<p>The Beijing transportation hub project faces the issue of constructing large-scale open-cut underground structures in zero-distance proximity to an existing metro station. During the excavation of the new foundation pit, the existing station is prone to bearing asymmetric lateral pressures, posing a threat to its structural safety. To address this, this paper proposes a two-stage phased construction strategy. In the first stage, the foundation pit areas far from the station (Area A and Area B) are excavated, and the underground structure construction in Area A is completed. Meanwhile, a reserved earth berm is left in Area C adjacent to the station to provide necessary lateral support. In the second stage, after the structure in Area A reaches the predetermined strength, the reserved soil in Area C is excavated, and the underground structures in Area B and Area C are constructed. During this period, a horizontal internal support system is erected between the existing station and the newly built structure to maintain the structural stability of the existing station. The results from simulations and field monitoring indicate that, during the phased construction process, the horizontal displacements of the existing station and the newly constructed structure in Area A, the additional stresses in the floor slabs of the newly constructed structure, and the axial forces in the horizontal internal supports all meet the control requirements, thereby demonstrating the effectiveness of the phased construction strategy.</p>