A validated damage plasticity simulation framework for comparative assessment of foundation pit support : bridging code compliance and material nonlinearity

The selection of a preferred‌ foundation pit support design involves a rigorous comparative analysis of alternatives against specific performance metrics. When advanced designs incorporate material behaviors not codified in standard specifications, numerical simulation becomes indispensable for capturing the associated performance data. This study establishes a performance evaluation framework predicated on numerical simulations that integrate specialized constitutive models while complying with fundamental design codes. Leveraging a damage plasticity model for accurate material representation, the methodology is demonstrated through a case study of soil-mixing wall support schemes. Six distinct configurations, comprising variations in pile diameter and the spatial layout of embedded H-piles, are assessed using a multi-indicator framework, including shallow soil plastic strain, wall plastic damage, steel displacement, deflection curvature, and ground surface settlement. These indicators, often inaccessible via conventional analytical methods, are quantified through numerical analysis. A systematic comparison of the results facilitates the identification of a ‌preferred‌ design that reconciles engineering economy with safety constraints. The efficacy of the proposed simulation-based comparative assessment approach is further quantitatively consistent with subsequent construction monitoring data. It is noted that the total stress method is adopted throughout the analysis, wherein groundwater effects, including phreatic water, micro-pressurized water, and dewatering, are incorporated implicitly via adjusted soil unit weights rather than explicit pore pressure calculations. This treatment is justified by the relatively short construction duration compared to the consolidation time scale of the soft clay deposits, rendering undrained conditions a reasonable approximation for the serviceability-oriented performance assessment presented herein.