砂土中根式抗拔桩模型试验研究

根式抗拔桩是一种在桩身设置根键的新型变截面基础形式,合理的布置根键可以在提高基础承载力的同时降低工程造价。为了提高根式抗拔桩在工程中应用的效率和可靠度,基于模型试验方法,通过对普通抗拔桩和根式抗拔桩的对比分析,开展砂土中竖向上拔荷载作用下2组试桩的承载特性试验,测得不同荷载等级下桩身上拔位移、桩身轴力、桩侧摩阻力,并研究其分布规律。结果表明:根式抗拔桩承载力较普通抗拔桩大约提高57%;桩身轴力在有根键处变化显著,桩身侧摩阻力发挥由上向下传递,并在根键上下处达到极值。因此,在保证根键强度不受破坏和根键易于安装的条件下,尽量将根键位置设置在靠近桩底,是提高根式抗拔桩承载能力的有效方法之一。

Model Test on Rooted Uplift Pile in Sand

Rooted uplift pile foundation is a new type of foundation with variable cross-section with concrete roots jacking in the sidewall of caisson. Reasonable arrangement of roots could reduce construction cost while improving foundation’s bearing capacity. In an aim of enhancing the efficiency and reliability of applying rooted uplift piles in engineering, we compared the bearing capacity—to be specific, uplift displacement, axial force of pile shaft, and lateral frictional resistance—of ordinary uplift pile and rooted uplift pile in sand under different levels of vertical uplift load through model test. Results revealed that the bearing capacity of rooted uplift pile increased by 57% compared with that of ordinary uplift pile; the axial force of pile shaft changed significantly at roots; the lateral frictional resistance of the pile was transmitted from top to bottom, and reached the extreme value near the roots. In addition, setting the roots as close as possible to the bottom of pile is an effective way to improve the bearing capacity of rooted uplift pile in the premise of ensuring the strength of root not damaged and the installation of root convenient.