Memory of fabric anisotropy in the static packing of granular materials

We look into the influence of the anisotropic distribution of fabric and force network on the angle of repose, which is technically accomplished by fabricating several trap doors underneath a mother granular heap with the angle of repose α, to generate two child heaps with the angles of repose β (for the left child heap) and γ (for the right child heap) through the particle removal. The results indicate that with the deposition plane orientation angle θ varying from 0° to 90°, β experiences a local minimum value at θ = 30°~45°, and γ takes a local maximum value at θ = 45°~60°. As the trap door position shifts towards the free surface of mother heap, β increases first and then decreases in the experiments, and γ rises monotonically, with the existence of relation γ > β ≈ α. We explore the micromechanical responses of granular heaps by DEM simulations and propose conceptual models to explain the experimental and numerical observations.