桩侧注浆抗拔桩离心模型试验与原位测试分析

通过离心机模型试验研究了注浆对接触面特性、抗拔桩荷载-位移曲线及桩侧摩阻力的影响,揭示了注浆提高桩身侧摩阻力发展规律和抗拔承载机制,并进一步将离心机模型试验的结果与原位试验结果进行了对比分析。研究表明,注浆桩侧摩阻力的发挥呈现一个渐进过程,桩身上部极限摩阻力率先发挥,并逐渐向中下部发展;注浆后桩侧极限桩侧摩阻力得到提高,而发挥极限状态所需的桩-土相对位移减小,上拔加载过程中,桩侧上部和下部极限摩阻力增幅较大,中部增幅较小。离心与现场试验一致表明,桩侧注浆显著提高了桩的抗拔刚度及极限承载能力。

Centrifuge model test and in-site observation on behaviors of side-grouting uplift pile

A serious of centrifuge model tests of side-grouting uplift piles is performed to gain an insight into the mechanism of side-grouting and its effect. Mechanical properties of the contact surface, load-displacement curves and the development of skin friction resistance are discussed and compared with the in-situ test results. A further research shows that the development of side friction on uplift piles is a progressive procedure, with a leading increase of skin friction resistance at the upper part of the pile and followed by an increase of skin friction resistance at the lower part. Side-grouting leads to an increase in the ultimate skin friction resistance and a decrease in the relative pile-soil displacement at the ultimate state. Compared with the non-grouting pile, the side-grouting pile has a higher growing skin friction in the upper and lower part than that in the middle part. Both the centrifuge model and in-situ tests illustrate that the pile with side-grouting has significantly larger uplift stiffness and capacity than that without side-grouting.