Journal of the Japan Society of Erosion Control Engineering
Online ISSN : 2187-4654
Print ISSN : 0286-8385
ISSN-L : 0286-8385
Volume 52 , Issue 3
Showing 1-14 articles out of 14 articles from the selected issue
  • Hiromasa HIURA
    1999 Volume 52 Issue 3 Pages 1-2
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Chang-Woo LEE, Yasuhiro SHUIN, Masakazu SUZUKI, Takehiko OHTA
    1999 Volume 52 Issue 3 Pages 3-10
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    A new simple shear apparatus was developed to evaluate the effect of soil suction on soil strength during shear deformation. The new apparatus clearly depicts shear deformation. It is thus most suitable for evaluating the effect of shear reinforcement by tree roots because it can preserve the fixed shear zone for the duration of the shear test. The new apparatus consists of the shear box (acrylic resin, 20cm×20cm×15cm) and the soil suction control section (poly-vinyl chloride pipe; 19.8cm in diameter, 50cm long). Using Toyoura standard sand, we evaluated the shear strength obtained by the new apparatus then estimated the effects of soil suction as related to soil strength and it's parameters (apparent cohesion and internal friction angle).
    The results show that soil suction affects the soil strength, which depends on shear strain. The internal friction angle does not change under various soil suction conditions, but the apparent cohesion, which reached a peak in suction of-45 cmH2O near the critical capillary head, was effected by soil suction. The effect of soil suction on apparent cohesion abruptly changed in the range of 1 to 5% shear strain. These results demonstrate that the effect of soil suction on soil strength and apparent cohesion depends not only on shear failure but also on the process of shear deformation, which is significant in the range of 1 to 5% shear strain.
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  • Kazuki MATSUMURA, Junichiro TAKAHAMA
    1999 Volume 52 Issue 3 Pages 11-17
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    The mechanism of surface slope failure in a mountainous area was studied considering the two methods mentioned below. The one was the saturated stress analysis by Terzaghi's theory and the other was the unsaturated stress by Bishop's theory. Because the vertical stress is in a low level, in the case of slope failure on a shallow slope, the soil strength due to the water suction under unsaturated conditions was recognized to play important roles. The results have been confirmed through the study of slope failure in windfall trees area of northern part of Kyushu Island with the two methods. We obtained the critical rainfall intensity for causing slope failures, as assuming the average rainfall intensity to be 30mm/hr within 6 hours duration.
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  • Takashi YAMADA, Yasuhiro DOI, Noriyuki MINAMI, Takaaki AMADA
    1999 Volume 52 Issue 3 Pages 18-23
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    In the present design criteria, woody debris trapping capacity by impermeable type Sabo dam is estimated to be less than 1% of sediment control volume in debris flow zone. However, it has been reported that the impermeable type Sabo dam, already filled with sediment, traps woody debris more than the criteria. Hence, it has become necessary to review this issue.
    Authors analyzed the data of the trapped woody debris by impermeable type Sabo dams. Furthermore, we conducted flume experiments by using various lengths of wood models. Consequently, it was confirmed that impermeable type Sabo dams showed high woody debris trapping rates in some cases. Following results have been obtained by this study.
    1) Woody debris trapped by impermeable type Sabo dams are classified in three patterns, a) trapped by spillway clogging, b) trapped by the mixing of the debris flow in the sediment and c) trapped by friction in the sediment trapping zone.
    2) The impermeable type Sabo dam, already filled with sediment, traps 13% of sediment control volume of the woody debris.
    3) The maximum lengths of the wood in the trapped woody debris by clogging the spillways are more than 1.3 times of the width of the spillways.
    4) The two strong factors concerning the woody debris trapping rate are the relation between the maximum wood length and the width of the spillway, and the sediment filling condition of the impermeable type Sabo dam.
    5) Woody debris trapping rate increases by mixing long wood models in the woody debris.
    6) Woody debris trapping rate increases in proportion to the mixture rate of long wood models in the woody debris. However, there are some exceptions to this relation and this subject is necessary to be investigated in future studies.
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  • Shigekiyo TABATA, Yoshifumi HARA, Kimio INOUE
    1999 Volume 52 Issue 3 Pages 24-33
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    The epicenter of the Nohbi Earthquake that shook on 28 October 1891 was on Midori, Neo village in Gifu prefecture, Central Japan. The 1891 Nohbi Earthquake had the greatest intensity, which was Magnitude 8 on historical intraplate earthquakes in Japan. There had been remained many photographs, old maps and publications which recorded calamities and victims, when the time was soon after shaking. The purpose of this paper is to investigate the real situations of sediment movements caused by the Nohbi Earthquake, using recoiled visual and literatures data of the disaster in combination with geological and geomorphological analysis.
    The 1891 Nohbi Earthquake triggered thousands numbers of slope-failures. Topographical character of slope-failure triggered by main shock has spread width on the riverside slope and partly long length of failure reached from mountain ridge to slope foot. The rate of slope-failure area in the Neo River valley is about 10.9% (study area, 99.3km2). Reading the old maps, dammed lakes were made and broken on eight locations in the Neo River system by moving of landslides and earthquake.
    Most landslides that were likely triggered by the 1891 Nohbi Earthquake continued to occur within study area, even processing in several decades. Geologically, these large-scale landslides caused by caprock structure, lie beds of hard consolidated limestone.
    The inventory of disaster after the 1891 Nohbi Earthquake is as follows;
    1) Thousands numbers of slope-failures on 28 October 1891 by the Nohbi Earthquake : in the Neo River valley,
    2) Landslides and debris flows on 8 December, 1891 by snowmelt and rainfall after 40 days Kaminoyama & Takao landslide,
    3) Landslides on 5 August, 1895 by local severe rain after 4 years: Nannodani large-scale landslide,
    4) Landslides on 13 september, 1965 by local severe rain after 74 years: Neo-Shiratani, Tokuyama-Shiratani, & Koshiyamadani large-scale landslide.
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  • Masahiro KAIBORI, Yoshiharu ISHIKAWA, Motoyuki USHIYAMA, Tetsuya KUBOT ...
    1999 Volume 52 Issue 3 Pages 34-43
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
    Disasters caused by many debris flows and slope failures under the effect of the active baiu-front occurred in the western part of Hiroshima Prefecture on June 29, 1999. The rainfall was characterized by the distribution of very locally heavy intensity of 50 mm/hr. The concentrated damaged areas, where we could easily find out some inherent factors such as geological, geographical and vegetational properties, fitted in such zones of high hourly rainfall. We think that the rainfall patterns as the inducing factors were very important and decisive. Although the scales of most debris movements and slope failures were not very large, many victims and lots of damages were found in the residential areas. So the disaster prevention system must be more intensively promoted with the consideration of ideal land utilization.
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  • Shinya HIRAMATSU, Yoshiharu ISHIKAWA, Nobutomo OSANAI, Iwao MIYOSHI
    1999 Volume 52 Issue 3 Pages 44-49
    Published: September 15, 1999
    Released: April 30, 2010
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  • Yuji SORIMACHI, Noriyuki MINAMI, Takashi YAMADA, Katsuo SASAHARA, Masa ...
    1999 Volume 52 Issue 3 Pages 50-54
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Chang-Woo LEE, Yasuhiro SHUIN, Masakazu SUZUKI, Takehiko OHTA
    1999 Volume 52 Issue 3 Pages 55-58
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Koji SUZUKI, Eiji IWANAMI, Koso MIKAMI, Satoshi HIGASHIKAWA, Toshihiro ...
    1999 Volume 52 Issue 3 Pages 59-62
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Satoshi KASUGA
    1999 Volume 52 Issue 3 Pages 63-69
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Kiyoshi NAKANISHI
    1999 Volume 52 Issue 3 Pages 70-75_2
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • Hideaki MARUI
    1999 Volume 52 Issue 3 Pages 81-84
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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  • 1999 Volume 52 Issue 3 Pages A1-A2
    Published: September 15, 1999
    Released: April 30, 2010
    JOURNALS FREE ACCESS
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