Experimental investigation on the deformation characteristics of locking-steel- pipe (LSP) pile retaining structure during excavation in sand

Abstract

Locking-steel-pipe (LSP) piles connect with adjacent joints to form a pile row enclosure structure. Due to the advantages of quick construction, efficiency in installation, and recycle utilization, the connected LSP piles are frequently used as retaining structure in deep excavation. However, systematic studies of the deformation mechanism of the LSP pile retaining structure are rarely reported, and it still lack of experimental evidence to optimize the design. In this study, a braced supported excavation experimental model test in sand was designed and conducted to investigate the deformation characteristics of LSP pile retaining structure. Three dimensional (3D) printing technique was creatively applied to manufacture LSP model piles. The experimental results show that, a “S” shaped distribution of bending moments is observed along pile shaft when excavation is executed; the deflection of pile shaft develops deep-seated movements toward the excavation side as excavation went deeper, resulting in a “bowl” ground settlement. With the deflection of LSP piles, a rotating trend was occurred between pairs of locking joint, and the severe open deformation of locking joint arose on excavation side. There was a gradual reduction in earth pressure behind the LSP pile retaining wall with excavation depth. The earth pressure between two struts level had no obvious changing, owing to the supported effect of inner struts.