On the Stress Distribution of Granular Materials Conically Piled on the Field

Two-way stress cells which can measure small normal and frictional stresses of granular materials on a wall are newly developed. With these cells, the stress distributions of granular materials (silica sand and millet grain) piled conically on a plate are measured and compared with the results of theoretical analysis. The results are as follows: 1) The maximum normal stress occurs at a distance of a quarter of the outer radius of the cone of the pile, which is about (0.7-0.8)γH, where γ is the apparent specific gravity and H denotes the height of cone. 2) The normal stress at the center is rather small, about (0.4-0.6)γH. 3) The maximum frictional stress also occurs at the same position with maximum normal stress. 4) Theoretical analysis gives a maximum normal stress of 0.5γKH(√2/K-κ-√κ)2/(1-κK)2 at a radius r=H/√κ(2/K-κ) and a normal stress at the center γH[1-K2(f-κ)(2/K-κ-f)/(1-κK)2], where κ denotes the internal friction coefficient, and K denotes the friction coefficient between granular material and the surface of plate. f is given by the formula (40). This agrees well with the experimental result.