乾燥粉粒体層における平板掘削の大規模DEMシミュレーション

抄録

Plate drag in granular materials is a simple but important because it provides an understanding of how tools interact with soil in soil cutting and tillage. We numerically study the response of dry granular materials to plate drag as a function of initial volume fraction of the materials using a large-scale discrete element method (DEM) simulation. In the simulation, a flat plate is translated horizontally through initially homogeneous materials with different volume fraction and the drag force acting on the plate is examined. The results show that a volume fraction-dependent bifurcation occurs in the force: in an initially loose granular bed, the force reaches an approximately constant value as the plate advances, while in an initially dense bed, the force oscillates with a large amplitude. The force oscillation is attributed to the periodic evolution of a shear band formed only in the dense bed. The behaviors of the drag force and shear band are in close agreement with those obtained experimentally in previous studies. Further analysis shows that the formation of the shear band is explained by the local dilation and compaction of the granular materials induced by the plate drag. In addition, the relationship between the evolution of the shear band and the drag force can be explained quantitatively by using a three-dimensional wedge model considering the variation of the local volume fraction inside the shear band.