Design of Enclosure for Subway Station Foundation Pit in Southward Extension Line of Chengdu Metro Line One

This paper summarizes the design of open-cut subway station in Chengdu Metro line one. The station is built by cut and cover method and divided into three special parts with four different cross-sections used for main line and transfer track. Such retaining techniques as bored piles, steel pipe struts, soil nails, rock-bolts, steel-meshes, shotcrete and anchored steel cables are comprehensively used to maintain the stability of foundation pit. The anti-buoyancy coefficient of the open cut station is also derived and attains the requirement of safety and stability for the foundation pit after the utilization of these enclosure measures. The application of the design and construction technique for the subway station may provide guidance for the building of analogous subway station under similar geological and hydrogeological conditions in Chengdu.