The study of pile foundation displacement caused by adjacent excavation of underground super large space

Abstract

It is vital to control the deformation of adjacent structures and displacement of ground caused by the excavation of underground super large space.Based on a span line adjacent to Liao gongzhuang Station which is a super large space excavation engineering in the west extension project of Beijing subway line 6, this paper proposed some treatment measures to ensure the safety of pile foundation of the bridge during the construction of the station.Meanwhile the deformation change rules of pile foundation were obtained using FLAC3D numerical simulation software, and the results were compared with field measured values.It can be concluded that:the construction of supporting arch affects on the deformation of pile foundation, and the pile foundation deforms more significantly with the shorter of distance between pile foundation and the station.The maximum lateral displacement of the top of pile foundation is about 2.2 times larger than maximum vertical displacement.Stiffness of the pile cap has significant influence on the lateral and vertical displacement of the pile foundation, the largest vertical displacement of piles with a cap is 7/10 of that without a cap when the ratio between depth (H)of station botton plate and the distance between piles and the station (L) is 3, while the largest lateral displacement is 1/3 of that without cap.With increasing stiffness of the cap, the difference of settlements between piles could reduce effectively, and the settlement distribution of pile are more uniform.

Keywords

• super large section
• underground space
• pile cap stiffness
• pile group displacement
• numerical calculation