Journal of the Japan Society of Engineering Geology
Online ISSN : 1884-0973
Print ISSN : 0286-7737
ISSN-L : 0286-7737
Volume 17, Issue 4
Displaying 1-4 of 4 articles from this issue
  • Keiji MIYAJIMA
    1976 Volume 17 Issue 4 Pages 153-167
    Published: December 30, 1976
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Ohnaruto Bridge, one of the Honshu Shikoku connecting bridge, is a suspension bridge of 876m center span located in Naruto Straits.
    Foundation rock consists of the Cretaceous sandstone and shale which have remarkable stratifications of monoclinic structure dipping to SE at 45°-50°. Engineering propertes of the submarine foundation rock were researched by many core drillings, in-situ load tests in the holes and geophysical loggings.
    Estimation for the strength of rock mass was performed mainly by the deformation modulus of in-situ load test and total point method which was attempted for the stratified rock of Ohnaruto Bridge foundation. This method is a kind of synthetic classification of rock grade evaluating characteristics of drilled core, such as hardness, shape, crack width and nature of cracks.
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  • Kiyoshi MIURA
    1976 Volume 17 Issue 4 Pages 168-175
    Published: December 30, 1976
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    The characteristic altered biotites are observed in the weathered granite at eastern part of Tottori prefecture, Japan,
    From the mineral assemblage, they are classified into following types:
    (1) Kaolinite+interstratified Chlorite-Vermiculite
    (2) Kaolinite+Vermiculite + interstratified Chlorite-Vermiculite
    (3) Kaolinite+Chlorite+Vermiculite+ interstratified Chlorite-Vermiculite.
    The hydroxy-aluminium interlayer may form in the all of discrete vermiculite and interstratified vermiculite.
    They are different from the mineral assemblages of weathered biotite.
    Judging from the mode of occurrence, they were formed from the altered chloritic biotite under the weathering condition.
    They gives a evidence of hydrothermal alteration before weathering of the parent rock.
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  • With Special Reference to the Results of Statistical Analysis
    Shin IWANAGA
    1976 Volume 17 Issue 4 Pages 176-186
    Published: December 30, 1976
    Released on J-STAGE: March 25, 2010
    JOURNAL FREE ACCESS
    (1) In the Haizume formation, landslides took place less frequently and in smaller scale as compared with those in the other Neogene formation in Niigata prefecture. The traces of large ancient landslide are found in the vicinity of anticlinal axis, though in smaller number in comparison with the landslides in the Uonuma group.
    (2) With the deviation angle, which is the intersection angle of landslide direction and dip direction, at higher value, landslides are less distributed in the manner of geometric progression. The relationship between deviation angle and the number of landslide distribution is represented by the following equation:
    x=473-231logy
    whese y is the distribution number of landslide masses, and x is the classification value at every 10° of deviation angle.
    (3) In the Haizume formation the aforegoing relationship is not observed so remarkably as in the Uonuma group, showing an intermediate tendency of those in the Nishiyama formation, where many landslide masses are found along the strike direction, and in the Uonuma group, where dip slides are predominant.
    (4) The relationship between the average area of landslide masses and the deviation angle is rather dispersive, without indicating any definite tendency. Generally, however, strike direction slide takes place in smaller area, and landslide takes place in larger area in the vicinity of anticlinal axis, particularly on the folding axis.
    (5) At the place with deviation angle at higher value, the inclination of land formation is steeper, showing a similar tendency as observed in the Uonuma landslide distribution.
    (6) The area of landslide mass and the inclination of land formation is in such reciprocal relation as with one factor at greater (or smaller) value, the other factor is smaller (or greater) in its value in the manner of geometric progression, such relationship being represented approximately by the following equation
    y=20.4-7.3logx
    where y is the average inclination of land formation of landslide mass, and x is the area (ha) of landslide mass.
    (7) Landslide tends to take place with the inclination of land formation at 10-15°, and the landslides in small areas of 0.2-1.0ha are most predominant.
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  • Ryuma YOSHIOKA
    1976 Volume 17 Issue 4 Pages 187-196
    Published: December 30, 1976
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    The present paper is mainly concerned with the dissolved major constituents of natural waters in landslide areas. The following items are discussed: (1) Relation between chemical composition and discharge of ground waters, (2) Partial pressure of dissolved carbon dioxide gas of ground waters, and (3) Mineral-water interactions. And the author has emphasized a geochemical method for clarifying the role of weathering processes and landslide phenomenon.
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