群桩基础的复合体模型建立与应用

Composite materials model research on grouped piles foundation

在进行建筑物的上下部共同作用研究中,有限元法是一种非常重要的分析手段,但由于需要离散的区域很大,将桩和土体分别划分单元,所需要的单元数量巨大,常常会因受到计算机软件或硬件的限制,分析难以进行。本文按照复合材料力学的处理方法将群桩基础中桩—土体系作等效连续化处理,视为横观各向同性体,建立了桩土等效复合体的本构关系;按“分离模式”和“复合模式”两种情况进行了有限元对比分析,结果表明,等效复合体模型很好地反映出群桩基础的传力机理,对大型群桩基础进行等效连续化处理是完全可行的。采用本文建立的等效复合体模型,可大幅度减少下部基础单元的数量,提高了用有限元法研究建筑物的上下部共同作用的可操作性。

The finite element method is an important analysis in the researches on the interaction between super-structure and base, but the analysis is often difficult to deal with because the dispersed region required is large, the number of element needed is too large when the pile-soil system is compartmentalized into many elements, and the limitation of computer software or hardware is caused. In this paper the grouped piles foundation was treated as a kind of composite materials in terms of the equivalent continuum established method, and then the constitutive relation of the composite materials and the equivalent composite model were established. Compared with the computated results obtained by ＂the separated model＂ and ＂the composite model＂ on the basis of the analysis of finite element method, it was shown that the equivalent composite model reflected the load transfer mechanism of grouped piles foundation well, and the equivalent continuum method was proved to be feasible huge to grouped piles foundation. The equivalent composite model adopted could reduce the number of infrastructure base elements and accordingly develop the maneuverability of interaction between super-structure and base in use of the finite element method.