软黏土地层盾构开挖扰动及工后沉降数值模拟研究

Numerical simulation of disturbance characteristics and post-construction settlement caused by shield excavation in soft clay

摘要: 软黏土地层中盾构开挖必然引起地层的扰动,这种扰动所引起的地层变形以及因此产生的隧道成型之后地层的持续性变形是一直以来工程研究界极为关注的问题。利用大型有限差分程序FLAC^3D对盾构在软黏土地层中的开挖施工过程进行了精确模拟,得到超孔隙水压力在隧道形成后相当长时期内消散所引发的地层固结变形是隧道地层变形的一大因素,固结沉降占总沉降的15%左右,土体固结引起的沉降影响范围约是传统不排水分析方法的1.4倍。

Abstract: Shield tunneling in soft clay will inevitably lead to the disturbance of soil strata. The deformation caused by this disturbance and the resulting persistent deformation have been the research focus. The finite difference program FLAC^3Dis empbyed to accurately simulate the excavation process in soft soils. The consolidation deformation caused by the excess pore water pressure dissipation in the tunnel after a considerable period of formation of tunnel stratum is a major factor. The consolidation settlement is about 15% of the total settlement. The scope of soil subsidence induced by the consolidation is 1.4 times that by traditional undrained analysis methods.