DEM Modelling of Subsidence of a Solid Particle in Granular Media

Abstract

Granular media are materials possessing complex mechanical behaviour and can manifest themselves as solids or liquids, depending on their stress states. In this study, the subsidence of a solid particle (an intruder) in a granular medium was analysed using discrete element methods. 2D DEM simulations were performed to investigate the subsiding behaviour of an intruder with zero initial velocity (i.e., being placed onto the top surface of the granular bed) in a randomly generated granular bed. In addition, the effect of density ratio of the intruder to the particles in the granular bed on the subsiding behaviour of the intruder was explored. Furthermore, the effect of finite size of the granular bed (i.e. boundary constraints) on the subsiding behaviour of the granular bed was also examined. It has been found that the density ratio plays an important role in the subsidence of the intruder. When the density ratio is close to unity (i.e. the intruder and the particles in the bed have similar densities), the subsiding depth is almost zero, indicating that there is negligible subsidence. However, as the density ratio increases, the intruder subsides and penetrates through the granular bed, and the subsiding depth increases linearly with the density ratio. It was also observed that the finite size of the granular bed can affect the maximum subsiding depth, especially at the higher density ratios (say > 200) when a shallow bed was used.