Abstract: This paper presents a case history of the safety control of a deep excavation of a subway station in the saturated gravel stratum. Based to the pre-reinforcement ideas for the entire process of the new structures, the rock and soil mass between the new structures and the existing structures, the existing structures involved in the adjacent construction and the targeted reinforcement measures are adopted to minimize the influence of the adjacent deep excavation construction on the surrounding environment: 1) The new subway foundation excavation supporting system adopts the “diaphragm wall + internal support” retaining structure system and the groundwater control measures of sealing the bottom with the Sleeve Valve Pipe Grouting Method; 2) The municipal viaduct pile foundation near the subway station is pre-extended, the grouting pipe is reserved around the pile cap and the jet grouting isolation pile is applied between the piles and the cut and cover foundation; 3) bored cast-in-place concrete piles are installed between the subway excavated area and the adjacent area. The results of deep excavation supporting system show that the method used, and the pre-reinforced measures are effective and achieve a good safety control effect. The project can provide a reference for the similar projects of the future deep excavation construction.

Key words: Approaching Construction, Cut and Cover Construction, Subway, Safety Control