新型扩挤支盘桩竖向承载特征FLAC^3D数值分析

苏晴晴 夏红兵

摘 要：针对新型扩挤支盘混凝土灌注桩的竖向承载力、沉降、桩侧摩阻力等竖向承载特性及桩身荷载传递规律的问题进行了数值模拟研究。研究表明：相对于等截面桩，扩挤多支盘混凝土灌注桩具有承载力高、沉降量小的特性，支盘桩的极限承载力相较等截面桩竖向承载力提高了100%，沉降量大幅减小，两者最大沉降差可达19.781mm。桩身轴力在支盘处变化突出，支盘分担竖向力效果显著；适当增加支盘的个数可以大幅减小桩底荷載，减缓桩侧摩阻力的增加速度。

关键词：扩挤多支盘桩；承载力；沉降；桩侧摩阻力；FLAC3D

中图分类号：TU473.1 文献标志码：A

文章编号：1672-1098（2017）06-0071-05

Abstract： In this paper， FLAC3D numerical study on the axial bearing behaviors and the load transfer behavior of the squeezed branch pile in terms of the vertical bearing capacity， the settlement and the lateral friction resistance of the new type of reinforced concrete filling pile. The results showed that compared with the common piles， the squeezed branch pile had the characteristics of higher bearing capacity and smaller settlement. The vertical bearing capacity was improved by 100%， the settlement was reduced greatly，with the maximum settlement difference up to 19.781mm.The axial force of the pile prominently changed at the support branches and the supporting branches shared the vertical force obviously； moreover increasing the number of the supporting branches could significantly decrease the pile bottom load and retard the lateral friction resistance of the squeezed branch pile.

Key words：squeezed branch pile； bearing capacity； settlement； lateral friction resistance； FLAC3D

近几年来，许多国内外学者对扩挤支盘桩的承载力特性进行了深入的研究，主要方法有现场载荷实验、室内试验和数值模拟。文献[1]通过扩挤支盘桩现场原位测试试验，并对单桩静载试验和桩身轴力测试结果进行分析，表明扩挤支盘桩的荷载-沉降曲线为缓变型，在加载初期，桩侧摩阻力发挥较好，加载后期，摩阻力以发挥到极致，所加荷载主要由支盘承担，并且支盘承担的荷载可以达到施加的总荷载的50%。文献[2]设计了室内模型试验装置来研究在不同土质中模型支盘桩在重复荷载作用下承载力特征和桩-土的相互作用机制。文献[3]除了对扩挤支盘桩进行理论研究外，还进行了大量的数值模拟讨论了扩挤支盘桩的承载力特性与盘径、盘距之间的关系，并提出了扩挤支盘桩在不同的破坏形势下，该桩的承载力和沉降量的计算公式[4]。……