地铁车站基坑分步开挖空间特征的实测及数值分析

In-situ Measurement and Numerical Analysis of Spatial Characteristics of a Metro Station Pit with Staged Excavatio

狭长型地铁深基坑不同开挖方式对围护结构变形和内力的分布存在空间影响。以某地铁车站深基坑工程为例,进行现场地表沉降、地连墙水平位移和内支撑轴力的实测与分析。然后通过数值模拟方法,模拟了整体分层开挖与分块、分层开挖两种开挖方式,对地表沉降、地连墙水平位移和内支撑内力3项指标在狭长基坑上的分布特征进行了数值模拟研究,验证了数值模拟方法的可行性。结果发现:狭长基坑支护结构的变形和内力在纵、横断面上均具有较明显的空间分布不均匀特征,地表沉降、水平位移总是中部大而两端小,在标准段和扩大段交界处,支撑轴力总是最大。为狭长车站基坑的设计和施工提供理论参考。

Different excavation methods for long and narrow deep foundation pits have different spatial effects on the deformation and internal support axial force distributions of retaining structures.In this paper,three insitu parameters including surface subsidence,horizontal displacements of diaphragm wall and axial forces of internal support of a metro station construction with long and narrow deep foundation pit were measured and analyzed.Then numerical simulations of the foundation pits with two excavation methods,layered excavation method and zoned excavation method were performed.Those three parameters were also derived and compared with the in-situ measurement to verify the feasibility of the numerical simulation.The results show that the deformation and the internal support axial forces of long and narrow deep foundation pits have obvious characteristics of uneven spatial distribution in the longitudinal and cross sections.The surface settlement and horizontal displacement are always large in the middle and small at both ends.At the junction of the standard section and the enlarged section,the supporting axial force is always the largest.The conclusions above can provide theoretical reference for the design and construction of long and narrow deep foundation pits.