双护筒对旋挖桩受力变形特性的影响分析

为消除基坑范围桩身侧摩阻力的影响，对部分试桩在空桩段设置双层钢护筒，通过与其他未设置双护筒的试桩检测结果相对比，分析了两种类型试桩承载力差异，并与理论估算结果进行了对比，从桩土相对位移的角度分析了形成差异的原因，提出了昆明地区旋挖桩空桩段侧摩阻力近似估算。

Analysis on Impact of Double-layer Steel Cylinder upon Loading Deformation Behaviour of Rotary Digging Pile

To eliminate the influence of the side friction resistance of the pile within the range of the foundation pit, the double layer steel cylinders were installed on partial test piles in the invalid pile section. By comparison with test results of other trial piles without double layer steel cylinders, we analyzed the bearing capacity difference between two types of trial piles; also, we made the comparison with the results of theoretical calculation and analyzed the reasons of difference from the view of relative displacement between piles and soil. Finally, we proposed the approximate estimation of side friction resistance of rotary digging bored pile invalid pile section in Kunming area.