Abstract: Deep excavation supporting design and construction in the urban areas might be frequently encountered many challenges, such as, underground utilities and structures; narrow sites; potential impact to the adjacent buildings and structures. This paper presents a case history of deep excavation design and construction in the confined spaces: All China Woman Federation office building expansion project. The excavation supporting design utilizes the existing structures to serves as the supporting structure. The existing reinforced basement wall and the new cast in place piles are combined in the design. The performance of the new piles and the existing concrete wall are numerically simulated by using MIDAS GTS NX. The numerical analysis and the construction monitoring results indicate that, ⑴ the combined supporting structure had very small lateral deflections and these lateral deflections are far less than the allowable values in the design codes. ⑵ the finite element analysis results were consistent with the monitored values. The numerical analysis can be used to predict the performance of the entire excavation and to predict the behavior of a concerned structure element.

Key words: Building Expansion, Deep Excavation Support, Finite Element Analysis, Combined Supporting