Estimation of Excavation Wall Displacements Using the Optimized Zoning Method for Soil Deformation Modulus in 2D FEM

Accurate prediction of retaining wall displacements is essential to ensure safety and protect adjacent structures in large-scale urban excavations. However, inherent uncertainties in soil parameters often limit prediction accuracy, and cumulative deviations may result in significant overestimation or underestimation of wall displacements at the final excavation stage. Although observational construction methods and inverse analysis approaches have been proposed to sequentially update parameters using early-stage monitoring data, these studies have primarily focused on numerical values, such as deformation modulus. However, limited attention has been paid to the spatial extent over which these parameters are assigned. This study introduces a method for optimizing the zoning width of the soil deformation modulus by incorporating monitoring data from the initial excavation stages into finite element analysis. A Mohr–Coulomb constitutive model was adopted, and the maximum wall displacement was used as the primary evaluation index. The optimal zoning width was defined as the condition that minimized the difference between measured and simulated displacements. The results demonstrate that the proposed optimization approach improves the predictive accuracy of wall displacements in later excavation stages. The proposed method was validated using a single excavation case; therefore, further verification using multiple case histories is required to confirm its broader applicability.