关键词: 非对称围护结构, 超载, 基坑两侧, 土体侧向应力, 倾斜度, 挠度

Abstract: In this paper, the influence of surcharge on the stress and deformation of retaining structures with different embedded lengths at each side is investigated through numerical analysis and field measurement relying on a foundation pit project in Xiamen. Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) software is used to establish the typical section analysis model of the deep excavation. Soil behaviors are modeled by a constitutive that considers degradation of stiffness with shear strain. Excavations with different embedding depths and surcharges are simulated. Structure deformation, as well as adjacent soil stress distribution, is analyzed in association with field measurement. It is found that surcharge not only increases the stress and deformation of the retaining structure near the surcharge, but also forces the top of other retaining structure to move away from deep excavation. This further results in the passive earth pressure outside the pit and increases the deflection of the retaining structure on both sides. When the embedded depth of that retaining structure is insufficient, the surcharge further increases the inclination of retaining structure, which may cause significant kicking deformation. However, the deformation and tilt of the far-surcharge side retaining structure can be limited by increasing the embedded depth of retaining structure near the surcharge. When the distance between the surcharge and the foundation pit is greater than half of excavation depth, the effect of surcharge on the side overload of far-side can be ignored. The numerical results are consistent with the field measurement and can provide reference for related projects.

Key words: asymmetric retaining structure, surcharge, both sides of excavation, lateral stress of soil, inclination, deflection