Abstract: As a supporting structure for deep excavations, the secant pile is formed by cutting the adjacent piles, which constructs a continuous piled retaining structure with a good waterproof and seepageproof function. The internal bracing is a system that provides the support and the restraint for the strength, deformation and stability of exterior envelope. It is composed of horizontal bracing (corner bracing, opposite bracing, trusses and circular supports, etc.) or slanting bracing, column, etc. This paper presents a case history of a deep excavation support system in Shenzhen. Combined with the characteristics of this project, the application of secant pile bracing structure in the deep excavation under limited urban space is fully analyzed, in which not only ensures the safety of excavation bracing structure, but also ensures the deformation of the adjacent structures are within the allowable limits. The safety and the normal use of surrounding buildings are satisfactory.

Key words: Deep Excavation, Secant Pile, Internal Bracing