiency while reducing environmental impact.