地铁车站软土深基坑开挖变形全过程数值模拟研究

Whole Process Numerical Simulation Study of Soft Soil Deep Foundation Pit Excavation Deformation of Subway Station

软弱土层的深基坑施工会引起周边道路开裂及临近建(构)筑物沉降,如变形过大则会对周边建(构筑物产生不利影响。文章以南京地铁5号线虹桥站地铁车站为研究背景,基于有限元软件建立了地铁深基坑全过程开挖的三维数值模型,其中土体采用摩尔-库伦本构模拟其力学行为,结合特定断面对软弱土层基坑开挖施工过程的支护结构性状和基坑土体变形的情况进行分析。数值计算结果与实测对比表明:围护结构侧位移与实测比较一致,沉降值较实测偏小,分析其原因可知施工过程中的一些临时荷载,在数值模拟中并未体现,所以导致了两者的差异。因此,在实际施工中应着重控制基坑周边的地面超载,避免产生过大沉降和地表倾斜。

Deep foundation pit construction in soft soil will cause cracking of surrounding roads and settlement of adjacent structures.If the deformation is too large,it will have a negative impact on the surrounding buildings.In this paper,the subway station of Hongqiao Station of Nanjing Metro Line 5 is taken as the research background.Based on the finite element software,a three-dimensional numerical model of the whole process excavation of the deep foundation pit of the subway is established.The Mohr-Coulomb constitutive model is used to simulate the mechanical behavior of the soil.The supporting structure and the deformation of the foundation pit soil during the excavation of the soft soil foundation pit are analyzed.The comparison with the actual measurement shows that the lateral displacement is consistent with the actual measurement,and the settlement is smaller than the actual measurement.The reason may be that the temporary load in the construction process is not reflected in the numerical simulation,so the difference between the two is caused.Therefore,in the actual construction,the ground overload around the foundation pit should be controlled to avoid excessive settlement and surface tilt.