路堤高度和加筋对软土地基累积塑性变形的影响

Influence of Embankment Thickness and Reinforcement on Cumulative Plastic Deformation of Soft Soil Foundation

摘要:

运用有限单元法对交通荷载作用下软土地基进行隐式动力分析,基于累积塑性变形的计算和影响因素分析,研究路堤高度对交通荷载引起的软土地基累积塑性变形的影响,在此基础上,从地基中动偏应力分布的角度,揭示了土工格栅加筋对于减小交通荷载引起的软土地基累积塑性变形的意义和机理.分析结果表明:当路堤高度1 m左右时,在交通荷载作用下,地基中会产生显著的累积塑性变形;随着路堤高度的增加,地基中由交通荷载引起的累积塑性变形迅速减小.对于受交通荷载影响显著的软土地基,土工格栅加筋改善地基表面的压应力分布,减小传递到地基表面的剪应力,加筋后地基土累积塑性变形明显减小,主要是由于加筋减小了地基土的上部由交通荷载引起的动偏应力.

Abstract:

Soft soil foundation under traffic loading was modelled by implicit dynamic finite element method (FEM).Based on numerical model,calculation and influential factor analysis of cumulative plastic deformation,a study was made of the influence of the thickness of embankment on cumulative plastic deformation induced by traffic loading.Then,from the standpoint of distribution of dynamic deviator stress of soil foundation underneath the center of loading area,an investigation was made into the meaning and mechanism that reinforcement could decrease cumulative plastic deformation of soil foundation.Analysis result shows that the cumulative plastic deformation of soil foundation with about 1 m thickness embankment develops rapidly under traffic loading.The cumulative plastic deformation decreases distinctly with the increasing of the thickness of embankment.As for soft soil foundation which is influenced significantly by traffic loading,geogrid reinforcement can improve vertical stress distribution,and decrease shear stress on the surface of soil foundation.The main reason of the decrease of cumulative plastic deformation of reinforced soil foundation is that reinforcement can diminish deviator stress on the upper part of it induced by traffic loading.