Deformation Characteristics and Configuration Selection of Large-Diameter Concrete-Core Stiffened Deep Cement Mixing Retaining Walls with Different Composite Configurations in Soft Ground

Concrete-core stiffened deep cement mixing (SDCM) retaining walls provide effective lateral support, making them particularly suitable for deep excavations in coastal areas with poor geological conditions. These retaining walls can be constructed in various composite configurations; however, the retaining performance of different configurations in soft ground has not yet been systematically investigated. In this study, three-dimensional numerical models were established for three typical configurations, namely the I-shaped, extended I-shaped, and three-row composite configurations. The deformation characteristics of these retaining wall configurations in soft ground excavations were investigated, and recommendations for configuration selection were proposed. The results indicate that the deformation behavior of concrete-core stiffened deep cement mixing retaining walls is similar to that of cantilever retaining structures. The capacities of the I-shaped, extended I-shaped, and three-row composite configurations to control lateral wall displacement and ground surface settlement behind the excavation increase successively. The extended I-shaped and three-row composite configurations exhibit comparable performance in mitigating excavation basal heave, and both outperform the I-shaped configuration. With 1500 mm cement-soil piles and 600 mm cores, three-row walls reduced lateral displacement and settlement by 50.0% and 59% versus I-shaped walls; both improved configurations reduced basal heave by approximately 15.4%.