Collapse of a liquid-saturated granular column on a horizontal plane

Abstract

Laboratory experiments on the collapse of a liquid-saturated granular column on a horizontal plane are reported. The trigger and the resulting dynamics of the collapse when occurring, as well as the shape of the final deposit, are characterized and analyzed in light of some dimensionless parameters, namely, the "column" Bond number Bo, the grain diameter to capillary length ratio d/l c , the initial aspect ratio a, the Stokes number St, and the initial volume fraction φ, by varying the properties of the interstitial fluid and of the grains, the geometry, and the compaction of the initial granular column. The main contribution of this study is to: (i) provide a diagram of the different regimes of collapse shown to be mostly controlled by capillary effect, (ii) develop simple criteria that capture the transitions between each regime in terms of critical values of the Bond number and the ratio of the grain diameter to the capillary length, (iii) extend a predictive model of the runout for dry collapses to the more general case of liquid-saturated granular collapses, and (iv) quantify the influence of a, St, and φ on the collapse dynamics and the shape of the final deposit in the capillary-free regime. A perspective description of the role of the interstitial fluid on the spreading of the granular medium, and more particularly of the driving role of the fluid, is discussed and argued on the basis of the present set of experiments.

Granular avalanches of entangled rigid particles

“…Entanglement is not the only mechanism that can lead to stable piles; such stable granular columns have been reported in the case of cohesive particles [54] and fluid-saturated particles [55]. In [54] Abramian et al conducted discrete and continuous two-dimensional simulations of the slumping of a column of cohesive particles and observed stable and collapsed regimes.…”

“…In [54] Abramian et al conducted discrete and continuous two-dimensional simulations of the slumping of a column of cohesive particles and observed stable and collapsed regimes. In [55] Bougouin et al examined the problem of the slumping of a fluid-saturated column of particles. In their study, varying the "column" Bond number, which compares gravity to capillary effects, also leads to stable and collapsed regimes.…”

“…While in the case of Bougouin et al (Abramian et al) the capillary (cohesive) force plays the role of the stabilizing mechanism, in our study the stabilizing effect comes from the inhibition of particle displacement resulting from the entanglement of the particles with their neighbors. In a future work, we might attempt to design a column Bond number for entangled granular media and carry out a dimensional analysis similar to that of [55] in order to capture the transitions between the observed regimes. As this column Bond number would be the ratio of the gravitational force over the stabilizing force, it would require including a measure of the aforementioned displacement inhibition due to the presence of entangled neighbours.…”

Frictional weakening induced by cohesion: the numerical case of cohesive granular failures

“…In this contribution, we are interested in characterising the failing behaviour of cohesive columns of varying cohe-sive properties. While most works on granular columns, including the collapse of cohesive material, concentrate on the run-out behaviour or the deposit shape after the collapse [21][22][23][24][25][26], the present work focuses on the first instant of the failure. The objective is twofold.…”

Study of the Dilatancy/Contraction Mechanism of Landslide Fluidization Behavior Using an Initially Saturated Granular Column Collapse Simulation

“…Furthermore, the Stokes number which indicates the relative importance of the grain inertia and fluid viscosity effects, grain/fluid density ratio, and initial aspect ratio considerably influence the collapse process and deposition profile (Bougouin & Lacaze, 2018). Research on wet and saturated granular column collapse events has demonstrate that the deposition profile is highly dependent on the water content, Bond number (Artoni et al, 2013;Gabrieli et al, 2013), Stokes number and initial solid volume fraction (Bougouin et al, 2019). Iverson et al (1997) noted that the results of field investigations, laboratory experiments and theoretical analysis suggested that the fluidization transformation of landslides can be attributed to the transition of Coulomb failure to partial or complete liquefaction, which is influenced by high pore pressures.…”