細粒分を含む締固めた砂質土の土粒子流出特性に関する実験的研究  [in Japanese] An experimental study on characteristic of soil particle effluence of compacted sandy soil containing fines  [in Japanese]

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Author(s)

    • 河井 正 KAWAI Tadashi
    • 東北大学大学院工学研究科・土木工学専攻 Department of Civil and Environmental Engineering, Tohoku University
    • 高木 聖人 TAKAGI Masato
    • 東北電力(元東北大学大学院工学研究科・土木工学専攻) Tohoku Electric Power Company (Former graduate student of Tohoku University)
    • 金 鍾官 KIM Jongkwan
    • Korea Institute of Civil Engineering and Building Technology・Geotechnical Engineering Research Korea Institute of Civil Engineering and Building Technology・Geotechnical Engineering Research Institute
    • 風間 基樹 KAZAMA Motoki
    • 東北大学大学院工学研究科・土木工学専攻 Department of Civil and Environmental Engineering, Tohoku University

Abstract

<p>近年,管渠破損部からの土粒子流出に起因した地盤陥没が多発している。管渠の破損は,老朽化や地震時外力によって発生するが,線状構造物の特徴上,対象が広範囲にわたり調査に多額の費用を要するため,地盤の材料特性により調査や対策の対象範囲の限定・優先順位付けが出来ることが望ましい。土粒子流出現象については,模型実験によるメカニズム把握,空洞調査手法などの研究が精力的になされてきたが,未だ地盤物性に着目した基礎的な研究が十分になされているとは言い難い。本研究では,細粒分を含む締め固めた砂質土地盤内に管渠破損部を模擬した流出口を設け,細粒分含有率,細粒分の種類(塑性の有無),地盤の締固め条件などが流出現象に及ぼす影響について検討した。その結果,流出抵抗には,細粒分含有率のみならず,その細粒分の塑性指数も関係することを確認した。さらに,今回検討した範囲では,塑性指数が大きな細粒分を含む土は,最適含水比よりやや湿潤側に締固めることで土粒子の団粒化を抑制し透水係数が相対的に小さくなるため,より流出に抵抗できることを把握した。</p>

<p>Since the ground surface above the damaged conduits might cave in, and it is difficult to estimate where and when it would occur because vast amounts of conduit are buried in the ground, it is useful to know priorities to the improvements based on the resistance characteristics of the soils. Concerned with this issue, the model tests to investigate the mechanisms and the searching technology for the existing caves were conducted and reported, but research from view point of soil characteristics related to the resistance against effluence is insufficient. In this paper, a series of model tests was conducted to cause soil particle effluence from an opening of the damaged pipe using several kinds of materials including either plastic or non-plastic fines in order to know the influence of both amount and plasticity index of fines on the resistance against effluence. It is proved that the combination of fine's content and plasticity index determine the resistance against effluence. Further, for the soil used in this study having a fine of rather large plasticity index, the resistance against effluence was larger when compacted under the condition of having a little more water content than the optimum water content.</p>

Journal

  • Japanese Geotechnical Journal

    Japanese Geotechnical Journal 13(4), 309-318, 2018

    The Japanese Geotechnical Society

Codes

  • NII Article ID (NAID)
    130007541525
  • Text Lang
    JPN
  • Data Source
    J-STAGE 
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