Abstract: In the construction of urban underground projects, especially in the central urban area, the adjacent foundation excavation projects are often encountered due to the restriction of land and construction schedule. Compared with the independent foundation deep excavation projects, the interaction of adjacent foundation excavations has an impact on the deformation of the supporting structures and the deformation of the surrounding soils. These factors will make the stress, deformation of the supporting structure and the impact of the surrounding environment more complex. The interaction between the foundation excavations cannot be ignored. This paper presents the foundation excavation of a storage tank and local treatment station in Jiujiang City, Jiangxi Province as the case history. This paper uses the numerical simulation method to study the influence of different excavation methods of the adjacent deep excavation and compares the difference and change pattern of the synchronous excavation and step-by-step excavation of the adjacent excavation from the perspectives of the soil deformation, internal force and deformation of the supporting structure, and the influence of the surrounding environment. It provides a reference for the relevant projects. The results show that: 1) the synchronous excavation has more disadvantageous in terms of the surface settlement between the adjacent excavations. The surface settlement can be reduced by about 18% if the step-by-step excavation is adopted; 2) Under different excavation methods, the maximum horizontal displacement of the supporting structure is similar, and the overall bending moment of the soldier pile is not different; 3) From the settlement of the existing pipelines, the step-by-step excavation is more unfavorable. The maximum settlement occurs after the excavation of a single deep excavation. If the synchronous excavation method is adopted, the pipeline settlement can be reduced by about 28.6%. 4) For the settlement of buildings, in the case of the synchronous excavation, the maximum settlement occurs near the storage tank. Under the step-by-step excavation, the maximum settlement occurs near the local treatment station.

Key words: Adjacent Deep Excavation, Enclosure Structure, Synchronous Excavation, Environmental Impact Analysis, Numerical Simulation