Parametric study for the sustainable optimisation of T-shaped deep cement mixing columns

The sustainable application of T-shaped deep cement mixing (DCM) columns necessitates optimisation to improve cost efficiency while maintaining structural performance. This study presented a novel column called a varied strength T-shaped DCM column. A parametric optimisation is carried out by integrating numerical modelling with performance-based assessment, considering three cases of T-shaped DCM columns, namely variations in depth-based strength and localised strength variations in the core of the head and body sections. Results show that settlement is minimally affected by lower column strength, with load-bearing capacity mainly governed by the head and upper three-fifths of the column body. Increasing body strength with depth yields a non-linear increase in bearing capacity, while deformation remains concentrated in the head and its transition area with the body. The optimised construction costs for the three columns are approximately 0.847, 0.970, and 0.933 times the normalised cost, respectively. Variation in strength within the core of the column body appears to have minimal effect on bearing capacity characteristics. However, the T-shaped DCM column with depth-based strength variation exhibits better overall performance and notably lower construction costs, surpassing other configurations. The findings will support the sustainable development of T-shaped columns by integrating cost efficiency with long-term operational stability and reduced environmental impact.