为了揭示新型注浆成型螺纹桩的承载力特性及桩土接触特性，利用二维离散元（DEM）数值分析不同螺纹间距的桩-土接触特性。在既有螺纹桩-土界面的大型直剪试验方案的基础上，建立模拟试验的离散元模型。通过模拟试验的伺服加载机制，实现在接触面法向上施加恒定的压力，然后水平移动接触面底板进行剪切，得到不同螺纹数下剪切位移与剪切应力的关系曲线、孔隙比分布图和力链传力机制。离散元分析表明，存在一个最优的螺纹间距，使接触面的极限抗剪强度最大；螺纹桩桩土接触面周围土体会出现一个拱形的破坏面，该微观机制与室内试验观察一致。

In order to find out the bearing capacity and failure mechanism of interface between new grouting-screw pile and soil, the discrete element simulation(DEM) has been used. The DEM model has been built under existing experiment plan of pile-soil interface. According to servo mechanism, the normal pressure on the interface can be unchanged. Then the baseboard is moved at constant velocity, and the relation between shear stress and shear displacement, contact force transport mechanism and the porosity distribution could be obtained when screws of different numbers are adopted. The results show that there is an optimal flutes pitch which can make sure the ultimate shear stress reach to the maximum. And the vaulted failure surface will appear around the pile-soil interface. Moreover, the micro mechanism has a good agreement with indoor experiment.