EFFECT OF INTERGRANULAR FRICTION ON THE BOTTOM FORCE CHAIN OF TWO-DIMENSIONAL PARTICLE PILES WITH POINT DEFECTS1)

The force chain plays a decisive role in the macroscopic and microscopic mechanical properties of granular matter. Based on the discrete element method (DEM), a two-dimensional regular particle system is established to study the influence of the friction coefficient between the particles on the contact force distribution at the bottom of the system under different loads and different defect sizes. The results show that in a defect-free particle system, the contact force distribution at the bottom of the system is affected by the friction coefficient and the point load. As the coefficient of friction increases, the bottom contact force turns from the bimodal form through the platform, gradually to a single peak form. In a system with point defects, the coefficient of friction and the size of the defect have an effect on the force distribution. With a fixed load, as the size of the defect increases, the peak value of the bottom contact force increases significantly; the average value of the force on the bottom is significantly weakened, and the force transmission to the boundary is enhanced. The presence of defects on the central axis of the system weakens the bottom intermediate region. When the defect size exceeds 2 layers, the variation curve of the bottom intermediate force against the friction coefficient changes from an increasing curve to a linearly decreasing curve.