Abstract: During the construction of urban underground space engineering, due to the contradiction between land use and construction duration, two or even more deep excavations will be constructed concurrently, resulting in the different impact on the adjacent environment. The design of deep excavation support structure will face the selection of the same pit excavation and sub pit excavation plans. Different excavation plans have an important impact on the safety, economy and surrounding environment of excavation engineering. This paper presents a case history of the deep excavation of a regulation and storage tank and local treatment station in Jiujiang City, Jiangxi Province. The stress characteristics, safety and economy of the excavation supporting structure are evaluated. The different design plans for the excavation supporting structures for the two adjacent projects are compared and the design of the construction of the same excavation and separate excavation of the other pit are selected.

Key words: Adjacent Deep Excavations, Support System, Design Optimization, Construction of Separate Excavations, Construction Within One Excavations