Mobility of dry granular flows of varying collisional activity quantified by smart rock sensors

Coombs, Scott; Apostolov, Artur; Take, W. Andy; Benoît, Jean

doi:10.1139/cgj-2018-0278

Cited by 9 publications

(8 citation statements)

References 20 publications

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“…The physical properties of a representative sample of 30 beads were measured and tabulated by Coombs et al. (2019). The beads were found to have an average diameter of 3.85 mm, grain sphericity of approximately 95%, and grain density of 2,241 kg m −3 .…”

Section: Experimental Setup and Methodologymentioning

confidence: 99%

“…These beads were chosen for their pseudospherical shape, relatively uniform diameter, and ability to be reused for multiple trials with minimal breakdown. The physical properties of a representative sample of 30 beads were measured and tabulated by Coombs et al (2019). The beads were found to have an average diameter of 3.85 mm, grain sphericity of approximately 95%, and grain density of 2,241 kg m −3 .…”

Section: Materials and Preparationmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Pore Fluid on Grain‐Scale Interactions and Mobility of Granular Flows of Differing Volume

et al. 2022

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The presence of a pore fluid is recognized to significantly increase the mobility of saturated over dry granular flows. However, the mechanisms through which pore fluid increases mobility may not be captured in experimental flows of small volume typical of laboratory conditions. Here we present the results of dry and initially fluid saturated or “wet” experimental flows of near‐monodisperse coarse‐grained ceramic particles in a large laboratory flume for five source volumes of 0.2–1.0 m3. Measurements include flow height, velocity profile, pore pressure, and evolving solid volume fraction, as well as the final deposit shape. The dry experiments constrain the frictional properties of the common granular material and comparison with wet flows permits an independent evaluation of the interstitial fluid effects. These results demonstrate that flow dilation and strong variation in the velocity profile are directly linked to a greatly increased mobility for wet granular flows compared to dry, and a significant influence of scale as controlled by source volume on flow behavior. Excess pore pressure need not be present for these effects to occur.

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Section: Experimental Setup and Methodologymentioning

confidence: 99%

Section: Materials and Preparationmentioning

confidence: 99%

Influence of Pore Fluid on Grain‐Scale Interactions and Mobility of Granular Flows of Differing Volume

et al. 2022

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“…Dams were constructed in the 36 m long horizontal portion of the Queen's University Landslide Flume (e.g., Bullard et al., 2019; Coombs et al., 2020; Miller et al., 2017). The crest of the dam was positioned upstream of the midpoint of the horizontal portion of the flume to create a larger volume downstream of the dam than upstream (Figure 2).…”

Section: Experimental Methods and Materialsmentioning

confidence: 99%

Effect of Upstream Dam Geometry on Peak Discharge During Overtopping Breach in Noncohesive Homogeneous Embankment Dams; Implications for Tailings Dams

Walsh

McDougall

Evans

et al. 2021

Water Resources Research

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Tailings dams differ from conventional water‐retaining dams in design, materials retained behind the dam and used in construction of the dam, and the inclination of the upstream face of the dam. In this paper, we isolate the effect of upstream slope angle on behavior during overtopping breach. Six 1 m high homogeneous fine sand dams were constructed with upstream slope angles varying between 10.0° and 30.0° and brought to failure by V notch overtopping. Slope angle was observed to define the height of flow over the erosional breach crest hydraulic control structure that forms in the upstream face of the dam, with higher peak outflow corresponding to steeper upstream slope angles. A semiellipse was observed to be an excellent approximation of the geometry of the breach throughout the rising limb of the hydrograph to peak outflow. This observation permitted the use of the Ramanujan approximation for perimeter of an ellipse to define a mathematical relationship between breach width and arc length. A simplified method to predict the rising limb of the outflow hydrograph was then proposed based on the assumption of linear growth of breach width coupled with a semielliptical breach geometry. These findings show that hazard analysis for overtopping failure should consider the effect of upstream slope angle on peak outflow.

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“…The solid material selected for granular flow experiments is the 3 mm nominal size Denstone® 2000 Support Media provided by Saint-Gobain Norpro, a product of ceramic pseudo-spheres with an average grain size of δ = 3.85 mm; this product, which has previously been used in Raymond [22], Coombs [23], Taylor-Noonan, et al [24], is considered suitable for multiple test runs due to its hardness (ensuring particle characteristics do not change between tests), roughness (not explicitly measured but particles are rough to the touch), sphericity and uniformity. The particle size was also chosen to ensure that excess pore pressure (above hydrostatic) would be unlikely to be produced in wet or saturated tests.…”

Section: Methodsmentioning

confidence: 99%

Fluid effects in model granular flows

Zhao,

Take,

Kaitna

et al. 2023

Granular Matter

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Pore fluid plays a crucial role in many granular flows, especially those in geophysical settings. However, the transition in behaviour between dry flows and fully saturated flows and the underlying physics that relate to this are poorly understood. In this paper, we report the results of small-scale flume experiments using monodisperse granular particles with varying water content and volume in which the basal pore pressure, total pressure, flow height and velocity profile were measured at a section. We compare the results with theoretical profiles for granular flow and with flow regimes based on dimensional analysis. The runout and the centre of mass were also calculated from the deposit surface profiles. As the initial water content by mass was increased from zero to around 10%, we first observed a drop in mobility by approximately 50%, as surface tension caused cohesive behaviour due to matric suction. As the water content was further increased up to 45%, the mobility also increased dramatically, with increased flow velocity up to 50%, increased runout distance up to 240% and reduced travel angle by up to 10° compared to the dry case. These effects can be directly related to the basal pore pressure, with both negative pressures and positive pore pressures being measured relative to atmospheric during the unsteady flow. We find that the initial flow volume plays a role in the development of relative pore pressure, such that, at a fixed relative water content, larger flows exhibit greater positive pore pressures, greater velocities and greater relative runout distances. This aligns with many other granular experiments and field observations. Our findings suggest that the fundamental role of the pore fluid is to reduce frictional contact forces between grains thus increasing flow velocity and bulk mobility. While this can occur by the development of excess pore pressure, it can also occur where the positive pore pressure is not in excess of hydrostatic, as shown here, since buoyancy and lubrication alone will reduce frictional forces. Graphical abstract

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Mobility of dry granular flows of varying collisional activity quantified by smart rock sensors

Cited by 9 publications

References 20 publications

Influence of Pore Fluid on Grain‐Scale Interactions and Mobility of Granular Flows of Differing Volume

Influence of Pore Fluid on Grain‐Scale Interactions and Mobility of Granular Flows of Differing Volume

Effect of Upstream Dam Geometry on Peak Discharge During Overtopping Breach in Noncohesive Homogeneous Embankment Dams; Implications for Tailings Dams

Fluid effects in model granular flows

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