变截面螺纹桩是一种新型地基处理桩型。通过室内模型试验和数值模拟，研究了变截面螺纹桩的竖向承载特性，比较分析了变截面螺纹桩与普通螺纹直桩和普通圆柱形光面直桩承载特性的差异，以及螺纹结构参数和地基土体参数对变截面螺纹桩竖向承载能力的影响规律。结果表明，变截面螺纹桩的螺纹结构及圆台形桩身能大幅度提高侧摩阻力；相同地层条件下，变截面螺纹桩桩身材料利用率（极限荷载除以桩身体积）是普通等截面螺纹桩的1.3倍左右，是普通圆柱形光面直桩的3倍左右；变截面螺纹桩的结构参数中，螺纹宽度、厚度、间距及桩身截面变化率是影响单桩竖向承载力的重要因素，在工程设计中应予以充分考虑。

Variable cross-section thread pile is a new type of piles applied in ground improvement. The vertical bearing characteristics of variable cross-section thread pile are studied by means of laboratory model test and numerical simulation. The difference of bearing characteristics between variable-section thread piles and ordinary straight piles and plain cylindrical piles is analyzed. And the influence of thread structural parameters and foundation soil parameters on vertical bearing capacity of variable cross-section thread pile is comparatively analyzed. The results show that the thread structure of the variable cross-section thread pile and the round-shaped pile body can greatly improve the side friction. Under the same stratum condition, the material utilization ratio (ultimate load divided by pile body volume) of the variable cross-section thread pile is about 1.3 times that of the ordinary section thread pile, and is about 3 times that of ordinary cylindrical smooth pile. Among the structural parameters of the variable cross-section thread pile, the thread width, thickness, spacing and change rate of pile section are the important factors affecting the vertical bearing capacity of single pile, and should be fully considered in the engineering design.