Journal of the Japan Society of Erosion Control Engineering

[title in Japanese]

[in Japanese]

1989 Volume 42 Issue 3 Pages 1-3
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_1

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Generation and Flow Mechanisms of Floating Logs associated with Debris Flow

Yoshiharu ISHIKAWA, Takahisa MIZUYAMA, Makoto FUKUZAWA

1989 Volume 42 Issue 3 Pages 4-10
Published: September 25, 1989
Released on J-STAGE: July 01, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_4

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Experiments in a model channel have been conducted with respect to the motion and stopping conditions of floating logs in torrents. The formulas were obtained for calculating to determine the boundary between the start and stop of motion for floating logs on torrent bed. The passage and stop of the floating logs at narrow passes are also reviewed experimentally. The floating log capture ratio T at narrow pass can be calculated by the following equations:
T=1. 0 where F_r·≤0. 1
T=log(1/F_r·θ) where 0. 1<F_r·Θ<1. 0
T≅0 where 1≤F_r·Θ}
where, Fr is the Froude number, Θ=hw²/dl², h is the water depth immediately upstream of narrow pass (m), w is the width of narrow pass (m), d is the diameter of floating log (m) and l is the length of floating log (m) .
The results of surveys for the actual situation of floating logs accompanied with and generated by debris flows have been compiled, and criteria for calculating the number, volume and size of floating logs generated and flowed are proposed.
The maximum volume of floating logs generated per 1km² of catchment area υ_ga(m³/km²) can be estimated from the equation υ_ga=200/A, where A is the catchment area (km²) of a torrent. The maximum volume of floating logs generated in a torrent υ_g (m³) can be estimated frome the equation υ_g=0. 02V_y, where V_y is the volume of yield sediment (m³) .

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A Laboratory Study of the Flow Velocity in Small Rill

Payattipol Narangajavana, Jun Kataoka

1989 Volume 42 Issue 3 Pages 11-17
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_11

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In the present investigation, the exist of the Manning's equation for the flow velocity in small rill has been examined in relation to the V-shape and U-shape of rough surface fixed-bed rill models. We have conducted the laboratory system models for the flow hydraulics study, especially, we have focused at the velocity factor. Our collective results provided the extend knowledges on the characteristic of the flow hydraulics in small rill that it is supercritical and transitional range. Interestingly, the exponent in Manning's equation is likely existed for the exponent in formula of rill U-shape but, however, there is limitation in rill V-shape. Furthermore, we have found that in contrast to the good correlation between friction factor (f) and Reynolds number (Re) value of rill V-shape, the rill U-shape showed the inverse correlation of this both value that f decreased while Re increased. The exist of the Manning's equation in the rill U-shape and the limitation in rill V-shape might be explained by the different correlation of the mean velocity (V_q) and surface velocity (V_s), f and Re values occur in both different rill-shapes.

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Surface Runoff on Tephra-Covered Hillslope in Sakurajima Volcano

Takashi JITOUSONO, Etsuro SHIMOKAWA

1989 Volume 42 Issue 3 Pages 18-23
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_18

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Steel Piles Base of a Steel-Pipe-Made Permeable Sabo Dam

Takahisa MIZUYAMA, Nobubide ASAI

1989 Volume 42 Issue 3 Pages 24-26
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_24

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[title in Japanese]

[in Japanese]

1989 Volume 42 Issue 3 Pages 27-29_2
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_27

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[title in Japanese]

[in Japanese]

1989 Volume 42 Issue 3 Pages 30-37
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_30

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[title in Japanese]

[in Japanese]

1989 Volume 42 Issue 3 Pages 38-39
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_38

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[title in Japanese]

[in Japanese]

1989 Volume 42 Issue 3 Pages 39-42
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_39

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[title in Japanese]

1989 Volume 42 Issue 3 Pages 43-56
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_43

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[title in Japanese]

1989 Volume 42 Issue 3 Pages 57
Published: September 25, 1989
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.11475/sabo1973.42.3_57

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