Journal of the Japan Landslide Society
Online ISSN : 1882-0034
Print ISSN : 1348-3986
ISSN-L : 1348-3986
Volume 42 , Issue 2
Showing 1-15 articles out of 15 articles from the selected issue
  • Yoji ITO, Satoshi YAMASHITA, Teruyuki SUZUKI, Hiroaki HIRATA
    2005 Volume 42 Issue 2 Pages 103-111
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
    The 2003 Tokachi-Oki Earthquake caused extensive ground collapses accompanied by slightly lateral displacement . subsidences, and lateral spreads of gentle slopes in the Kyowa area of Tanno Town, situated about 230km away from the epicenter. The direct inducement of such slope movements was the liquefaction of the volcanic ash that had artificially covered the valley. Especially, at Locality No.1 in the Kyowa area, liquefied volcanic ash of about 10, 000m3spouted from the slope to the sides, and a wide farmland collapsed. Such large ground collapses caused by lateral jetting of the liquefied volcanic ash are new phenomena and new landslide disasters induced by the earthquake.
    The old landforms of the liquefied and moved area were narrow waste-filled valleys and swamps formerly utilized as paddy but these were converted into the gently-sloping farmland by the land fill of the volcanic ash. Though the field of similar landform transition and ground condition is large in number, it is characteristic that the slope movements caused by the liquefaction of volcanic ash were confined to the fields where the reclaimed planes tilted to the south or south-southwest. In addition to, the dip direction of the reclaimed planes coincided with the direction of the main lateral displacement of the surface in each liquefied area. The dip direction of the reclaimed planes might have brought about the geomorphic effect.
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  • Hiroshi KAWABE
    2005 Volume 42 Issue 2 Pages 112-114
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
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  • Tamotsu NOZAKI, Yuji INOUE
    2005 Volume 42 Issue 2 Pages 115-120
    Published: July 25, 2005
    Released: June 28, 2010
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  • Akihisa TAKAHASHI, Hiroshi MORIYA, Shigeru OGITA, Shinro ABE, Takao YA ...
    2005 Volume 42 Issue 2 Pages 121-128
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
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  • Jing-Cai JIANG, Takuo YAMAGAMI
    2005 Volume 42 Issue 2 Pages 129-135
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
    Existing three-dimensional (3D) slope stability analysis methods based on limit equilibrium are comprehensively reviewed, and studies which have been conducted to evaluate the computational accuracy of these 3D methods are briefly summarized. The end effect (i.e. ratio of the 3D factor of safety to the 2D value) estimated using different methods of columns is also examined. It may be concluded that simplified analyses based on an extension of the ordinary method of slices (e.g. Hovland method) are not adequate for 3D slope stability computations because they assume zero intercolumn forces, do not satisfy equilibrium conditions, and more importantly, predict overconservative results leading to a partial or complete neglect of the end effect that should be evaluated properly by a 3D analysis. Consequently, the use of a rigorous method of columns that satisfies both force and moment equilibrium is strongly recommended for a realistic 3D evaluation of the slope stability.
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  • Yasuhiro TANAKA, Fawu WANG, Kayo NAKAMURA, Tatsunori MATSUMOTO
    2005 Volume 42 Issue 2 Pages 136-145
    Published: July 25, 2005
    Released: June 28, 2010
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    Due to a continual rainfall, a flowslide occurred in Yamashina area, Kanazawa City, Japan on November 8. 2002. The sliding mass was fully fluidized after slope failure and had deposited thickly in a bamboo area. The stratum around the landslide area was massive mudstone of Tertiary period. According to field investigation, the mudstone was classified into strongly weathered mudstone layer at top, densely cracked moderately weathered mudstone layer at middle and fresh mudstone layer at bottom . It is confirmed that the flowslide was initialized along the sliding surface between the densely cracked layer and the fresh layer, and the sliding mass moved in the strongly weathered mudstone layer. Based on the landslide motion simulation reproducing the Yamashina flowslide, the shear resistance at steady state in the strongly weathered mudstone area and the bamboo area were estimated as 10 kPa and 50 kPa respectively. It is concluded that the landslide with high mobility was caused by the low mobilization of shear resistance in the saturated strongly weathered mudstone with low permeability.
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  • Acase study of Shrawan danda landslide Butwal, Rupandehi, Nepal
    Bishnu Prasad GYAWALI, Toyohiko MIYAGI
    2005 Volume 42 Issue 2 Pages 146-158
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
    Landslide induced disaster is a serious problem in the mountainous terrain of Nepal. The landslides and debris flows cause losses of lives and properties, damage the nature and other infrastructures in the monsoon every year. The risk evaluation of landslides is to be most important for landslide hazard reduction . This paper is to focus on evaluating the potential landslide topography of Shrawan danda landslide which lies on the southern slopes of the Siwalik Hills and has created serious problems in Butwal, Nepal. The series of the investigation methods have been carried out to identify the characteristic of each factor of the micro landform of the landslide through interpretation of aerial photographs incorporated with the information of field survey and historical records. The maps and related tables were converted to digital format from the database that was the part of the geographical information system (GIS). The information of aerial photo interpretation has been used for risk evaluation of the landslide based on the AHP method.
    Firstly, Shrawan danda landslide was divided into three landside bodies (A, B and C) based on the geomorphological features of the landslide area. Secondly the distribution maps of the micro landform features were prepared by using GIS. Thirdly, the length, area and density of the micro landform features (scarps, blocks, bare lands and cracks) of the landslide bodies were calculated. After that, the detailed information of instability of the landform features of the landslide bodies were analyzed for risk evaluation. Finally the weight of risk value of the micro landform features produced by the AHP method were used for classifying the landslide bodies as one with high, moderate or low risk.
    The results show the weight of risk value of the landslide body A=44, B=90.4, and C=76.4 points. The weight of risk value of the landslide body B and C were found more than 70%. These landslide bodies are highly contributed by the number, length and density of the micro landform features which are perceived as high risk . The weight of risk value of the landslide body A was found between 30 to 70% which is moderately controlled by the number, length, area and density of the micro landform features that is perceived as moderate risk. Thus results of qualitative and quantitative estimation of the micro-landform features led by using GIS and numerical function, and the weight of the risk value of the micro landform features led by using Analytical Hierarchy Process (AHP) method synthesizing information of the aerial photo interpretation (API) provide a precise contribution to evaluate risk of a landslide in various environmental conditions.
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  • Teuku Faisal FATHANI, Hiroyuki NAKAMURA
    2005 Volume 42 Issue 2 Pages 159-168
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
    It is highly important to estimate the shear strength parameters at the critical slip surface of landslide in order to design effective countermeasures. This study aims to propose a new method for estimating a set value of shear strength parameters which satisfies two conditions: the calculated critical slip surface coincides with the actual slip surface and the obtained safety factor is equal to 1.0. Dynamic programming using simplified Janbu's method was applied as a tool to locate the critical slip surface that yields minimum value of safety factor. A specific case of submerged landslide was examined to demonstrate the efficiency and accuracy of the proposed method. Furthermore, the same method of analysis was applied to examine another 47 cases of landslides. It found that two relationships, one between the estimated cohesion (c) and the average depth of landslide and the other one between the internal friction angle (φ) and the inclination of slip surface, can be used for practical estimation of shear strength parameters. Further, the estimated shear strength parameters of submerged landslides have a reasonable agreement with the change in safety factor by the rising of reservoir level.
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  • Shun-ichi KIKUCHI
    2005 Volume 42 Issue 2 Pages 169-174
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
    In May 2000, a very substantial landslide occurred in Sapporo. It was later named the Usubetsu-gawa Landslide. A dendrochronological study using the tree ring-width of living trees in this landslide area was used to examine the response of the rings to disturbances owing to previous landslides. The tree ring-width chronologies in the active landslide area were poorly correlated with the average Usubetsu-gawa chronology made using living trees growing outside the landslide area. This was explained as resulting from repeated landslides that altered tree thickening owing to root breakage caused by surface cracking and to canopy gaps produced by fallen or tilted surrounding trees. The variation in the tree ring-width chronologies on various slopes and micro-landforms suggests differences in the movement history within the same landslide area.
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  • Yasuo ISHII, Kazunori FUJISAWA, Keiichi OTA
    2005 Volume 42 Issue 2 Pages 175-181
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
    To clarify the applicable conditions of the design formula of landslide pile from a modulus of deformation of landslide soil mass and pile bending stiffness, sensitivity analysis by the finite element analysis using the model slope which is changed by modulus of deformation of landslide soil mass, the pile bending stiffness and the piling position was carried. As a result of analysis, When β-lwhich is calculated by modulus of deformation of landslide soil mass and the pile bending stiffness become three or less, the moment obtained by finite element analysis become bigger than the moment obtained by long pile formula and finite length pile formula of the dowel pile.
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  • Hagerman Valley, ldaho
    Osamu NAGAI, Neal FARMER
    2005 Volume 42 Issue 2 Pages 182-183
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
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  • Round-table Talk/The Future View of FEM in Landslide Analysis
    Takeshi KUSUMOTO, Keizo UGAI, Hiroyuki YOSHIMATSU, Senro KURAOKA, Shih ...
    2005 Volume 42 Issue 2 Pages 184-187
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
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  • Keizo UGAI
    2005 Volume 42 Issue 2 Pages 188
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
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  • Landslide occurring in the area composed of Neogene tuff in Yamagata Prefecture
    Emi YOSHITA, Mutsutoshi FUKUDA, Wataru SUZUKI, Hiroshi ISHIKAWA
    2005 Volume 42 Issue 2 Pages 189-190
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
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  • 2005 Volume 42 Issue 2 Pages plate1-plate2
    Published: July 25, 2005
    Released: June 28, 2010
    JOURNALS FREE ACCESS
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