上拔荷载作用下扩展基础的颗粒流数值模拟

对砂土地基上承受上拔荷载作用的扩展基础进行颗粒流数值模拟，并与物理模型试验结果进行了对比。应用PFC2D程序，用细观力学的方法研究上拔荷载作用下砂土的颗粒结构分布、颗粒速度的变化。通过对剪切带颗粒速度的考察，分析颗粒间的咬合摩擦和滑动摩擦，判定出土中滑裂破坏面的位置。数值模拟分析了上拔荷载-基础位移曲线。通过实验室模型试验和现场原型试验，测得土中滑裂破坏体为曲面锥台与圆柱的组合体，其破裂面与颗粒流数值模拟的结果符合良好，并分析了荷载-位移关系。细观力学数值模拟的土中滑裂破坏面和荷载-位移关系能反映物理实物试验的宏观力学特性。

Particle flow code numerical simulation of extended foundation under the action of uplift loading

The displacement and fracture surface of extended foundation embedded in sandy ground under the action of uplift loading was numerically simulated by particle code method. The software PFC2D was adopted for computation. The particle distribution structure and variation of particle velocity field were investigated from the viewpoint of microstructure mechanics. According to the calculated velocity of particles in the shear band and the friction between particles the fracture surface can be determined. The simulated result is in good agreement with physical model test and prototype observation data. It is concluded that the numerical simulation by means of particle flow code method for solving micro mechanical problem is feasbile for studying the macro mechanical characteristics of fracture surface and relationship between loading and displacement taken place in sand.