颗粒堆密度变化对堆底压力分布的影响

The influence of density variation of a granular pile on the pressure distribution at its bottom

报道当一无黏性颗粒堆的中间部分密度略小于两边 ,从而使中部的弹性强度明显低于两边时 ,堆底的压力分布将在中间出现低陷 .对从一固定点 (或线 )缓慢散落颗粒而形成的圆锥形 (或楔形 )堆 ,这一微小的密度变化可能来自颗粒沿堆边滚落时对堆产生了一定的扰动拍紧效应 .计算表明用考虑了体弹模量随空间变化的弹性理论能很好地再现出观测到的压力分布 .

We report that when the density at the centre of a cohesionless granular pile is slightly smaller than the density at its sides, such that the elastic strength at the centre is evidently smaller than the strength at the sides, the pressure distribution under the pile will show a dip at the centre. For the conical (or wedge-shaped) piles formed by slowly pouring grains from a point (or a line), the small density variation may be due to the phenomenon that the pile is slightly tapped by the down-rolling grains along the pile surfaces. The computation shows that the observed pressure distribution can be well reproduced by the elastic theory with a spatial-varying bulk modulus.