281 / 2024-03-14 20:20:17

The angle of repose and base stress distribution of granular piles: An experimental investigation

Granular pile;,angle of repose,stress dip,particle size,particle shape,funnel height

7、矿物与先进能源材料 > 4、资源材料与循环利用

The objective of this study is to identify the evolution of repose angle and vertical stress distribution of granular piles relied on laboratory experiments using local source method. Two different granular materials with distinct particle shapes and two packing methods were assessed. The effects of packing height, particle size, and particle shape on the two indices were investigated in free packing piles. An increase in particle size and particle irregularity increase the angle of repose; the confined packing piles have a larger repose angle compared to those free packing piles. Stress dip at the center was observed in all piles, which indicates this phenomenon is independent of granular material types and the existence of stress arch inside piles. We introduced a stress dip ratio to quantify the stress dipping effect. Stress dipping ratio exhibits similar patterns during formation of granular piles: an initial decrease and then tends to equilibrium. A higher funnel height from the base or pile apex would yield a larger vertical stress and a much slight stress dip under the pile. The results show that a middle particle size causes a peak stress dip ratio in standard sand piles and stress gathering also occurred near the center. When piles of confined packing, stronger stress arch is found in loose coal while larger radius of stress arch in standard sand; vertical stress reaches saturation state as stress arch expended to side wall of cylinder. In comparison with previous studies, the experimental data of lateral pressure shows similar development but lower than Ketchum value and standard value.