水平荷载下群桩前后土抗力分布的数值分析

Numerical Analysis on Distribution of Soil Resistance in front of and behind the Pile Group under Horizontal Load

群桩基础是土木工程中主要的基础形式之一。利用由竖直桩组成的群桩基础来承受水平荷载已经十分广泛 ,桩前桩后土抗力分布特性是水平荷载下群桩受力变形特性的一个重要组成部分 ,过去的研究主要是通过实验方法和理论分析来进行的。本文用空间 2 0节点有限元进行近域土和桩的分析 ,对远域土采用空间 1 2节点无限单元 ,在桩土接融面引入空间1 6节点接触面单元 ,从而用有限元 -接触面单元 -无限元的耦和方法将群桩和土体作为一个整体进行弹塑性分析。分析中用修正剑桥模型进行近域土体的模拟 ,对桩土接触面及远域土体进行非线性分析。分析结果表明 ,本文的分析能较好的揭示水平荷载下群桩桩前。

As one of the foundation forms, the pile group foundation composed of vertical piles is widely applied to resist horizontal loads. The characteristic of the distribution of soil resistance in front of and behind the pile group is a component of deformation performance of pile group under horizontal load. At past, its study was performed by theoretical analysis and experiments. In this paper, the spatial 20 nodes FEA was used to analyze the close field soil and piles and the spatial 12 nodes infinite element analysis was used for the far ones. At the interface between the pile and soil, the spatial 16 nodes contact area elements were introduced. Thus, the pile group and soil body was treated by the elasto plastic analysis through coupling the FEA contact area element infinite element. In the analysis, the soil body of close field is simulated with the modified Cambridge Model on the contact surface between the pile and soil and the non linear analysis for the far field soil body. The results show that this analytical method can illustrate the character of soil resistance distribution in front of and behind the pile group under horizontal load.