Numerical investigation of the consolidation behaviour of soft organic and inorganic clays stabilised with alkali-activated material deep mixed columns

Department of Civil Engineering, Indian Institute of Technology Palakkad, Palakkad, India

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Abstract

Deep soil mixing (DSM) columns are widely used to enhance the mechanical performance of very soft clays that exhibit high compressibility, low shear strength, and significant long-term settlement. However, limited studies have investigated the consolidation behaviour of soft clays improved with alkali-activated material (AAM) based DSM columns, even though AAM is a novel and sustainable alternative to conventional binders. This study presents a numerical investigation of the consolidation behaviour of organic and inorganic soft clays stabilised with AAM-DSM columns, considering a unit cell. Finite element analyses were carried out to evaluate the dissipation of excess pore pressure, time-dependent settlement, and secondary consolidation (creep) characteristics of the improved ground. The soft clay was modelled as an elastic-viscoplastic material to capture time-dependent deformation, while the DSM column was modelled as a linear elastic perfectly plastic material, using material properties obtained from laboratory investigation. A parametric study was conducted to investigate the effect of area replacement ratio, column stiffness, and column length on the consolidation responses. Additionally, the field performance of the improved ground was evaluated through numerical analysis of an embankment supported on AAM-DSM column-stabilised ground. Overall, the study highlights the potential of AAM-DSM columns as an effective method to improve the consolidation behaviour of soft organic and inorganic clays.