Journal of the Japan Society of Engineering Geology
Online ISSN : 1884-0973
Print ISSN : 0286-7737
ISSN-L : 0286-7737
Volume 44, Issue 6
Displaying 1-5 of 5 articles from this issue
  • Satoshi NISHIYAMA, Yuzo OHNISHI, Hiroyasu OHTSU, Takao YANO, Meiji RYU ...
    2004 Volume 44 Issue 6 Pages 331-340
    Published: February 10, 2004
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    In each country of Southeast Asia, there has been lots of slope hazard including a landslide and a slope collapse caused by the geological feature condition and climate condition, and rapid city development will increases the disaster in the future. However, the technology about city protection against disasters in these countries has been undeveloped technically.
    Authors have been developing a monitoring method of slope behaviors by using digital photogrammetry. Photogrammetry is defined as a measuring technique constructing the modeling of a three-dimensional (3D) space using two-dimensional (2D) images. Photogrammetry has the advantage of measuring deformation of an object by some photos with excellent cost performance. This paper proposes that many engineers are able to carry out photogrammeric work without reliance on photogrammeric technicians and shows that photogrammetry has the advantage of measuring deformation of a slope by some photos with easy measurements. When measurements are performed without control points, the normal-equation matrix has a rank deficiency of 7 depending on the three translations, three rotations and the scale in the network of observations. In order to eliminate the rank deficiency of the normal-equation matrix we must find seven additional equations. We present the geometrical analysis for the problem to measure the three-dimensional coordinates of measurement points without control points. This paper also shows a numerical method for calculating sufficiently good initial approximate values. This performance is suitable for a monitoring tool used for a protection against slope hazard in Southeast Asia. This digital photogrammetric system can remove human skills in measurement tasks, so it is possible to use it immediately when necessary.
    The applicability of digital photogrammetry is discussed with its accuracies in Taiwan. Recently there are a lot of constructed roads passing through the soft rock areas in Taiwan. The main formation of soft rock in this country includes sandstones, shale, and mudstone. Due to the poor engineering properties of soft rock, there are many slope hazards along the road. The digital photogrammetry demonstrates that our method has a high potential to prevent the slope hazards in Southern Asia.
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  • Akito NAKASUJI, Jiro SATAKE
    2004 Volume 44 Issue 6 Pages 341-348
    Published: February 10, 2004
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    In the case of the volcanic eruption of Mount Usu in 2000, there were no victims because the evacuation activities were carried out smoothly, as people made great use of the hazard map of Usu Volcano as a source of information. Also, the Mount Fuji Hazard Map Committee started work in 2001, scheduled to publicize the results in the near future. Although volcanic hazard maps have only recently captured the attention to people in Japan, they have been used in various overseas countries for many years. This paper summarizes the definition of volcanic hazard maps and the method of making volcanic hazard maps, classifies and analyzes the collected foreign cases, and introduces representative examples.
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  • Masayuki NAKAHARA, Satoshi NAGATA, Keisuke TAKAGI, Anwar MAKMUR
    2004 Volume 44 Issue 6 Pages 349-359
    Published: February 10, 2004
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    The geological structure in Indonesia is characterized by the mobile belt composed of the arc-trench systems like as that in Japan. Main characteristics of the engineering geology will be heavy weathering of mother rock due to tropical climate, covering of volcanic deposits, and widely distributing limestone. These characteristics are regarded as factors in a features of rock, occurrence of geological disasters, and difference of land-use. We show the issues of engineering geology as well as the geotechnical countermeasure at project sites through our experience for the development of water resources.
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  • Moussa SANE, Hiromitsu YAMAGISHI
    2004 Volume 44 Issue 6 Pages 360-366
    Published: February 10, 2004
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Like many other coastal cities in West Africa, Dakar is prone to several coastal hazards. The most serious among these hazards is coastal erosion. The Geology of Dakar is mainly dominated by Tertiary igneous rocks, and overlying Quaternary sediments. So far, the area covered by the sediments suffers severe erosion as a result of adverse natural processes and human interferences. The effect of nature is through two modes of strong and constant swells and the action of tidal waves during rough-sea seasons. The contribution of human beings is due to a cumulative effect of poor city planning and overpopulation. Since most of the economically active places in Senegal are concentrated in Dakar, people are partially forced to live in this area so that they can earn something for survival. This concentration of people led to a construction boom, and then, to excessive sand extraction from beaches and dunes. As a result, the balance between erosion and deposition has been changed, and led to gradual lowering of the land and to eventual massive scale of coastal erosion.
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  • Wen-Neng WANG, Toshitaka KAMAI, Haruo SHUZUI
    2004 Volume 44 Issue 6 Pages 367-374
    Published: February 10, 2004
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Sprawling urbanization leads to increases in the risk of landslide damage to residential and industrial suburbs. Several incidents of landslide related damage to urban developments occurred along the Cher-Lung-Pu fault of 1999 Chi-chiearthquake on the eastern edge of the Tai-chung basin in Taiwan, severely damaging homes and infrastructure. Six representative cases of landslides are discussed. They have provided important data concerning the effects of earthquakes in sprawling urban districts, and serve as a useful lesson for the future development of industrial countries.
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