螺杆桩竖向抗拔承载性能原位试验研究

In-situ Test Study on Vertical Uplift Bearing Capacity of Screw Pile

本文研究了螺杆桩的竖向抗拔承载性能,分别对螺杆桩与直杆桩进行了现场原位静载与内力测试试验,记录了不同荷载下桩身轴力分布情况,对比分析了螺杆桩与直杆桩竖向抗拔承载性能差异及原因。研究结果表明:在本文地层条件下螺杆桩的竖向抗拔承载力较直杆桩可提升5%~15%;随着上拔荷载增大,螺杆桩螺纹段侧阻优势开始发挥,桩轴力在螺纹段下降更快,轴力曲线呈折线;相同上拔荷载作用下,螺杆桩产生位移更小,其抗拔力主要由螺杆段产生,其上部直杆段侧摩阻力发挥水平不如直杆桩侧摩阻力。

In this paper,the vertical pull-out bearing capacity of the screw cast-in-place pile is studied.In-situ static load and internal force test are carried out on the screw cast-in-place pile and straight rod pile respectively.The axial force distribution of the pile under different loads is recorded,and the difference of vertical pull-out bearing capacity between the screw cast-in-place pile and straight rod pile and the reasons are compared and analyzed.The results show that the vertical uplift capacity of screw cast-in-place pile can be increased by 5%-15% compared with that of straight rod pile.With the increase of uplift load,the lateral resistance advantage of screw pile thread section begins to play,and the axial force of pile decreases faster in the thread section,and the axial force curve presents a broken line.Under the same uplift load,the displacement of the screw pile is smaller,and the uplift force is mainly generated by the screw segment,and the lateral friction of the upper straight rod segment is not as good as that of the straight rod pile.