Effects of bed longitudinal inflexion and sediment porosity on basal entrainment mechanism: insights from laboratory debris flows

Li, Pu; Wang, Jiading; Hu, Kaiheng; Shen, Fei

doi:10.1007/s10346-020-01618-w

Cited by 16 publications

(5 citation statements)

References 71 publications

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“…For the scour shape, a scour pit is evident at the entrance of the gully in the experiment, as observed by Haas 25 and Li 8 in their experiments. Li attributed the increasing size of the pit to a change in the direction of the subsequent debris flow.…”

Section: Discussionsupporting

confidence: 75%

“…There are still some shortcomings in the experiment. The grain size of the bed sediment in this experiment is relatively uniform, while that in the field always has a wider range, implying differences in porosity and granular viscosity between the field and the experiment 8,31 . These are important influencing factors and should be further considered in future experiments.…”

Section: Discussionmentioning

confidence: 72%

“…The debris flow is a kind of solid–liquid two-phase flow that contains a significant portion of mud, sand, and stones in the mountainous area 1 , 2 , and it rushes down mountainsides and spills out onto the alluvial fan to devastate life and property of local people 3 , 4 . As it descends gullies, debris flow entraps numerous loose materials, resulting in a several-fold increase in its volume, thus posing a serious threat to downstream safety 5 – 8 .…”

Section: Introductionmentioning

confidence: 99%

“…The research results have an important significance for revealing the disaster-causing phenomena and mechanisms of debris flows in the narrow-steep gully.The debris flow is a kind of solid-liquid two-phase flow that contains a significant portion of mud, sand, and stones in the mountainous area 1,2 , and it rushes down mountainsides and spills out onto the alluvial fan to devastate life and property of local people 3,4 . As it descends gullies, debris flow entraps numerous loose materials, resulting in a several-fold increase in its volume, thus posing a serious threat to downstream safety [5][6][7][8] .Debris flows that erupted in the Wenchuan strong earthquake zone are mainly gully-type, and one type of typical debris flow occurring in gullies with a small catchment area, a narrow channel, and a steep longitudinal slope has attracted attention. The post-earthquake area is rich in material sources, and once it rains, it is easy for debris flows to erupt in a short time in this kind of terrain 9 .…”

mentioning

confidence: 99%

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Experimental study of erodible bed scoured by the debris flow in the narrow-steep gully

Wu,

Ji,

et al. 2023

Sci Rep

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In recent years, debris flows have frequently erupted in the narrow-steep gully of the earthquake-hit Wenchuan region, displaying high flow velocities and powerful scouring abilities. However, few scouring studies in the narrow-steep gully have been conducted. A model experiment simulated the debris flow scouring process in a narrow-steep flume, in which several important physical parameters, including the debris flow density (ρ), flume slope (θ), and grain size of the sediment (D), were varied to investigate their influences on the erodible strength. The experimental flows were composed of 50 L of water and grains, which scoured 2.3 m of erodible bed down a steeply inclined flume. A high-speed camera photographed the scouring processes, while a 3D laser device captured the final bed shapes. The experiments show that the debris flow first collides with the sediment at the head of the gully to form a pit, which is enlarged by continuous impact; the velocity of the debris flow out of the pit is significantly reduced due to the change in flow direction, resulting in a much lesser scouring effect after the pit; and finally, the gully bed presents the shape of a pit at the entrance and a groove in the middle and rear. The critical scour slope, where the gully bed shows scouring, increases with increasing debris flow density but decreases with increasing grain size of sediment. Following scouring, the maximum scouring depth is further positively correlated with the flume slope. In narrow-steep gullies, the gully bed is extremely susceptible to scouring by debris flow with a low density, and even headward erosion appears, at which the maximum scouring depth only increased from 148.04 to 149.97 mm, but the erosion amount had a significant increase of 36.9%. The research results have an important significance for revealing the disaster-causing phenomena and mechanisms of debris flows in the narrow-steep gully.

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Section: Discussionsupporting

confidence: 75%

Section: Discussionmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Experimental study of erodible bed scoured by the debris flow in the narrow-steep gully

Wu,

Ji,

et al. 2023

Sci Rep

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“…Granular flow disasters, such as mudslides, landslides, and rock avalanches, frequently occur all over the world with characteristics of large scale, high mobility, long runout distances, and significant destructive power [1][2][3]. They can be triggered by earthquakes, extreme climate, and various human factors and result in significant casualties and economic losses [4,5].…”

Section: Introductionmentioning

confidence: 99%

Granular Flow Impact on Shed Tunnels and the Buffering Effect of Cushion Layers

Wei,

Wang,

Dai

2024

Applied Sciences

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Granular flow is one of the most destructive geological hazards in mountainous areas, posing a severe threat to the economy and personnel safety in the region. Shed tunnels are widely used for the prevention and mitigation of granular flow hazards. Thus, comprehensively studying the impact mechanisms of granular flows on shed tunnels is significant for disaster prevention and mitigation. This study adopts a combined approach of a physical model experiment and Particle Flow Code (PFC) simulation to investigate the impact force of granular flow on shed tunnels and the buffering effect of cushion layers. The influences of slope angle, cushion layer thickness, and cushion layer particle size are discussed. It is revealed that as the slope angle increases, the velocity of the granular flow and the impact force on the shed rise significantly. When the slope angle increases from 40° to 60°, the peak velocity surges by 25%, while the impact force intensifies by 2–3 times. Moreover, increasing the thickness of the cushion layer can mitigate the interaction between the granular flow and the shed tunnel, thereby enhancing structural safety. With an increase in cushion layer thickness from 0 to 200 mm, the impact force is reduced by approximately 50%. Meanwhile, reducing the particle size of the cushion layer effectively decreases the impact force, resulting in less kinetic energy and providing a stronger cushioning effect.

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Experimental study on a debris flow water-sediment separation structure of a funnel-type grating and its sorting characteristics

Wang

et al. 2023

Bull Eng Geol Environ

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Effects of bed longitudinal inflexion and sediment porosity on basal entrainment mechanism: insights from laboratory debris flows

Cited by 16 publications

References 71 publications

Experimental study of erodible bed scoured by the debris flow in the narrow-steep gully

Experimental study of erodible bed scoured by the debris flow in the narrow-steep gully

Granular Flow Impact on Shed Tunnels and the Buffering Effect of Cushion Layers

Experimental study on a debris flow water-sediment separation structure of a funnel-type grating and its sorting characteristics

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