The objective of this study is to examine the service performance of a cantilevered enclosure during the excavation of a high slope pit under rainfall conditions. The high slope sinking plaza pit of Shenzhen Wuhe Intercity Hub Station is taken as the research object. Based on the field measurements, an analysis is conducted of the evolution of the wall top displacement of the cantilevered enclosure diaphragm wall of the high slope pit under the condition of continuous heavy rainfall. This study focuses on the ZQ-8 hazardous monitoring section. The depth of the soil body in the saturated area outside the pit was calculated, and the saturated soil and soil at the bottom of the pit outside the pit were softened using the strength reduction method. A numerical simulation analysis was conducted to study the softening of soil outside the pit. A simulation analysis was employed to investigate the impact of soil softening both within and outside the pit, as well as the reinforcement of anchor cables, on the internal force and deformation of the ground connecting wall. The results demonstrate that: In the event of soil softening within and around the pit, the maximum bending moment of the ground-connected wall reaches 1 600 kN·m, which is in close proximity to the ultimate design bending moment. Additionally, the maximum horizontal displacement of the enclosure reaches 76.0 mm; In the case of significant deformation of a cantilever-supported foundation pit with high slopes under continuous rainfall conditions, the use of prestressed anchor cables for emergency treatment is recommended, while backfill counterpressure has limited efficacy. The research findings can provide theoretical support for safe construction in the field and can also serve as a reference for other similar projects.