Sensitivity Analysis of Soil Parameters Influencing Ground Settlement in Top-Down Metro Station Excavations

The present research investigates a case study employing a top-down method, while incorporating both analytical and empirical approaches for the assessment of ground deformation. The investigation focuses on the settlement results derived from numerical methods. The results obtained from the modeling and analysis indicate that the maximum settlement occurs above the top slab, with ground settlement in the top-down excavation method measured at 12.3 mm. Additionally, soil parameters were subjected to a sensitivity analysis concerning hardening behavior. The sensitivity analysis revealed that an increase in the elastic modulus has the most significant impact on reducing ground settlement. To measure the settlement of the ground surface, settlement measuring pins have been installed at the entrance of the station located in the access tunnel. The settlement data obtained from the ENW-05 pin indicates a value of 4 mm. The discrepancy between this value and the settlement derived from the numerical analysis can be attributed to variations in the loading on the station and its sides, as well as the installation of settlement pins outside the station, which are situated in the access tunnel near the central core of the station.