接触面单元对单桩位移应力的影响分析

Stress and displacement analysis of single pile considering influence of interface element

在用有限元法分析桩土相互作用的研究中,采用不同的接触面单元得到的结果必然不同。通过分别引入Goodman单元和Desai单元进行单桩有限元分析,研究接触面单元对桩土接触面力学特性及单桩位移应力的影响。分析认为:在桩顶荷载较小时两者的桩土接触面力学特性以及单桩的位移应力差别很小;桩顶荷载较大时,采用Goodman单元计算所得的桩顶沉降小,接触面剪应力大,轴力沿桩身递减快,桩端阻力和沉降都较小,单桩的竖向抗压极限承载力较大。

In the research of soil-pile interaction with finite element method, the results are consequently varying when we adopt different interface elements. Conducting finite element analysis of single pile separately with Desai element and Goodman element, we study the interface element＇s impact on the feature of interface mechanic behavior between soil and pile, and the stress and displacement behavior of the single pile. It is concluded that the differences of mechanical traits of contact interface and the differences of the stress and displacement are minor when the top load of pile is relatively low. On the contrary, when the top load of pile is comparatively high, the differences of two kinds of element are apparent in the following aspects： when adopting Goodman element the subside of the pile block is smaller than that of Desai element, the shear stress on the contact interface is bigger, and the axial force descends quickly along the pile body. The resistance and subside of the pile tip are smaller while the vertical allowable load capacity of single pile is greater.