Pareto-optimal performance-based robust design of SDCM column-reinforced embankments: A parametric optimization study

Abstract

This study introduces a multi-objective optimization framework that integrates response surface methodology (RSM) with Pareto front analysis for the design of embankments supported by stiffened deep cement mixing (SDCM) columns, compared to conventional deep cement mixing (DCM) columns. The framework addresses trade-offs among column construction costs, ultimate limit states, and serviceability criteria in soft clay ground improvement. Key design parameters, column diameter, length, spacing, strength, and core pile characteristics, are examined through parametric analysis. Results show that SDCM columns provide column construction cost savings of approximately 48–55 % under stringent serviceability constraints. Column spacing and dimensions have the greatest influence on performance, while core pile length plays a critical role in overall performance. For a target global factor of safety of 1.5, optimal SDCM configurations can reduce column construction costs by up to 73 % compared to a documented DCM-supported highway embankment. These cost comparisons are specific to Bangkok clay conditions and exclude core pile installation costs; actual savings may differ based on site-specific soil properties and construction practices. The use of Pareto front solutions allows engineers to efficiently assess trade-offs between cost and safety without relying on trial-and-error methods. The proposed framework is especially useful during preliminary design phases when multiple design alternatives must be evaluated. It is also adaptable to other soil conditions by updating the finite element modeling and RSM parameters. Overall, the study provides a systematic and flexible approach for cost-effective ground improvement, particularly relevant to highway and railway embankments where both safety and economic efficiency are essential.