Objective In order to reveal the influence of foundation pit group entire construction process on the deformation characteristics of adjacent existing station and ancillary structures, it is necessary to study the coupling effects, additional stress superposition, and structural responses at different construction stages. Accordingly, the evolution of the stress field during foundation pit construction and its relationship with the deformation of existing structures are further quantitatively analyzed.

Method Based on a T-shaped transfer station project of Zhengzhou Metro Line 12, numerical simulation methods are employed to analyze the impact of the entire construction process of the foundation pit group on the deformation characteristics of the existing station structures and ancillary structures. The research findings are applied to the construction of the above-mentioned metro station, and the accuracy of the numerical simulation results is verified through on-site monitoring data.

Result & Conclusion  After the excavation and unloading of the foundation pit group, the coupling effects and the superposition of additional stresses lead to non-uniform settlement of the adjacent metro station and ancillary structures under the action of multiple and multi-direction additional stresses, resulting in an S-shaped horizontal distortion and a parabolic vertical deformation of the track. Different construction conditions of the foundation pit group generate different superimposed stress fields, leading to varying mechanical responses in the existing adjacent metro station and ancillary structures. Construction from near to far with interval excavation creates a shielding effect, effectively reducing the deformation of the existing adjacent structures. The overall deformation is more significantly influenced by the larger-scale foundation pits within the group.