Behavior of grains in contact with the wall of a silo during the initial instants of a discharge-driven collapse

Abstract

We study experimentally gravity-driven granular discharges of laboratory scale silos, during the initial instants of the discharge. We investigate deformable wall silos around their critical collapse height, as well as rigid wall silos. We propose a criterion to determine a maximum time for the onset of the collapse and find that the onset of collapse always occurs before the grains adjacent to the wall are sliding down. We conclude that the evolution of the static friction toward a state of maximum mobilization plays a crucial role in the collapse of the silo.

Dynamics of silo deformation under granular discharge

“…Note that t e for all C processes is smaller than the minimum value of t r , our estimated lower bound for the duration of the mobilization process. This supports the idea, proposed in [24,25], that the collapse of the silo is triggered by partially mobilized friction. Moreover, the evolution of all C processes is fast compared to FFC processes.…”

“…This allows us to effectively predict the collapse at an early stage of the discharge. The existence of such early differences between reversible and irreversible processes indicates that the collapse is triggered by partially mobilized grain-towall friction, as proposed in [24,25]. We also observe evidence of slow-fast dynamics in the evolution of the deformation and argue that it is caused by the intrinsic nonlinear behavior of the thin shell.…”

“…Namely, the growth of individual indentations almost stops and the subsequent changes of the pattern are predominantly due to the merging of neighboring indentations. Merging constitutes an important growth mechanism for indentations, which individually do not overcome a characteristic size determined by the properties of the shell [25]. In this way, very large indentations that cause the collapse of a silo can develop.…”

“…One must also consider that if w is too small fluctuations might compromise the results. Accordingly, we choose w ∈ [10,25], which corresponds to time scales between 0.3 s and 0.8 s. We find that the results are almost identical within this interval, thus we report the results only for w = 10.…”

The Friction Stress Distribution of Loose Materials to Silo Walls in Deep Pyramidal Silos

“…In the state of stockpiling loose materials, the mechanics behavior of the silos and the loose materials are all very complex (Jansseune A. et al, 2016a,b;Park H.W. et al, 2016;Jagtap P. et al, 2015;Colonnello C. et al, 2014). However, with the mature development of the finite element method and discrete element method, the numerical simulation method managed to contribute greatly to the silo research (Ding S. et al, 2015;Wang Y. et al, 2014;Gallego E. et al, 2010) and the loose materials or the solid particle behavior, including the powder friction angles, forces, stresses and so on (Hua X. et al, 2013;.…”