A novel stiffened deep soil mixing wall system for deep excavations in soft clay: 3D numerical analysis

Deep excavations in soft soils present complex geotechnical challenges, particularly in maintaining stability during the construction process. The low shear strength and high compressibility of these soils often lead to failure mechanisms that require careful analysis. This study introduces a novel Stiffened Deep Soil Mixing retaining wall system with connectors (SDSMC) for deep excavations in soft clay. Using 3D finite element analysis, the performance of the SDSMC wall was evaluated under varying steel column profile orientations, profile sizes (HEA 100, 200, and 300), and connector configurations. Results show 66% reduction in lateral displacement and 64% reduction in ground settlement compared to conventional Deep Soil Mixing walls. Superior performance was achieved when the strong axis of the HEA (H-beam European standard, series A) section was oriented perpendicular to the lateral earth pressure (X-orientation) and with larger profiles (HEA 300). Strategic connector placement, particularly with two connectors positioned at the top and bottom of the steel column, enhanced wall performance by up to 30%. The findings validate the SDSMC system as a cost-effective, robust, and sustainable alternative for urban deep excavations in soft clay conditions, further experimental validation is recommended to confirm its performance under realistic field conditions and to account for factors such as interface behavior, construction tolerances, and long-term soil-structure interaction.

Keywords:
Deep excavation; Soft soil; Stiffened Deep Soil Mixing; Connectors; Lateral displacement; Settlement