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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 reveal the bearing capacity characteristics and the contact characteristics between the pile and the soil, the two-dimensional discrete element (DEM) was used to analyze the pile-soil contact characteristics with different screw spacings. Based on the large scale direct shear test program of the screw pile-soil interface, a discrete element model of the simulation experiment is established. Through the servo loading mechanism of the simulation test, a constant pressure is applied in the normal direction of the contact surface, and then the base plate of the contact surface is horizontally moved to be sheared to obtain the relationship between the shear displacement and the shear stress under different thread numbers, the void ratio distribution map and Force chain transmission mechanism. Discrete element analysis shows that there is an optimal thread spacing, which maximizes the ultimate shear strength of the contact surface. An arcuate failure surface appears in the soil around the contact surface between the pile and the soil of the screw pile. The microscopic mechanism is consistent with the laboratory observation.