依托厦门某基坑工程，通过数值分析和现场测试，研究超载影响下围护结构非对称基坑的受力及变形特性.采用Fast Lagrangian Analysis of Continua in 3 Dimensions(FLAC3D)软件建立基坑典型断面分析模型，结合考虑刚度随应变衰减的土体本构，模拟分析不同嵌固深度和超载作用下的围护结构变形以及邻近土体的应力分布，并综合现场测试数据验证该理论研究的结论.研究结果表明：超载不仅增大近超载侧围护结构的受力和变形，还会引起远侧围护结构顶部出现远离基坑的位移，从而产生坑外被动土压力，增大两侧围护结构的挠度；当远超载侧围护结构的嵌固深度较小时，超载会进一步增大围护结构的倾斜，使其呈现踢脚式变形；近超载侧围护结构嵌固深度的增加对远超载侧的挠度及倾斜度有控制作用；当超载与基坑距离大于0.5倍开挖深度时，超载对于远超载侧围护的影响可以忽略.现场实测结果与理论研究结论相一致，研究成果可为相关工程提供参考.
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.
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