Reverse Janssen Effect in Narrow Granular Columns

Mahajan, Shivam; Tennenbaum, Michael; Pathak, Sudhir N.; Baxter, Devontae C; Fan, Xiaochen; Padilla, Pablo; Anderson, Caleb; Fernández‐Nieves, Alberto; Ciamarra, Massimo Pica

doi:10.1103/physrevlett.124.128002

Cited by 23 publications

(9 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These effects are known to depend on a complex interplay between the cross-sectional width of the packing, the height of the packing, grain size, friction, and packing history; estimating the magnitude of these effects is still an active area of research. However, recent experiments on confined granular packings suggest that, for our bead sizes and packing widths, boundary friction does not appreciably alter the stress transmitted through the packing (46). Furthermore, while we do not test grain/hydrogel size ratios R b /R i < 0.2, we expect that the extent of hindered hydrogel swelling is not strongly influenced by the grain size: Using the theory given in Eq.…”

Section: Directions For Future Workmentioning

confidence: 81%

Under pressure: Hydrogel swelling in a granular medium

Louf

O’Connell

et al. 2021

Sci. Adv.

View full text Add to dashboard Cite

Hydrogels hold promise in agriculture as reservoirs of water in dry soil, potentially alleviating the burden of irrigation. However, confinement in soil can markedly reduce the ability of hydrogels to absorb water and swell, limiting their widespread adoption. Unfortunately, the underlying reason remains unknown. By directly visualizing the swelling of hydrogels confined in three-dimensional granular media, we demonstrate that the extent of hydrogel swelling is determined by the competition between the force exerted by the hydrogel due to osmotic swelling and the confining force transmitted by the surrounding grains. Furthermore, the medium can itself be restructured by hydrogel swelling, as set by the balance between the osmotic swelling force, the confining force, and intergrain friction. Together, our results provide quantitative principles to predict how hydrogels behave in confinement, potentially improving their use in agriculture as well as informing other applications such as oil recovery, construction, mechanobiology, and filtration.

show abstract

Section: Directions For Future Workmentioning

confidence: 81%

Under pressure: Hydrogel swelling in a granular medium

Louf

O’Connell

et al. 2021

Sci. Adv.

View full text Add to dashboard Cite

show abstract

“…It should be noted that the difference between the pulling force and the pushing force is caused by the reverse of friction force on the sidewall. Recently, a similar phenomenon was explored as the reverse Janssen effect [25] . In our current experiment, with a suitable filling height the sidewall can remain stationary with the granules even when the load on the top of the sidewall exceeds 80 kg (the maximum load in the experiment).…”

Section: Methodsmentioning

confidence: 99%

External pressure dependence of granular orifice flow: Transition to Beverloo flow

Peng

Zhou

et al. 2021

Physics of Fluids

View full text Add to dashboard Cite

In this paper, we have designed and employed a suspended-wall silo to remove Janssen effect in order to explore directly the local pressure dependence of Granular Orifice Flow (GOF) systematically.We find that as Janssen effect is removed, the flow rate Q changes linearly with the external pressure.The slope α of the linear change decays exponentially with the ratio of the silo size and the size of the orifice Φ/D, which suggests the existence of a characteristic ratio λ (~2.4). When Φ/D > λ, α gradually decays to zero, and the effect of external pressure on the GOF becomes negligible, where the Beverloo law retrieves. Our results show that Janssen effect is not a determining factor of the constant rate of GOF, although it may contribute to shield the top load. The key parameter in GOF is Φ/D. In small Φ/D, the flow rate of GOF can be directly adjusted by the external pressure via our suspended-wall setup, which may be useful to the transportation of granules in microgravity environment where the gravity-driven Beverloo law is disabled.

show abstract

“…Hence, numerous literatures have demonstrated such contribution; Laubscher [13] proposed an empirical solution to describe the effect of the density and height of caved rocks. To describe the stress from caved rocks to the surrounding rocks in a confined space, Ren et al [25] conduct the scaled laboratory tests, and the results reveal this stress matches the solution for granular materials by Janssen [26]:…”

Section: Impact Of Caved Rocks On Stability Of Cylindrical Cavedmentioning

confidence: 87%

Cylindrical Caved Space Stability Analysis for Extension Prediction of Mining-Induced Surface Subsidence

Liu

Zhang

et al. 2021

Geofluids

View full text Add to dashboard Cite

Subsequent extension of surface subsidence after vertical caving leads to large-scale surface destruction, as well as associated geological hazards. The extension prediction for cylindrical caved space, which appears circular surface subsidence, is still an intractable issue, due to the absence of robust models. To fill such a research gap, this paper provides an analytical model for the depth and orientation where the shear failure of isotropic rocks around the caved space is firstly observed. The anisotropy of surrounding rocks is further involved to enable this model to analyze the slip failure along discontinuities in anisotropic stress state. The prediction for the extension of the surface subsidence in Xiaowanggou iron mine is conducted, and the comparison between the prediction and the observation in satellite images demonstrates the validity of the proposed model. Even though this model cannot provide a definite boundary after extension, the prediction for the orientation surface subsidence extends to contribute to mitigating the effect of geological hazards. Another contribution of this work is to provide guidance to mitigate the impact of surface subsidence on safety and environment, such as filling the interspace between large-sized caved rocks by dumping small-sized waste rocks or backfilling the caved space with waste rocks.

show abstract

Reverse Janssen Effect in Narrow Granular Columns

Cited by 23 publications

References 17 publications

Under pressure: Hydrogel swelling in a granular medium

Under pressure: Hydrogel swelling in a granular medium

External pressure dependence of granular orifice flow: Transition to Beverloo flow

Cylindrical Caved Space Stability Analysis for Extension Prediction of Mining-Induced Surface Subsidence

Contact Info

Product

Resources

About