土体小应变条件下紧邻地铁枢纽的超深基坑变形特性数值分析

 以上海地区一紧邻地铁枢纽的超深基坑工程为分析对象，考虑土体的小应变刚度特性，建立地铁区间隧道和邻近基坑的二维有限元分析模型，探讨土体小应变条件下超深基坑的变形特性。算例分析表明，考虑土体小应变刚度特性可以显著减小超深基坑的变形，计算结果与实际情况更为吻合。对于紧邻地铁枢纽的超深基坑，开挖顺序对于基坑变形也有着显著影响，在同样的计算模型下，先开挖大基坑再开挖紧邻地铁枢纽的小基坑，可以明显地减小超深基坑的变形，这与上海地区已有的工程实践经验是一致的。所获得的结论对于紧邻地铁枢纽的深基坑工程设计与施工具有重要参考价值。

NUMERICAL ANALYSIS OF DEFORMATION OF DEEP EXCAVATION ADJACENT TO METRO CONSIDERING SMALL-STRAIN STIFFNESS OF SOIL

Based on a case of deep excavation adjacent to metro station in Shanghai City，a two-dimensional finite element model to analyze this typical problem is proposed. Small-strain stiffness of soil is considered to investigate the deformation characteristics of deep pit excavation adjacent to metro station. The calculation data show that the deflection of retaining wall is obviously reduced when the small-strain stiffness of soil is considered in numerical analysis. And it is much close to the observed results. As for the deep pit excavation adjacent to metro station，the excavation sequences have obvious influences on the deformations of retaining wall. Numerical results also show that excavating big parts of the pit foundations firstly can reduce the deformation of retaining wall effectively than that of excavating small parts in advance. The results are consistent with the practical experiences in Shanghai area. The conclusions have some instructions for the designs and constructions of similar engineering.