超长、超大基坑开挖对邻近地铁结构安全影响的数值模拟分析

Numerical Simulation and Analysis of Subway Structure Safety Influenced by Excavation of Super Long and Large Foundation

为了研究超长、超大基坑开挖对邻近地铁结构安全影响,以西安地铁2号线周边某基坑为工程实例,通过运用数值分析软件,结合场地的水文地质和工程地质条件,建立数值模型,进行施工过程的动态模拟,同时进行现场监测,经对比数值模拟结果及监测数据,表明运用PLAXIS软件能有效的模拟基坑开挖过程中的土体变形。同时工程采用的分段、分块开挖,中心岛顺做,周边预留土台反压、使用旋喷锚索的支护方案,对复杂条件下基坑开挖对邻近地铁结构的变形影响能起到有效的控制作用,可对类似工程的设计优化提供有益的参考及借鉴。

In order to analyze the influences of super-long and large excavation on the adjacent subway structure, this paper took the foundation pit surrounding the Xi＇an metro line 2 as an engineering example, a numerical model was developed to carry out the dynamic simulation and safety evaluation of the subway structure during the construction process. The simulation results and monitoring data show that PLAXIS software can effectively simulate the excavation of soil in the process of deformation, the piecewised excavation method which divide the whole project into small pieces and adopt the support scheme of center island method which use surrounding soil table to resistance pressure at the same time, plus use of rotary spray anchor cable, have an effective effects on the deformation of metro structure control caused by the excava- tion of foundation pit.