(1) The excavation area is large and irregularly polygonal. The natural foundation shallow foundation is only 2.6m away from the outer edge of the retaining structure at its closest point. Meanwhile, the long sides of some buildings are parallel to the foundation pit, making them highly sensitive to deformation and settlement caused by excavation, and prone to cracks and other adverse conditions.

　　(2) The underground structure construction is close to residential areas and protected buildings, with the closest distance less than 3m. The site is relatively narrow, and the available space is limited.

　　(3) The schedule is tight, requiring completion of construction below ±0.00 within 4 months.

　　(4) Obstacle clearance is highly difficult, with undisassembled old house foundations, abandoned civil air defense basements, and other unidentified underground obstacles.