生体触媒を活用した炭酸カルシウム結晶析出による地盤固化効果の検討  [in Japanese] SOLIDIFICATION OF SAND SOILS INDUCED BY CALCIUM CARBONATE PRECIPITATION UTILIZING BIOCATALYST  [in Japanese]

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Abstract

本研究では,生体触媒であるウレアーゼの尿素加水分解機能を利用した炭酸カルシウム結晶析出による地盤固化効果の検討を行った.まず,直径50mm,高さ100mmの円柱砂供試体に所定の濃度に調整したグラウト材を注入し,改良体の力学特性を評価した.その結果,炭酸カルシウム析出量の増加と共に強度が増加する正の相関が得られた.つぎに,より大型な砂地盤内にグラウト材を注入することにより,砂地盤の固化程度を評価するために,ドラム缶内に直径560mm,高さ600mmの砂層地盤を作製し,濃度調整したグラウト材の注入試験を実施した.その結果,概ね想定した領域を改良することができ,本手法の有用性を示すことができたが,改良体の強度制御が今後の課題であることが確認された.

 In this work, the soil-ground solidification by calcium carbonate precipitation has been examined utilizing a urea hydrolysis enhanced by urease. Firstly, a suite of the small cylinder tests (50 mm in diameter and 100 mm in height) was conducted to evaluate the evolution of mechanical properties in the im-proved sand soils mediated by the grout injection. The results show that the strength of the improved samples increases with increase of the amount of calcium carbonate precipitated. Specifically, a uniaxial compressive strength of 3.4 MPa was obtained in the sample with approximately 4 wt.% precipitation against the sand weight. Secondly, drum-can tests (560 mm in diameter and 600 mm in height) were per-formed to examine the validity of this technique. It is concluded that the current technique may be ap-plicable to real fields although the strength of the improved sand should be well-controlled prior to the in-situ application.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. C (Geosphere Engineering)

    Journal of Japan Society of Civil Engineers, Ser. C (Geosphere Engineering) 70(2), 290-300, 2014

    Japan Society of Civil Engineers

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