Journal of the Japan Society of Engineering Geology
Online ISSN : 1884-0973
Print ISSN : 0286-7737
ISSN-L : 0286-7737
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Volume 53, Issue 2
Displaying 1-4 of 4 articles from this issue
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Original Article
  • Mechanical Anisotropy and Sedimentary Structure in Kimachi Sandstone, Part 1
    -Grain Fabric-
    Yukiyasu FUJII, Hyuck PARK, Takato TAKEMURA, Manabu TAKAHASHI, Naoki T ...
    Article type: Original Article
    2012 Volume 53 Issue 2 Pages 64-69
    Published: June 10, 2012
    Released on J-STAGE: February 28, 2014
    DOIhttps://doi.org/10.5110/jjseg.53.64
    JOURNAL FREE ACCESS
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     The anisotropy of magnetic susceptibility is measured in Kimachi sandstone, which is massive sandstone from Miocene Omori Group. Grain fabrics are also measured on three planes, they cross orthogonally, one is horizontal and others are parallel / vertical to the paleo-current direction which is rarely observed in a quarry. Measuring the grain fabrics, grain shapes on each plane are traced as ellipses, and long axes of them are measured. The most preferred orientation of long axes of the oval grains is ENE-WSW as same as the direction vertical to the paleo-current. The second preferred orientation of long axes of the oval grains is NNW-SSE as same as the direction of the paleo-current. The vertical direction, in which there is no preferred orientation of long axes, is as same as the direction of minimum magnetic susceptibility. It is cleared that Kimachi sandstone has anisotropy of grain fabrics, even if it seems massive one without bedding planes.
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  • Free-Settling Phenomenon of Particles at Large Reynolds Numbers
    -Free-Settling Experiment
    Kenji MATSUMOTO, Shuichi NAGAOKA, Hiroyuki OHNO, Yusaku ISOBE, Hironor ...
    Article type: Original Article
    2012 Volume 53 Issue 2 Pages 70-79
    Published: June 10, 2012
    Released on J-STAGE: February 28, 2014
    DOIhttps://doi.org/10.5110/jjseg.53.70
    JOURNAL FREE ACCESS
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     On offshore disposal site, alluvial clay layer is frequently used as the bottom hydraulic barrier layer. The layer thickness of hydraulic barrier should be thicker than a regulated value, and must not be decreased by the settling and impact of sea-reclaimed wastes. Knowing the settling phenomena of reclaimed wastes is very important to grasp the influences of offshore constructions on the ambient environment. Although the numerical analysis methods for such phenomena have been developed in recent years, it is difficult to develop the appropriate analysis. Here, the results of the free-settling experiments at laboratory and in situ to examine the large Reynolds numbers are reported.
     As a result, on free-settling of single particle, the actual settling velocity is 0.5-1.0 times as fast as the terminal settling velocity which is calculated by Newton's experimental equation. On free-settling of multiparticle, the maximum settling velocity is faster than single particle's, though minimum velocity is slower than single particle's. In this case, its actual settling velocity is 0.5-2.0 times as fast as the velocity calculated by the Newton's equation.
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Report
  • Extending Wire-Line Core Drilling Method for Soft Rocks
    -Technological Development of Drilling tools and Applicable Drilling in Coastal Zones at Horonobe, Hokkaido-
    Masaru KOSHIGAI, Masamitsu YOSHIOKA, Akihiro KITAMURA, Atsunao MARUI
    Article type: Report
    2012 Volume 53 Issue 2 Pages 80-88
    Published: August 10, 2012
    Released on J-STAGE: February 28, 2014
    DOIhttps://doi.org/10.5110/jjseg.53.80
    JOURNAL FREE ACCESS
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     The drilling survey of soft rocks, which are thickly distributed in the subsurface of coastal area of Japanese islands, has a lot of task to be solved. Among the various drilling methods, the wire-line core drilling method has the advantage of being the most efficient, and it is generally adopted for conducting drilling surveys at depths of over 200 m. However, wire-line drilling method leads to an excessive increase in water pressure and to a low core collection rate of soft rocks because in wire-line drilling, the space between the tools and the borehole walls is very narrow. Therefore, we developed wire-line drilling tools that are larger than the standard-size tools. In addition, the new wire-line type single core tube was developed due to remove cuttings or debris quickly and keeps a high core collection rate. As the result, we succeeded in achieving a high core collection rate and obtaining good quality core while maintaining a high operational efficiency.
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