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)γ
H, 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)γ
H.
3) The maximum frictional stress also occurs at the same position with maximum normal stress.
4) Theoretical analysis gives a maximum normal stress of 0.5γ
KH(√2/
K-κ-√κ)
2/(1-κ
K)
2 at a radius
r=
H/√κ(2/
K-κ) and a normal stress at the center γ
H[1-
K2(
f-κ)(2/
K-κ-
f)/(1-κ
K)
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.
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