Journal of Japan Society of Civil Engineers, Ser. C (Geosphere Engineering)
Online ISSN : 2185-6516
ISSN-L : 2185-6516
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Paper (In Japanese)
  • Hajime KAWASAKI, Hla AUNG, Noriaki SENTO, Mikio KUBO
    2020 Volume 76 Issue 1 Pages 1-11
    Published: 2020
    Released: January 20, 2020
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     Anchored gabion reinforced soil wall is considered to be more structurally stable than steel-frame-faced reinforced soil wall. In previous studies, apparent cohesive strengths of earth-retaining structures with horizontal reinforcement as well as soilbags which have similar reinforcement effects as gabions were evaluated. However, the effect of the different type of wall facing has not been fully estimated. A series of multi-stage loading tests were done on earth-retaining structure with anchored gabion-faced structure and steel-frame-faced structure. As a result of the tests, it was confirmed that the anchored gabion-faced structure recorded higher performance to withstand horizontal load exerted by the earth pressure. Moreover, the amount of contribution given by the anchored gabion-faced structure to the apparent cohesive strength was evaluated by Mohr-Coulomb failure criterion. When FEM analysis was conducted, it was concluded that further investigation on analytical parameters are needed to accurately replicate the test results.

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  • Kunitomo SAHARA, Motoyuki SUZUKI, Yoshinari FUJITA
    2020 Volume 76 Issue 1 Pages 12-25
    Published: 2020
    Released: January 20, 2020
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     It is important to examine the frictional resistance between a reinforcement and backfill soil used for steel strips-reinforced soil walls, because it is one of the main parameters regulating the wall design. The fine content of soil has generally been evaluated to determine availability of backfill soil. However, it has not been possible to evaluate the actual frictional characteristic of reinforced soil walls with different backfill soil materials on each construction site. In this study, we developed a small and simplified pull-out test apparatus that can be used to evaluate the friction characteristic of steel strips-reinforced soil walls for the use of construction site. We also confirmed the reliability of our developed testing as compared with the field pull-out tests. Furthermore, we propose a method for evaluating the friction characteristics of backfill materials on site before construction, in order to ensure required quality.

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  • Yasutaka WATANABE, Shingo YOKOYAMA
    2020 Volume 76 Issue 1 Pages 26-39
    Published: 2020
    Released: January 20, 2020
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     Evaluation method of the montmorillonite content of the bentonite was investigated based on methylene blue (MB) adsorption tests. The accuracy of simple MB adsorption test, so-called the spot method, was investigated by a blind-prediction test using montomorillonite-sand mixtures. As results, the standard error of the spot method was within 2 mmol/100g when same experimental tools were used. Furthermore, the amount of MB adsorbed obtained by the spot method was corresponding to the saturated amount of MB adsorbed obtained by the spectrometry method, which is a precise measurement method. These results suggest that the saturated amount of MB adsorbed can be determined by the spot method. The saturated amount of MB adsorbed on the collected montmorillonite of Ca-type bentonite, the particle diameter under 0.2 μm, was determined as 150.5 – 151.2 mmol/100g. The montmorillonite content of the bentonite was 75.7 – 76.7 %. This was different from the calculated value using 140 mmol/100g as the saturated amount of MB adsorbed on pure montmorillonite, which was commonly used for evaluating the montmorillonite content in many previous studies. These results imply that it is necessary to use the saturated amount of MB adsorbed on the montmorillonite collected from each bentonites in order to accurately evaluate the montmorillonite content for estimation of the permeability and swelling pressure of the bentonite.

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