Abstract: For the deformation-control challenges of deep excavations in the soft-soil regions of Wuhan, this study examines a residential project in Hongshan District as a case background. To quantify how passive-zone reinforcement parameters influence support deformation, PLAXIS finite-element software was employed. The Mohr-Coulomb and Hardening Soil constitutive models were used to represent the mechanical behavior of the reinforced soil mass and the surrounding soft soil. Through parametric analysis, the study systematically investigates how reinforcement width (2~14 m), height (2~12 m), and cross-sectional configuration (horizontal and vertical rectangles, as well as stepped forms at the top or bottom) regulate the lateral displacement of a double-row pile support system. Results show that increasing reinforcement width significantly suppresses pile lateral movement, with the displacement-reduction effect stabilizing once the width reaches approximately 8 m. Considering both control efficiency and economic performance, 8 m is identified as the optimal reinforcement width for this project. Reinforcement height performs best within the 6~8 m range; beyond 8 m, improvements diminish because deeper soil layers possess better inherent properties. Regarding reinforcement configuration, vertical rectangular sections outperform horizontal ones for the same reinforcement volume, stepped configurations are more economical than simple rectangles, and bottom-stepped reinforcement provides the most effective control. A combined reinforcement scheme—bottom-stepped configuration, 8.65 m width, and 6 m height—is proposed, which limits the maximum lateral displacement of the support piles within code-specified limits and satisfies overall deformation-control requirements. The findings offer quantitative guidance for passive-zone reinforcement design in deep excavations within similar soft-soil environments.

Key words: Deep Excavation Support, Passive Zone Reinforcement, DoubleRow Piles, Deformation Control, Soft Soil Area