Abstract: In the process of installing steel brace in foundation pit with the gantry crane and the excavator, there always exists the problems of nonstandard construction, high construction risk, low operation efficiency, and long material operation cycle. Arming at these problems, a novel technology is proposed based the project of Liuyanjing metro station of Nanchang metro line 3 constructed by semicover excavation method. Through researching the supporting embedded parts of suspended crane and the track walking system, the steel brace mounting technology by combining a gantry crane on the ground and a hang crane installed below the cover plate is developed and successfully employed. The engineering practice demonstrates that: (1) The standardization level of construction in worksite is improved by the standard operation processes where the steel braces are installed by the cooperation of a hanging carne and a gantry crane; (2) Compared with the traditional construction method, the daily production capacity of the steel support is increased from 3 to 5 after the proposed method is employed; and (3) After adopting the new technology, the manual link is reduced, the labor intensity is greatly reduced, and the safety risk in the traditional construction process is eliminated.

Key words: semicover excavated metro station, deep foundation pit, steel brace, crane installed below cover plat