Spatial effect of surface settlement during excavation and dewatering under non-equilibrium loading

In order to study the spatial effect characteristics of surface settlement at different characteristic profiles during dewatering excavation of subway pits under non-equilibrium loading, a subway station pit project in Nanchang is taken as the background, and a three-dimensional numerical model is established with PLAXIS 3D for simulation. The simulated values demonstrate a strong correlation with the measured values, which verifies the efficacy of numerical simulation. By altering the magnitude of the non-equilibrium loading and dewatering excavation conditions, the impact of different loadings on the settlement outside the pit under step-by-step and one-time dewatering excavation conditions was studied. Additionally, the spatial effect characteristics of settlement at various characteristic profiles were analyzed. The spatial effects of surface settlement outside the pit under different non-equilibrium loading and dewatering schemes were discussed. The findings indicate that due to the influence of non-equilibrium loading, the settlement on the side close to the loading is greater than that on the side far from the loading. In comparison with the one-time dewatering excavation condition, the settlement values at each characteristic profile outside the pit are reduced under the step-by-step dewatering excavation condition. Under both dewatering excavation conditions, the non-equilibrium loading weakens the spatial effect of settlement on the side near the loading. Conversely, the effect on the spatial effect of the settlement on the side far from the loading is the opposite, which is related to the combined effect of non-equilibrium loading and segmented excavation.