地铁深基坑围护结构安全监测与数值模拟分析

为了研究地铁基坑开挖过程中围护结构的安全性,以广东省某地铁车站为工程实例.介绍了基坑开挖方法,利用MIDAS/GTS对基坑开挖过程进行了模拟,并与不同工况下的桩身位移变化和支护轴力监测进行了比较.结果表明,围护桩顶和桩底位移较小,围护桩的最大位移位置随开挖深度的变化而移动,最大位移位置逐渐下降,最大位移接近第三梁内支撑的顶部.模拟轴力结果显示:标准段距离盾构井约50 m内冠梁呈受拉状态.模拟和现场轴力监测数据显示:第一道标准段内支撑轴力大于盾构井内支撑轴力,随着开挖深度的增加,轴力最大值内支撑位置也在下移,最终出现在盾构井第三道内支撑上.

Safety Monitoring and Numerical Simulation Analysis of Retaining Structure for Deep Foundation Pit of Subway

In order to study the safety of enclosure structure in the process of subway foundation pit excavation,a subway station in Guangdong province is taken as an engineering example.The excavation method of foundation pit is introduced,and the excavation process of foundation pit is simulated by Midas/GTS,and the displacement changes of pile body and the monitoring of support axis force are compared with the different working conditions.The results show that the retaining pile top and the retaining pile bottom is small and the maximum displacement position of the retaining pile position moves along with the depth of excavation,the maximum displacement position gradually moves down,and the maximum displacement is shown close to the top of the third beam of internal support.The simulated axial force results show that the crown beam of the standard section is in tension about 50 m range from the shield shaft.The simulation and in-situ axial force monitoring data show that the support axis force in the first standard section is greater than that in the shield shaft.With the increase of the excavation depth,the position of the axial force of the maximum internal support is also moving down,and finally appears on the third internal support of the shield shaft.