Abstract: Traditional pile-bracing retaining structure is featured with many disadvantages such as high cost, long construction period, and large amount of solid waste produced by the demolishing of inner retaining structure. By adopting multi-level retaining structure composed of double-row pile and single-row pile, the above mentioned problems are effectively solved, and good social and economic benefits are achieved. The deep foundation pit of Capital Land’s Gutian project in Wuhan is taken as engineering background. Furthermore, the deformation and stability of the multi-level retaining structure are studied through finite element numerical simulation. Results conclude that the safety factor of stability and failure pattern have great correlation with the spacing between the two-level retaining piles, but have almost no concern with the height of earth berm. With the increasing of spacing between the two-level retaining piles, the maximum horizontal displacement of the first and second supporting piles both decreased, while the stability of foundation pit increased. With the increasing of height of earth berm, the maximum horizontal displacement of first-level retaining decreased whereas the second-level retaining increased, and the stability of foundation pit barely changed. Finally, the ranges of spacing between the two-level retaining piles corresponding to integral destruction, relational damage and separated damage, respectively, are given for reference for foundation pit design and calculation.

Key words: deep foundation pit, double-row pile, multi-level retaining, finite element, spacing between two-level retaining piles, height of earth berm