三维弹塑性桩-土接触面单元及其在ABAQUS中的开发及应用

Development and Application of Three Dimensional Elastoplasticity Pile-soil Contact Element in ABAQUS

大直径超长钻孔灌注桩往往表现为摩擦桩,基桩承载力主要由桩侧摩阻力贡献。然而现有的计算方法由于无法考虑桩-土接触面剪切过程中的特性,对桩侧摩阻力的估计不准确。文章在弹塑性理论框架内推导了一种接触面本构关系,合理考虑了接触面在剪切过程中的剪胀等现象。基于隐式欧拉后退法推导了本构积分方程和相应的一致切线模量,并用ABAQUS所提供的UEL子程序接口,编写了接触面单元。通过与公开文献中的直剪试验进行对比,验证了文章所提出的接触面模型合理性以及本构积分算法的可靠性。最后将接触面单元用于三维桩土接触分析,结果表明传统的摩阻力计算公式偏于保守。

Large diameter and super long bored piles often behave as friction piles.However,due to the fact that the existing calculation method can not consider the characteristics of the pile-soil contact surface,the estimation of the lateral friction is not accurate.In this paper,the constitutive model of contact surface between pile and soil has been derived based on the elastic-plastic theory,in which the shear characteristic of contact surface was fully considered.Based on the implicit Euler method,the constitutive equation and the corresponding tangent modulus are derived.Then,the corresponding contact surface element has been written applying the UEL subroutine interface of ABAQUS.By comparing with the direct shear test in the open literature,the rationality of the contact surface model and the reliability of the constitutive integration algorithm are verified.Finally,the contact surface element is used to analyze the pile-soil contact,and the results show that the traditional friction resistance formula is conservative.