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Volume 31 (1994 - 199･･･
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Volume 31, Issue 3
Displaying 1-7 of 7 articles from this issue
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Koichiro SADO, Hiroyuki YOSHIMATSU, Hisao FUJITA1994 Volume 31 Issue 3 Pages 1-8_1
Published: December 15, 1994
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe determination of slip surface locations in landslide investigations plays the most important role, and has been generally decided by the experiences and subjectivity of the engineers.
In this paper, we discuss the determination method for slip surface locations in core observation by using a fuzzy set theory and try to quantify such experiential and subjective appreciations.
The results of applications to the field agree well with the real locations of slip surface. The relative certainty of core appreciations become distinct, so that we can discuss them quantitatively and systematically.View full abstractDownload PDF (1494K) -
The Feasibility for Susceptibility IndexTetsuya KUBOTA1994 Volume 31 Issue 3 Pages 9-15_1
Published: December 15, 1994
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSIt is desirable to know the location of landslide susceptible areas in order to avoid landslide disasters. However it is very difficult to find such places especially if they are concerning to primarily landslides. For this reason, topographical and geological features over the areas to investigate have been using to find out that kind of areas. In this paper, topographical “fractal” characteristics of landslides are discussed on the view of the tool for investigation of landslide susceptible areas. The “Fractal” is a mathematical theory that has debeloped by B. Mandelbrot in order to describe the quality of complex shapes or images in the nature. And, it is suitable to measure landslides complex topography. Here in this paper, Fractal Dimension of landslides “D” are discussed as a index factor for landslide susceptibility, and some example of D are also given. Finally, it has come to be clear that “D” can be an index for landslide susceptibility.View full abstractDownload PDF (1015K) -
Presently Active Landslides in an Ancient Primary Slide Mass at Higashinomyo, Niigata, Central JapanNobuyuki TAKAHAMA, Kaichi HAYAKAWA1994 Volume 31 Issue 3 Pages 16-23_1
Published: December 15, 1994
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe present Higashinomyo landslide, which began about 200 years ago, is a partial reactivation (secondary landslise) in an ancient primary slide mass which was formed before about 50 thousands years in the Late Pleistocene. The primary slide involved a surface area of about 2 km2 and an estimated volume of 108m3. The presently active surface area is 0.34 km2 at the center of the primary slide area with an estimated volume of 107m3. The most recent prior active phase of the secondary landslide at the site is 36 thousands years ago during the jomon period in the Holocene. The history of this slide suggests intermittent activity between relatively long dormant periods.
The present slide movement has multiple slip surface layers. The shallow movement in the coluvium is of the creep type, and the deep movement in the ancient slide mass, which is composed of the Miocene marine mudstone, is intermittent activity at intervals of several years.
The Higashinomyo landslide has often formed slide dams in the valley of the Aburuma-gawa River throughout its history. The last dam was formed by the 1783 landslide.View full abstractDownload PDF (7206K) -
Seiichi GIBO1994 Volume 31 Issue 3 Pages 24-30_1
Published: December 15, 1994
Released on J-STAGE: February 25, 2011
JOURNAL FREE ACCESSThis paper describes the introduction of a newly developed ring shear apparatus and its measurement accuracy. It has been pointed out that the conventional ring shear apparatus has the following disadvantages: sample loss by the squeezing during shearing process, periodic variation in the stress-displacement relation ship, and detection of normal stress acting on the shear surface. The new apparatus, as a goal, aims at solving the problems mentioned above, and attaining the high accuracy of measurement. In the new apparatus, the gap between the upper and lower confining rings can be made as small as 5μm-10μm, and the normal stress on the shear surface is improved to be measured directly from the actual vertical load. Furthermore, the time required for residual strength measurement was remarkably shortened by adoption of the function of the constant volume shear. The residual strength parameters measured with the new apparatus were found to be more appropriate than the parameters measured with the direct shear test. They also well corresponded to the parameters of the field-mobilized shear strength analyzed by the back analysis of a actual case.View full abstractDownload PDF (2206K) -
Haruo SHUZUI, Yoshiro KATO, Shinji ISHIMARU1994 Volume 31 Issue 3 Pages 31-36_1
Published: December 15, 1994
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThis paper summarizes the results of investigation into the geological properties of the Ryoke granite, which is the cause of the landslide happening on Hakata Isle, Ehime Prefecture, and discusses countermeasures against that kind of landside.
The granite, the weathering of which is now in propress, is widely distributed over the isle slopes. And the formation of a layer or stratum of soft or slippery material such as weathered rock in a certain plane would sometimes cause large landslides (about 100 meters in width, about 100 meters in length and about 20 meters in layer thickness) to occur.
The degree of weathering was only made clear by measuring the shape of cores, but also checked numerically in an ignition loss test. The landslide settled down as a result of provisional counterweight fill. Horizontal drilling was selected from the countermeasures examined, and has been performed up to the earth designed to be removed so far. Anchor works are constructed one after another.
As such sliding is regarded as a kind of autometamorphous rock mass-sliding, and as the cohesiveness of material increases at the base of the landslide, the effect of constructing anchor works is considered to be larger than that of increasing the factor of safety.View full abstractDownload PDF (867K) -
Takeshi KAMEI, Hiroaki SANO1994 Volume 31 Issue 3 Pages 37-42_1
Published: December 15, 1994
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSIn order to investigate the influence of hydrogen-ion concentration exponent on shear characteristics of bentonites, direct shear tests have been performed on bentonites with different hydrogen-ion concentration exponent.
As a result, it was found that shear strength increaseswith the decrease in hydrogen-ion concentration exponent. In addition, the diffusion characteristics (cυ-value and κ-value) increase with the decrease in hydrogen-ion concentration exponent. The reason for this may be considered that different diffusion characteristics and soil structures are developed with different hydrogen-ion concentration exponent. Engineering implication of the test results is turned out in making slope stability analysis. Hydrogen-ion concentration exponent, therefore, is one of the most important factors in considering slope stability.View full abstractDownload PDF (941K) -
Osamu TOMATSU, Chisato TAKENAKA, Junko WAKAMATSU1994 Volume 31 Issue 3 Pages 43-46
Published: December 15, 1994
Released on J-STAGE: February 25, 2011
JOURNAL FREE ACCESSTo investigate the water qualities of natural waters in Ohtaki Village, where there was a large-scale landslide caused by the Western Nagano Prefecture Earthquake in 1984, water samples on river streams were taken in 1992.(1) Water qualities are classified into three types, Ca-(HCO3) 2, Ca-SO4 and Na-HCO3 as likely results by YOSIOKA et al. and OKUDA et al. .(2) Water qualities are shown two principal components PCl which shows degree of weathering and PC2 which shows Ca-(HCO3) 2 type or Ca-SO4 type.(3) Water quality values of PC1 and PC2 on Denjo-river were small before the earthquake, and larger after it and gradually tend to decrease.View full abstractDownload PDF (579K)
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