扩底桩抗拔承载特性数值分析

基于通用软件ABAQUS，建立了扩底抗拔桩三维弹塑性有限元模型，通过对模型的计算与分析，探讨了扩底桩的抗拔承载特性。为验证数值模型的可靠性，将数值计算得到的荷载－位移关系曲线与试桩资料进行比较，两者吻合较好，表明本文所建立的模型可较好地模拟扩底抗拔桩的工作性状。通过计算与分析，探讨了扩底抗拔桩的轴力、侧摩阻力分布特征，桩身和扩大头周围土体变形与塑性应变的发展规律，以及扩大头的挤压作用对扩大头周围土体竖向应力的影响。同时，通过变动参数研究了扩大头的形状、土体的性质对扩底桩抗拔承载力的影响，结果表明，扩大头直径和扩大头周围土体的性质对抗拔承载力的影响较大，而扩底高度的影响相对较小。

Numerical Analysis of Behavior of Uplift Resistance of Piles with Enlarged Base

A three-dimensional elastic-plastic model of an uplift-resistant pile with enlarged base was constructed with the general-purpose software ABAQUS. The behavior of uplift resistance of the pile was studied with the finite element model. In order to validate the finite element model, the computational result was compared with that of an in-situ full-scale pile test. The comparison shows that the behavior of uplift resistance of piles with enlarged base can be simulated with the model. Then the distributional characteristics of axial force and frictional force, the developing regularity of deformation and plastic strain in soils surrounding the pile body and base, and the effect of the enlarged base to vertical stress in soils were studied. At the same time, by changing the parameters, the sensitivity was analyzed for different diameters, lengths, expansion angles of the enlarged base, and the characteristics of soils where the enlarged base was embedded; and the analysis shows that the diameter of the enlarged base and the characteristics of surrounding soils have relatively great effect on the uplift-resistant capacity while the effect of the height of the enlarged base is rather little.