通过室内模型试验和数值分析研究了灌注螺纹桩的竖向承载机理．室内模型试验和数值反分析结果表明，灌注螺纹桩承载力取决于土体抗剪强度，承载力达到极限值时，桩周土体出现竖向剪切带．采用数值方法进行了参数分析，研究接触面属性、土体抗剪强度和螺纹桩构造尺寸等不同因素对其承载力的影响，进而分析承载机理及其规律．结果表明，影响螺纹桩竖向承载力的关键因素为土体抗剪强度指标、螺纹桩螺距和螺牙宽度．在此基础上提出了螺纹桩承载计算公式，并用现场试验和数值分析结果进行了验证．

The vertical bearing mechanism of screw piles was studied by the model test and numerical analysis. The results of the analysis show that the bearing capacity of the screw piles depends on the soil shear strength and a shear zone along the pile will take place in the surrounding soil under ultimate load. Parameter analysis was presented including the pile-soil interface properties, the soil shear strength, and the design parameters of the screw pile. The parameter study indicates that the key factors influence the vertical bearing capacity of screw piles are the soil shear strength, the screw pitch and the width of screw. A calculation method was obtained based on the field test and numerical results.