Basal interstitial water pressure in laboratory debris flows over a rigid bed in an open channel

Hotta, Norifumi

doi:10.5194/nhess-12-2499-2012

Cited by 16 publications

(20 citation statements)

References 14 publications

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“…In summary, no significant excess pore fluid pressure occur in the present tests. Such result agrees with the experimental findings of Hotta [], who carried out debris flow experiments with a similar sediment (mean grain size 2.9 mm) and the same slope (17°).…”

Section: Analysis Of Resultssupporting

confidence: 92%

“…The enlarged view of the time series of these quantities, reported in Figure , emphasizes that flow depth and basal normal stress, as well as high mixture density and sediment concentration increase at the front, keep nearly constant during the passage of the body, and decrease progressively during the passage of the tail. This behavior is quite similar to that observed in the laboratory by Hotta [] and in the Acquabona Watershed (Italian Alps) by Berti et al . [].…”

Section: Analysis Of Resultssupporting

confidence: 90%

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Propagation and deposition of stony debris flows at channel confluences

Stancanelli

Lanzoni

Foti

2015

Water Resources Research

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The fluid dynamics of stony debris flows generated in two small tributaries adjacent to each other and flowing into a main receiving channel was analyzed experimentally at a laboratory scale. The analysis on the propagation along the tributaries and deposition in the main channel provide information about sediment-water mobility, dangerous damming, and potential hazard. Debris flows were generated by releasing a preset water discharge over an erodible layer of saturated gravels material. As a consequence, the debris flow sediment concentration varied accordingly to the entrainment rate which, in turn, was strongly controlled by the tributary slope. The data collected by acoustic level sensors, pore fluid pressure transducers, and a load cell were used to characterize the evolution of bulk density and solid concentration of the sediment-water mixture. These two parameters were relevant to assess the stony debris flow mobility which contributes to determine the shape of sediment deposits in the main channel. The detailed bed topography surveys carried out in the main channel at the end of each experiment provided information on the morphology of these deposits and on the interplay of adjacent confluences. The influences of confluence angle, tributary slopes, and triggering conditions have been investigated, for a total of 18 different configurations. Within the investigated range of parameters, the slope angle was the parameter that mainly influences the stony debris flow mobility while, for adjacent confluences, the degree of obstruction within the receiving channel was strongly influenced by the triggering scenario.

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Section: Analysis Of Resultssupporting

confidence: 92%

Section: Analysis Of Resultssupporting

confidence: 90%

Propagation and deposition of stony debris flows at channel confluences

Stancanelli

Lanzoni

Foti

2015

Water Resources Research

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“…The debris flow velocity is mainly dominated grain size, slope angle, sediment concentration, etc. [18][19][20][21][22][23][24]. In this study, we took four variables into consideration using the GSA-RBF.…”

Section: Resultsmentioning

confidence: 99%

“…The debris flow velocity is mainly dominated by the following parameters: grain size, slope angle, sediment concentration, etc. [18][19][20][21][22][23][24]. Armanini et al [18] conducted the laboratory experiments studying the rheological behavior of high-concentration granular-liquid mixtures.…”

Section: Introductionmentioning

confidence: 99%

“…Armanini et al [18] conducted the laboratory experiments studying the rheological behavior of high-concentration granular-liquid mixtures. Hotta et al [19] developed an experimental system employing a differential gas pressure gauge to measure the basal interstitial water pressure in shallow laboratory debris flows in an open channel. Iverson et al [20] collected data of 28 controlled experiments to reveal that sediment mud content causes systematic differences in flow dynamics.…”

Section: Introductionmentioning

confidence: 99%

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An Approach to Predict Debris Flow Average Velocity

Cao

Song

Chen

et al. 2017

Water

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Debris flow is one of the major threats for the sustainability of environmental and social development. The velocity directly determines the impact on the vulnerability. This study focuses on an approach using radial basis function (RBF) neural network and gravitational search algorithm (GSA) for predicting debris flow velocity. A total of 50 debris flow events were investigated in the Jiangjia gully. These data were used for building the GSA-based RBF approach (GSA-RBF). Eighty percent (40 groups) of the measured data were selected randomly as the training database. The other 20% (10 groups) of data were used as testing data. Finally, the approach was applied to predict six debris flow gullies velocities in the Wudongde Dam site area, where environmental conditions were similar to the Jiangjia gully. The modified Dongchuan empirical equation and the pulled particle analysis of debris flow (PPA) approach were used for comparison and validation. The results showed that: (i) the GSA-RBF predicted debris flow velocity values are very close to the measured values, which performs better than those using RBF neural network alone; (ii) the GSA-RBF results and the MDEE results are similar in the Jiangjia gully debris flow velocities prediction, and GSA-RBF performs better; (iii) in the study area, the GSA-RBF results are validated reliable; and (iv) we could consider more variables in predicting the debris flow velocity by using GSA-RBF on the basis of measured data in other areas, which is more applicable. Because the GSA-RBF approach was more accurate, both the numerical simulation and the empirical equation can be taken into consideration for constructing debris flow mitigation works. They could be complementary and verified for each other.

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Coarse‐grained debris flow dynamics on erodible beds

2017

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A systematic set of flume experiments is used to investigate the features of velocity profiles within the body of coarse‐grained debris flows and the dependence of the transport sediment concentration on the relevant parameters (runoff discharge, bed slope, grain size, and form). The flows are generated in a 10 m long laboratory flume, initially filled with a layer consisting of loose debris. After saturation, a prescribed water discharge is suddenly supplied over the granular bed, and the runoff triggers a debris flow wave that reaches nearly steady conditions. Three types of material have been used in the tests: gravel with mean grain size of 3 and 5 mm, and 3 mm glass spheres. Measured parameters included: triggering water discharge, volumetric sediment discharge, sediment concentration, flow depth, and velocity profiles. The dynamic similarity with full‐sized debris flows is discussed on the basis of the relevant dimensionless parameters. Concentration data highlight the dependence on the slope angle and the importance of the quasi‐static friction angle. The effects of flow rheology on the shape of velocity profiles are analyzed with attention to the role of different stress‐generating mechanisms. A remarkable collapse of the dimensionless profiles is obtained by scaling the debris flow velocity with the runoff velocity, and a power law characterization is proposed following a heuristic approach. The shape of the profiles suggests a smooth transition between the different rheological regimes (collisional and frictional) that establish in the upper and lower regions of the flow and is compatible with the presence of multiple length scales dictated by the type of contacts (instantaneous or long lasting) between grains.

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Basal interstitial water pressure in laboratory debris flows over a rigid bed in an open channel

Cited by 16 publications

References 14 publications

Propagation and deposition of stony debris flows at channel confluences

Propagation and deposition of stony debris flows at channel confluences

An Approach to Predict Debris Flow Average Velocity

Coarse‐grained debris flow dynamics on erodible beds

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