Journal of the Japan Society of Engineering Geology
Online ISSN : 1884-0973
Print ISSN : 0286-7737
ISSN-L : 0286-7737
Volume 45, Issue 1
Displaying 1-4 of 4 articles from this issue
  • Application to a Quarry Slope of Unevenness
    Shogo HOSOYA, Masashi NAKANE, Naoki MATSUMOTO, Masuyuki UJIHIRA, Kiyos ...
    2004 Volume 45 Issue 1 Pages 2-12
    Published: April 10, 2004
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Authors have been studying for these several years on 3-dimensional rock fall simulation program to evaluate rock fall characteristics such as falling velocity, rolling angular velocity, falling trajectory, jumping height, horizontal spread and travelling distance correctly. In a pre vi ous paper, mathematical theory and calculated results for a simple slope were described and discussed. In this paper, judgement method of a triangular element on which the gravity center of a falling block is projected, judgement method if a block corner is contacting or not to the slope surface and providing method of unevenness to a slope are described in detail. Following points were made clear from the examination of role of unevenness to rock fall characteristics. 1) Method to g iv e unevenness against a slope by adding random numbers to apices of triangle elements of the slope is available. 2) Falling velocity, rolling angular velocity and jumping height don't change with the change of unevenness of the slope. 3) Falling trajectory, travelling distance and horizontal spread change considerably with the change of unevenness of the slope. 4) It is considered that this 3-D rock fall simulation program could be used practically, providing a slope model drawn by surveyed coordinates.
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  • Method of Scale Correction Considering Slope Angle
    Masuyuki UJIHIRA, Ippei NAKAJIMA, Youhei KAWAMURA, Minoru KAWAKITA
    2004 Volume 45 Issue 1 Pages 13-21
    Published: April 10, 2004
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    It is available to measure the scale of objects applying magnification equation of lens for a photographed image, when the objects are lying in a distant place or too dangerous to access to the places. In practical cases, accurate scale of object can not be measured correctly when only the magnification equation of lens is applied simply to an image, because objects both lying in near place and distant place are photographed in the same frame. Here, method of scale correction was studied initially, because the way of scale correction itself considering slope angle was necessary to calculate the correct lengths of photographed objects. Then, validity of the scale correction method considering slope angle was examined, applying this method to an object model of hexagonal shape on a slope, distributed rocks on a flat board and excavated rocks by blasting. From these examinations, it was confirmed that corrected rate on the scale of hexagonal model was 0.85-1.04 and the rate on the distribution characteristic value of excavated rocks by blasting was 0.94. This correction method is considered to be available for the scale measurement using a photographed image.
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  • Toshikata ITO, Takeshi KOMATSUBARA, Osamu SATO
    2004 Volume 45 Issue 1 Pages 22-30
    Published: April 10, 2004
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    The deep ground water in the northern Fossa Magna region where thick formations in the Neogene and later periods are distributed is represented by Na·Cl type groundwater originating from fossil seawater.
    The high-density Na-Cl type groundwater has risen to a shallow depth under the ground surface. Monitoring the electric conductivity of the groundwater could help identify the geological structures such as active faults.
    The Cl concentration in strong salt springs that are mixed with little meteoric water decreases, and δ18O increases in formations of later geological periods. Measuring the Cl concentration and δ18O could therefore enable the estimation of the period of the fossil seawater from which the strong salt spring originates, and may be effective for determining the rock from which hot spring seepage occurs.
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  • Takeshi KUWANO, Yasuhito SASAKI, Yasuhiko WAKIZAKA
    2004 Volume 45 Issue 1 Pages 31-41
    Published: April 10, 2004
    Released on J-STAGE: February 23, 2010
    JOURNAL FREE ACCESS
    Rock mass failures are one of the serious natural disasters, and the failures can affect the considerable damage to the region as suffered at the Toyohama Tunnel Collapse, northern Japan, in 1996. Therefore, it is very important to identify the extent of the hazard area precisely and effectively from the viewpoint of making hazard maps. In this paper, we analyzed the factors and their contributions that affect the extent of the hazard area on the rock mass failures, dealing with angles of elevation and spread using the quantification theory type I that is one of the multivariate analysis. And we discussed potential availability of probabilistic prediction on the hazard map.
    As a result, we recognized that the angle of elevation depends largely on the volume of the rock mass and the type of the failure, and slightly on the slope condition of the lower part of the failure. The angle of spread depends largely on the elevation and the width of the failure source respectively. The coefficients of determination on the prediction of the hazard area are approximately 0.55 using the multiple linear regression analysis of the angles of elevation and spread, it seems possible to predict the hazard area by the analysis. Besides, we could assess the probabilistic prediction of the hazard area by means of the probability distribution of the residual value between actual value and predicted value on the hazard area. These quantitative predictions of the hazard area should become useful data with the object of making GIS hazard maps on the rock mass failures.
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