The span of pile foundations beneath metro depots typically ranges from 10 to 20 m, exhibiting a notably large span. This structural characteristic results in the pile foundations bearing a more concentrated upper load, while the interstitial soil between the piles bears minimal force. Concurrently, global climate change and enhanced urban greening initiatives have led to a significant increase in rainfall in northwest China, a region traditionally characterized by arid and semi-arid conditions. This climatic shift has precipitated a continuous rise in groundwater levels. Furthermore, the extensive distribution of collapsible loess in this region exacerbates the situation, as the rising groundwater levels induce loess collapse, thereby adversely affecting the mechanical behavior of the pile foundations. In light of these factors, this study utilized the pile foundations of a metro depot in Xi'an as a prototype to conduct static load model tests under conditions of rising groundwater levels. The experimental results reveal that the load-settlement curve of the pile foundations in the absence of groundwater exhibited a steep decline with distinct three-stage characteristics, and the ultimate bearing capacity was determined to be 5 kN. When the groundwater level is situated below the loess stratum, the settlement of both the pile foundations and the foundation soil, as well as the axial force, skin friction, and pile tip force, remains relatively stable. However, when the groundwater level rises to the loess stratum, there is a significant increase in the settlement of the pile foundations and foundation soil. Negative skin friction emerges along the pile shaft, and the bearing type of the pile foundation transitions gradually from a friction pile to an end-bearing pile. The influence range of the pile foundation on the settlement of the foundation soil is approximately three times the pile diameter.

To maximize the use of urban land, many cities have built buildings above metro depots. However, the low-frequency vibration caused by metro operation affects the lives of surrounding residents, which seriously restricts the further development of over-track buildings. To study this problem, Firstly, the vibration of the metro depot and surrounding sensitive areas are tested on a large actual metro depot in Southwest China, and the rail, sleeper/support column, bearing column, and cover plate are mainly tested. Then, considering nonlinear factors such as mechanical properties of building materials, soil layering characteristics, and artificial viscoelastic boundary, the numerical coupled model of the train-track-depot-building is established, and the simulation data are compared with the test data to verify the accuracy of the numerical model. Finally, the impact of metro operation on the over-track buildings is evaluated. Results show that for the over-track buildings concerned in this paper, the floor vibration near the rail is the strongest, the main vibration frequency of the office building is concentrated in 10-20 Hz, and the maximum Z vibration level (VLzmax) of the office building is 52.02 dB. The main vibration frequency of the residential building is similar to that of the office building, and the superposition of floor vibration energy causes the vibration of the mid-span point to be larger than the vibration of the corner point and the side wall point. The vibration wave of lower floors mainly propagates through the bearing column, and the vibration of the parking garage is larger than other buildings. The research results can provide a reference for the vibration control and design of over-track buildings above the metro depot.