Analysis on the Safety and Stability of Deep Excavation with a Shared Wall of an Existing Metro Station

Deep excavation projects sharing a diaphragm wall with an existing metro station are increasingly common. However, existing research has mostly focused on the deformation of the shared wall itself, with insufficient systematic analysis of key indicators such as ground settlement and axial force of internal struts. Thus, the evaluation of excavation safety and stability still needs improvement. To address this, this study takes a deep excavation project that shares a wall with an existing metro station as the background and conducts research using numerical simulation methods. In the simulation, both concrete struts and steel struts are simplified as linear elastic models, while the soil is described using the modified Mohr-Coulomb constitutive model. Relevant calculation parameters are determined according to the geotechnical investigation report and design drawings, and reasonable boundary conditions and gravity loads are applied to simulate the entire process of layered excavation and timely support. The numerical simulation results show a maximum ground settlement of 6.29 mm, a maximum axial force of internal struts of 1171.9 kN, and a maximum lateral displacement of the shared wall of 2.06 mm. Compared with field measurements, the maximum error for ground settlement is 5.12%, the maximum error for axial force of internal struts is 8.20%, and the maximum error for lateral displacement of the shared wall is 7.62%. All errors are within reasonable ranges and are below the code-specified limits. The study confirms that under reasonable support conditions, deep excavation with a shared wall can maintain overall safety and stability, and the established numerical model has good reliability, providing a reference for the design and construction of similar deep excavation projects with a shared wall.