Measuring the angle of repose of granular systems using hollow cylinders

摘要

The angle of repose of granular systems was investigated using hollow cylinders of different diameters and lengths and bases of different degree of roughness. The cylinders contained homogeneous samples of sand and gravel as well mixtures of sand and gravel with the sand either thoroughly mixed with the gravel or in layered systems. From the laboratory experiments, the following conclusions can be made: (a) the angle of repose of the granular systems was influenced by the degree of roughness of the base on which the grains came to rest. The rougher the base was, the higher was the angle of repose; (b) the mode of failure of the conical pile of grains was different depending if the base was rough or smooth. For a rough base, the failure took place on the face of the conical shape. For a smooth base, the failure took place at the base of the conical shape; (c) the lifting velocities of the cylinders were varied between a slow velocity (2 to 3 cm/sec) and a high velocity (7 to 8 cm/sec). The angle of repose was found to be smaller when the high velocity of cylinder lifting was used regardless of the bases¡¯ roughness; (d) the angle of repose was found to decrease in value as the amount of material contained in the cylinders increased in value; (e) the experiments on mixtures of sand and gravel indicated that their angle of repose decreased in value as the percentage of sand in the mixture increased in value; (f) the experiments on layered granular systems (gravel on top of sand) indicated that, regardless of the lifting velocity of the cylinders, the angle of repose of the layered systems decreased in value as the height of the sand layer in the composite increased in value; and (g) the results of the tests helped to explain the angle of repose found in real rock slopes.