被动加固区参数变异性对软土深基坑变形行为的影响

被动区加固是控制软土深基坑变形的有效措施之一，但加固区土体力学参数往往表现出极强的空间变异性，势必会给软土深基坑整体变形行为带来一定的不确定性。鉴于此，通过FLAC^3D软件建立了基坑开挖三维动态模型，基于K-L法生成了水泥土参数随机场，并进行了确定性与不确定性数值分析。重点比较了两种分析方法中地连墙最大水平位移与地表最大沉降的结果差距，统计了不确定性分析中变形指标的分布趋势，探讨了水泥土参数变异性强弱对不同厚度被动加固区加固效果的影响。结果表明：考虑水泥土材料参数空间变异性时，被动区加固存在临界加固厚度；被动加固区参数变异性的强弱对软土深基坑整体变形行为的影响有限，在评估软土深基坑的变形程度时，不必对加固区参数的空间变异性作特殊考虑。

Effect of spatial variability of engineering properties on holistic performance of passive zone improvement for deep excavation in soft soil

Passive zone improvement is one of the most effective measures to control the deformation of deep excavation in soft soil. However, the soil mechanical parameters of improvement zone often show strong spatial variability, leading to the uncertainty of overall deformation behavior of deep excavation. Therefore, a three-dimensional model simulating the process of excavation is built by FLAC^3D software, random field models for cement-soil parameters are established based on K-L transformation, then deterministic and probabilistic analyses are conducted. The maximum horizontal displacement of diagram wall and the maximum ground surface settlement in both deterministic and probabilistic analyses are compared. Distribution patterns for the two deformation indicators are fitted, and the influence of coefficient of variation in cement-soil properties on the effect for different passive zone improvement thicknesses is also investigated. The results indicate that:a critical improvement thickness exists while considering the spatial variability of cement-soil; the spatial variability of cement-soil has limited influence on the overall deformation behavior of deep excavation and needs no special consideration in holistic performance evaluation.