Gravel accumulation in deposits of viscous debris flows with hyper-concentration

Wang, Yuyi; Tan, Rongzhi; Jan, Chyandeng; Tian, Bing

doi:10.1007/s11629-009-0120-9

Cited by 9 publications

(5 citation statements)

References 2 publications

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“…The loose debris was originally from easily-weathered slate, dolomite, and phyllite with a density corresponding to 2.65 t/m 3 . In addition, it is to be emphasized that the way that coarse and fine particles appeared in the vertical profile within loose debris was also considered on the basis of three vertical depositing patterns (i.e., normal, mixed, and inverse grading) reported in the earlier studies [36][37][38][39][40][41]. However, these findings of the vertical grading patterns were generally restricted to the post-event analysis and alluvial deposits.…”

Section: Factor Selectionmentioning

confidence: 99%

“…Specifically, coarse particles placed at the bottom layer and fine sediment on the top layer (Case E1, see Figure 2a), the coarse particles distributed on the top layer with fine grains at the bottom layer (Case E3, see Figure 2b), and both the coarse and fine particles fully mixed and covering the whole vertical profile (Case E2, see Figure 2c). In order to quantify this, a vertical grading coefficient ψ was proposed and written as In addition, it is to be emphasized that the way that coarse and fine particles appeared in the vertical profile within loose debris was also considered on the basis of three vertical depositing patterns (i.e., normal, mixed, and inverse grading) reported in the earlier studies [36][37][38][39][40][41]. However, these findings of the vertical grading patterns were generally restricted to the post-event analysis and alluvial deposits.…”

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confidence: 99%

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Study on the Formation and Initial Transport for Non-Homogeneous Debris Flow

Shu

Wang

et al. 2017

Water

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Non-homogeneous debris flows generally occur during the rainy seasons in Southwest China, and have received considerable attention in the literature. Regarding the complexity in debris flow dynamics, experimental approaches have proven to be effective in revealing the formative mechanism for debris flow, and quantifying the relations between the various influencing factors with debris-flow formation and subsequent transport processes. Therefore, a flume-based and experimental study was performed at the Debris Flow Observation and Research Station of Jiangjia Gully in Yunnan Province, to theoretically analyze favorable conditions for debris-flow formation and initial transport by selecting the median particle size d 50 , flow rate Q, vertical grading coefficient ψ, slopes S, and the initial soil water contents W as the five variables for investigation. To achieve this, an optimal combination of these variables was made through an orthogonal experimental design to determine their relative importance upon the occurrence and initial mobilization behavior of a debris flow and to further enhance our insight into debris-flow triggering and transport mechanisms.

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Section: Factor Selectionmentioning

confidence: 99%

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confidence: 99%

Study on the Formation and Initial Transport for Non-Homogeneous Debris Flow

Shu

Wang

et al. 2017

Water

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“…A typical bedding structure is that coarse grains (sometimes larger than 8 mm) accumulating on the surface, while the average grain size of the underlying layer is smaller poorly sorted (Enos, 1977;Major, 1995;Wang et al, 2009). This means that there exist roughening layers on the surface; and it is believed to influence the pore water pressure (Takahashi, 2014).…”

Section: Introductionmentioning

confidence: 99%

Grain Configuration Effect on Pore Water Pressure in Debris Flow

Yang

Liu

et al. 2021

Front. Earth Sci.

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The generation and development of excess pore water pressure directly affects the grain interaction in debris flow, which can significantly reduce the friction strength and promote the movement of debris flow. It has been found that coarse grains favor the increase in excess pore water pressure, but the effect due to grain configuration is missing in studies. In order to study the influence of grain configuration, field investigations and laboratory tests were carried out for two typical cases, i.e., flow with coarse grains evenly mixed (case I) and flow with coarse grains floating on the surface (case II). The results show that case II generates much higher excess pore water pressure than case I. The variation of relative excess pore water pressure (Ur) with time (t) satisfies the power function relationship: Ur = mt–n. Case II often has a smaller n value, meaning a low dissipation rate of excess pore water pressure. This study is helpful for a better understanding of granular effects in debris flow.

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“…Traditionally, the debris-flow deposits have been commonly observed to demonstrate: (i) normal grading; (ii) disorderly/mixed grading; and (iii) inverse grading of their coarsest fragments in the vertical structure (Naylor, 1980;Major, 1994 and1997;Wang, 2009;Starheim et al, 2013). However, these findings are typically restricted to the post-event analysis and used to infer information on the physical properties of debris flow, which is highly questionable since the accumulation of sediments could potentially be induced by a discrete pulse of single flow or an individual flow (Major, 1997).…”

Section: Introductionmentioning

confidence: 99%

Study on two-phase dynamic behaviours within non-homogeneous debris flow

Shu

Wang

Shao

et al. 2018

Proceedings of the Institution of Civil Engineers - Water Manag

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The non-homogeneous debris flows, consisting of a wide range of grain size, bulk density and demonstrating non-uniform velocity distributions, are commonly modeled as the two-phase flow. In adopting such an approach, a critical grain diameter to separate the solid and liquid phase, within such debris flows, can be determined through the principles of minimum energy dissipation. In the current study, an improved analytical approach using the resistance formula of water flow and mass conservation law is presented to determine the velocity of the solid and liquid phases within a non-homogeneous debris flow, based on the derived critical grain diameter. Some of the dynamic parameters required in the analysis are validated against the experimental data of a non-homogeneous, two-phase debris flow measured from the Jiangjia gully, Yunnan Province of China. The results show that, for the majority of non-homogeneous debris flows tested, the liquid phase exhibits higher velocity than the solid phase. However, as the bulk density of the debris flow increases, the solid phase tends to have higher velocity than the liquid phase. These findings are shown to have important implications on the vertical grading patterns of the bed deposits in depositional areas. The observations from the field studies indicate that the non-homogeneous debris flows with bulk density being significantly lower, close to and significantly higher than the critical value seem to exhibit normal (i.e. bed-to-surface vertical fining), mixed, and inverse (bed-to-surface vertical coarsening) grading patterns in the alluvial fan deposits.

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Gravel accumulation in deposits of viscous debris flows with hyper-concentration

Cited by 9 publications

References 2 publications

Study on the Formation and Initial Transport for Non-Homogeneous Debris Flow

Study on the Formation and Initial Transport for Non-Homogeneous Debris Flow

Grain Configuration Effect on Pore Water Pressure in Debris Flow

Study on two-phase dynamic behaviours within non-homogeneous debris flow

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