Performance of Stone Columns With Alternate Granular Materials in Different Types of Soils-Paper

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The study evaluates copper slag columns (CSCs) as a sustainable alternative to ordinary granular columns (OGCs) for ground improvement. PLAXIS 2D finite-element analyses compared column performance in homogeneous sand, soft clay, and two layered soil profiles, examining load capacity, settlement, bulging, drainage, and column length-to-diameter (L/D) ratio. The numerical approach was checked against experimental stone-column results.<br /><br />CSCs generally improved load-bearing performance relative to untreated ground and, in the reported homogeneous-soil comparisons, outperformed OGCs. Load-capacity improvement was 102.7% for CSCs versus 66.8% for OGCs in clay, and 25.5% versus 4.3% in sand. The paper reports that CSCs reduce settlement comparably to or better than OGCs. In sand, CSCs showed about 13% greater bulging, but this did not materially diminish their performance; in clay and layered soils, their peak bulging was slightly lower than that of OGCs.<br /><br />Increasing L/D improved performance in clay up to a critical ratio of 5 for CSCs and 3 for OGCs, beyond which gains were limited. L/D effects were not assessed in sand because of its immediate drained response. Both column types accelerated pore-pressure dissipation and consolidation compared with untreated clay, although OGCs drained faster because of their higher permeability.<br /><br />The findings support copper slag as a technically promising way to reuse industrial waste and reduce reliance on natural aggregates. However, the conclusions are based on numerical modelling; the authors recommend large-scale and field validation, as well as investigation of long-term durability, construction effects, and environmental and economic performance.

Keywords

copper slag columns

ordinary granular columns

ground improvement

PLAXIS 2D

finite element analysis

load-bearing capacity

settlement reduction

bulging behavior

pore pressure dissipation

sustainable industrial waste reuse