颗粒介质的离散态特性研究

Effect of particle size on the sinking depth of an object supported by a granular bed

回顾了颗粒介质中应力的分布和传播模式以及物体在颗粒介质中运动所受阻力的研究进展,并报道了我们对颗粒体系中代表离散特性的颗粒尺寸效应对颗粒介质特性影响的研究.研究发现物体由于自身重量在颗粒介质中下沉的深度随着颗粒尺寸的增大单调减小;球体在下陷过程中受到的颗粒床的支撑力,除了在约1mm范围的表面作用区域以外,与下陷深度之间满足很好的幂率关系,幂值在1.5—1.0之间,并且此幂值随着颗粒尺寸的增大而单调减小.颗粒床的支撑力与下陷深度的幂率关系可解释为颗粒介质内部应力结构重组的宏观反应结果.

In this paper we briefly review the latest progress on the propagation of stress in granular bed and the resistant force of an object moving in granular media, and report our studies on the grain-size effect, which revals the discrete properties of granular media. We found that the sinking depth of a sphere on a granular bed driven by its own weight decreases monotonically with increasing grain-size. The supporting force of the granular bed experienced by the intruder sphere, during sinking, is measured. It is found that except for about 1 mm depth near the surface, the supporting force and the sinking depth of the sphere is related by a power-law with exponents between 1.5-1.0. The exponent decreases with increasing grain-size. This-size dependence of the power-law relation can be a macroscopic manifest of the reorganization of the stress chains in the granular system during the sinking process of the intruder sphere.