武汉地铁深基坑围护结构钢支撑轴力研究

The Study on Axial Force of Steel Shotcrete Protective Structures on Deep Foundation Pit in Wuhan Subway

钢支撑的轴力变化是深基坑监测的重要内容,它是验证深基坑设计合理性,保证安全施工的重要依据。武汉地铁名都站深基坑因开挖深度大、周边高层建筑物多、管线密布等原因,钢支撑的支护作用对于维持该基坑的稳定性尤为重要,所以监测和研究钢支撑轴力的变化,对于分析基坑稳定性具有十分重要的意义。以名都站深基坑钢支撑监测数据为基础,分析深基坑开挖过程中钢支撑轴力的变化情况。同时,采用莫尔-库仑本构模型,建立了各道钢支撑在不同开挖阶段的轴力分布模拟云图,并进行有限元分析,得到了深基坑施工过程中的钢支撑轴力变化规律。此外,还对各横撑与斜撑的轴力模拟计算最大值与监测最大值进行了对比分析,得出模拟值与监测值较为接近,为后续武汉地铁深基坑的设计和施工总结了值得借鉴的经验。

The axial force alteration of steel shotcrete is a very important part in deep foundation pit monitoring, which is used to check the rationality of pit design and to guarantee the construction security. Because of the deep ex cavation, a large number of buildings surrounded and density of pipelines in deep foundation pit, the steel shotcrete support is very important to the stability of the pit. Therefore, the monitoring and study of the axial force alteration of steel shotcrete is very significant to analysis of the pit stability. This paper, based on the monitoring data of steel shot crete in the foundation pit of Mingdu Station of Wuhan Subway, analyzed the axial force alteration during excavation. Meanwhile, the MohrCoulomb constitutive model was adopted to build mimic diagrams of the axial force in different excavation stages and the finite elements analysis was done, and the rules of the axial force alteration in deep pit construction was obtained. Besides, the comparative analysis was conducted between simulation maximum and monitored maximum of the axial force in flying shore and diagonal bracing. It can be concluded ： the simulation value is close to the monitoring value. It can provide useful experience for the design of deep foundation pits in Wuhan Subway.