Landslides
Online ISSN : 1884-3956
Print ISSN : 0285-2926
ISSN-L : 0285-2926
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Volume 25, Issue 1
Displaying 1-5 of 5 articles from this issue
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  • Analysis of Creep Phenomenen by the Slip Surface Enlarging Model
    Hiroshi OHHMURA, Satoshi TSUCHIYA
    1988 Volume 25 Issue 1 Pages 1-6_1
    Published: June 25, 1988
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.3313/jls1964.25.1
    JOURNAL FREE ACCESS
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    The creep curve of landslide is composed of three parts in the process of strain to rupture. The curve of primary creep is approximated in the growth function . The secondary steady creep is given in a linear function. The tertiary creep to rupture is shown in an exponential curve . In order to forecast the rup ture time till the final. abrupt failure, the mathematical model on these creep curves was analyzed on the basis of the idea that the stress concentration would drive a progressive failure in landslide. It was presumed that the strain velocity of landslide depending on the stress would concentrate on the unbroken effective sphere which resisted the shear force in the potential sliding surface . Then the relationship between the concentrated stress and the strain velocity was given as follows, de/dt=-A/Sa, where e, t, A, and S are strain, time, coefficient, and effective unbroken sphere in the sliding surface respecti ly. By integrating the equation for the exponential power a=-1, 0, 1, ……, n at the initial condition S=S0 to t=0 and at the terminal condition S=0 to rupture time t=tr. the solutions corresponding to the each creep curve could be deducted and, given the fundamental base to fOrecast tee final rupture time.
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  • Estimation of Critical Volume of Rain to Surface Failure Occurrence
    Fnjiya KOMAMURA
    1988 Volume 25 Issue 1 Pages 7-12
    Published: June 25, 1988
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.3313/jls1964.25.7
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    The condition of slope failure occurrence depend not only on rainfall but on the states of slope. The discussions from both sides of rainfall and slope may be neccessary to elucidate the condition of slope failure.
    In this paper, an equation of safety factor including the degree of saturation as a parameter, in addi tion to the another parameters such as slope inclination, depth of soil layer, cohesion of soil, void ratio, etc. is introduced to estimate the volume of water in the soil layer at the time of occurrence of slope failure.
    The critical volume of rainfall which induce the slope failure is converted from the volume of water in the soil layer which is calculated by using the equation of the safety factor
    .The time to slope failure can be forecasted by knowing the time when the accumulated volume of precipitation reaches the critical volume estimated by the presented method in this paper.
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  • Detritus and Clay of Slide Horizon in the Ikutahara Landslide, Northeastern Hokkaido, Japan
    Hiroyuki MAEDA
    1988 Volume 25 Issue 1 Pages 13-20_1
    Published: June 25, 1988
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.3313/jls1964.25.13
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    The Ikutahara landslide, which is located at so-called “Green Tuff” region in northeastern Hokkaido, is the detritus slide type. The slide surface is in the clay with gravels of the middle part of the detritus. It is considered from the mode of occurrence and properties of the clay and the topography of the ancient landslide that the clay of slide horizon is probably a part of that of the ancient landslide. The mode of occurrence and mineral assemblage of the detritus and properties of the clay of slide horizon suggest that the clay of the landslide in 1976 and the ancient landslide in the Ikutahara landslide area had been formed mainly by the slaking of the pelitic rock and the weathering of the acidic igneous rock.
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  • The Variation Characteristics in the Snow-melting Water, Pore Water Pressure, Groundwater Level and Underground Temperature in Nigorisawa Landslide Area
    Shoji OGAWA, Toshio IKEDA, Takeshi KAMEI, Tadashi WADA, Toshihide HIRA ...
    1988 Volume 25 Issue 1 Pages 21-27_1
    Published: June 25, 1988
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.3313/jls1964.25.21
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    To investigate the variation characterisitics of the snow-melting water, pore water pressure, groundwater level and underground temperature during snow-melting season in landslide areas, the field investigations were carried out in Nigorisawa landslide area.
    The following conclusions were developed;
    i) One of the main factors causing landslides may be considered as the seepage into the undergrounds of the large quantity of snow-melting water. In addition, the time lag between upper and lower parts of the soil mass with respect to pore water pressure was observed.
    ii) The seepage time into the undergrounds of snow-melting water may be predicted by measuring thetemperature and underground temperature.
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  • [title in Japanese]
    [in Japanese]
    1988 Volume 25 Issue 1 Pages 28-40
    Published: June 25, 1988
    Released on J-STAGE: June 28, 2010
    DOIhttps://doi.org/10.3313/jls1964.25.28
    JOURNAL FREE ACCESS
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