This study uses the finite element software Midas GTS NX (2019), combined with actual engineering projects, to establish numerical models and analyze the impact of different support types (pile-anchor support and double-row pile support) on the excavation of foundation pits near metro station tunnels. The results indicate that under both support methods, the vertical displacement of the tunnel is the greatest at the interface between the station and the tunnel, with greater vertical displacement occurring under double-row pile support. Under pile-anchor support, the horizontal displacement of the tunnel reaches its maximum value during the sixth excavation stage, while under double-row pile support, the horizontal displacement increases steadily, and the overall displacement is small. The horizontal displacement under pile-anchor support is significantly greater than that under double-row pile support. For the station, the maximum vertical displacement under pile-anchor support is smaller than that under double-row pile support. The horizontal displacement under pile-anchor support exhibits a linear change, while under double-row pile support, the displacement continuously increases from the end of the foundation pit farther from the excavation to the end closer to it. The model tests are consistent with the numerical simulation results, verifying the correctness of the numerical simulation. This study can provide references for relevant engineering projects to ensure the safety and stability of metro structures.

With the continuous development of cities, underground space has become increasingly crowded, making the efficient and safe utilization of underground space an urgent issue to address. At present, research on foundation pit construction adjacent to existing subway structures mainly focuses on the impact of pit excavation on tunnels. While these studies have established a basic understanding of how pit excavation affects tunnels, research on adjacent subway stations and tunnels is nearly nonexistent—especially regarding the impact of the coupling effect between stations and tunnels during the excavation process. Additionally, most studies are conducted in soft soil areas, with no research yet on the impact in loess areas. To study the impact of foundation pit construction on subway tunnels and stations and reveal their coupling mechanism, model tests and numerical simulations were conducted based on actual engineering conditions. The model box had dimensions of 1.5 m in length, 1 m in width, and 1.2 m in height, while numerical simulations adopted the same dimensions as the actual project. Two different support structures—pile-anchor support and double-row pile support—were used for separate research and comparative analysis. The results show that with the increase in excavation depth, the foundation pit unloading effect becomes increasingly obvious. The pressure borne by both support structures increases, and the disturbance to the subway structure also becomes more significant. The maximum disturbance of tunnel earth pressure under the double-row pile support is 7.92 kPa, which is 224% higher than that under the pile-anchor support. The impacts on the subway tunnel and station under the double-row pile support are significantly greater than those under the pile-anchor support. Additionally, affected by the station, the locations of maximum tunnel deformation are not at the positions corresponding to the center of the foundation pit, but offset 10 m away from the station. Both the station and the tunnel exhibit a certain degree of uplift deformation, and the tunnel has significant convergence deformation in the horizontal direction. The maximum disturbance of the bending moment under the double-row pile support is 101.87 N·m, which is 19.8% higher than that under the pile-anchor support. This study reveals the coupling mechanism of the impact of adjacent foundation pit excavation on subway structures (including subway stations and tunnels) and presents the corresponding causes and phenomena, and it is of great significance for the development of related projects in loess areas and the protection of subway structures.