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)
  • Takumi SHIRAKAWABE, Hailong WANG, Shigeru GOTO, Shuichi YAMAMOTO, Hide ...
    2021 Volume 77 Issue 2 Pages 103-117
    Published: 2021
    Released: April 20, 2021
    JOURNALS RESTRICTED ACCESS

     Bentonite buffer in disposal project for high-level radioactive waste is expected to delay migration of radioactive nuclides, because it has low water permeability and can fill up the technical gaps between overpack and bedrock by swelling during saturation. However, high-level radioactive waste generates decay heat and it is concerned that bentonite buffer may experience functional decline in terms of swelling property and low water permeability because of the thermal history of the buffer. To address this problem, this study measured swelling pressure and water absorption of bentonite that experienced thermal history. The following conclusions are obtained based on this study: i) Effect of thermal history on swelling pressure may not be significant. ii) Diffusivity and water absorption rate of compacted bentonite specimen with dry density less than 1.6 Mg/m3 may increase for cases when temperature equals or higher than 160℃ and thermal history equals or longer than 30 days. iii) It is expected that thermal history effect on water movement in buffer would be minor for properly designed maximum temperature in disposal site and dry density of the buffer.

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  • Shintaro MIYAMOTO, Yoshihisa MIYATA
    2021 Volume 77 Issue 2 Pages 118-128
    Published: 2021
    Released: April 20, 2021
    JOURNALS RESTRICTED ACCESS

     Advanced soil reinforcement should be useful to carry out road restoration following a disaster. A deployable geocell reinforcement inspired by the self-deployable structure in space and mechanical engineering was designed for the road restoration. The deployment conditions and reinforcement shape were simulated. A series of laboratory tests were conducted to investigate the reinforcing effect, and it was confirmed that the soil-geocell interface shear resistance increases as the cell reinforcement confines the soil dilatancy. Based on the Taylor-Bishop energy correction formula, an empirical formula is proposed for the soil-geocell interface shear resistance.

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