A Method for Characterizing Stiffness of a Support System for Excavation Design

This study proposed a method to characterize the effect of support system stiffness in excavation design based on a newly developed stiffness influence factor. Three-dimensional finite-element analyses were performed considering various excavation, support, and soil conditions. Focus was given to the effect of system stiffness in irregular excavation configuration with a re-entrant corner in different soil conditions. Wall deflection and surface settlement within the re-entrant corner zone were smaller due to the corner stiffening effect, yet deeper and wider influence zones of wall deflection and surface settlement were shown. The individual performance of the influence parameters was evaluated and introduced into a unified evaluation model, and the system stiffness influence factor was established. The proposed system stiffness influence factor was sufficiently effective in predicting wall deflection and surface settlement. Case examples showed that the proposed method is valid and effective for excavation design. The sensitivity analysis showed that the wall stiffness contributed most to the performance of the wall, which was applicable to further enhancing and optimizing excavation design.