Study on Excavation Response of Metro Station Foundation Pit in Water-Bearing Strata Adjacent to Tall Buildings

The presence of adjacent tall buildings significantly affects the mechanical response of water-rich strata during metro station excavations. This study focuses on the deep construction pit excavation project of the Houhu Fourth Road Metro Station on Wuhan Metro Line 12. The deformation of the retaining structure and the surface settlement behind the wall obtained from field monitoring data are analyzed. Finite difference numerical simulations are conducted to investigate the responses of water-bearing strata adjacent to tall buildings during the excavation process of the construction pit. The numerical simulation results show that during the excavation process, the maximum deformation of the diaphragm wall is approximately 25.1 mm. It occurs at the position where the wall is buried 28 m deep. The maximum value of ground settlement is approximately 11.9 mm. Furthermore, an empirical formula for predicting the ground settlement under the influence of adjacent buildings and construction pit excavation—applicable to water-bearing sandy strata with conditions similar to those of the Houhu Fourth Road Metro Station—is proposed. The results, derived from the Houhu Fourth Road Metro Station case, demonstrate that the ground surface settlement profile in its water-bearing sandy stratum is significantly altered due to groundwater seepage and the additional loads from nearby buildings. The settlement predicted by the empirical formula shows good agreement with both measured and simulated data: the correlation coefficient (R2) between the predicted values and measured data is above 0.92.