狭长型地铁基坑的空间效应定量化研究

Quantitative Study on Spatial Effect of Elongated Metro Foundation Pit

为定量化分析狭长型地铁基坑的空间效应对支护结构变形的影响,在验证基坑数值模型有效的基础上,通过有限元数值模拟方法研究了不同长宽比和深宽比基坑开挖后支护结构的变形。结果表明:随着基坑长宽比的增大,长边支护结构的最大水平位移变化显著,且明显大于短边的最大水平位移,浅坑的(H/B<1,H为挖深、B为基坑宽度)长短边最大水平位移比达到8,深坑(H/B>1)的位移比在3左右;基坑长宽比为1<L/B<3(L为基坑长度)时,基坑长边的水平位移受空间效应影响变大;工程设计中,长宽比为3左右的浅坑和长宽比为2左右的深坑适合采用二维剖面设计方法。

In order to quantitatively analyze the influence of spatial effect of elongated metro foundation pit on the deformation of supporting structure,on the basis of verifying the effectiveness of the numerical model of foundation pit,the deformation of supporting structure after excavation of foundation pit with different length width ratio and depth width ratio were used to investigate by finite element numerical simulation method.The results show that the maximum horizontal displacement of the long side retaining structure changes significantly and is significantly greater than the maximum horizontal displacement of the short side.It is concluded that the maximum horizontal displacement ratio of shallow pit(H/B<1,H is the depth of excavation,B is the width of foundation pit)is 8,and that of deep pit(H/B>1)is about 3.When the length width ratio of foundation pit is 1<L/B<3(L is the length of foundation pit),the horizontal displacement of the long side of the foundation pit is affected by the spatial effect.In engineering design,the shallow pit with the aspect ratio of about 3 and the deep pit with the aspect ratio of about 2 are suitable to adopt the two-dimensional profile design method.