不飽和砂質土の繰返しせん断変形解析における間隙空気圧のモデル化の影響  [in Japanese] PORE AIR PRESSURE EFFECT ON CYCLIC SHEAR BEHAVIOR OF UNSATURATED SANDY SOIL  [in Japanese]

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Abstract

本研究では,三相系多孔質体理論と簡易な弾塑性構成式による液状化解析法を用いて不飽和砂質土の非排気・非排水繰返し三軸試験のシミュレーションを実施しその適用性を検討した.また,不飽和土の繰返しせん断変形解析を実施する際に取扱いが問題となる間隙空気圧について前述の三相解析と間隙空気圧と間隙水圧を等しく(<i>p<sup>a</sup></i> = <i>p<sup>w</sup></i>)した二相解析を用いて検討を行った.その結果,提案する手法により初期のサクションが10kPa以下の場合には,飽和度が50%以上であれば繰返しせん断時の有効応力や間隙水圧,間隙空気圧,間隙比の挙動が再現可能であることを示し,さらに二相解析は,間隙空気の圧縮性を簡易に取り扱う為に三相解析に比べ繰返しせん断に伴う体積収縮について実験値と解析値で生じる差が大きく収縮量を過大に見積もることを示した.

 Numerical simulations of unsaturated soil cyclic shear tests were performed using the three-phase porous media theory and a simplified elasto-plastic constitutive model for sand. As a result, the simulations provided a satisfactory reproduction of the cyclic test results in the cases where the initial suction was low volume regardless of the degree of saturation. In this study, Furthermore influence of the pore air pressure in the analysis was examined by two methods the previously described three-phase analysis and two-phase analysis with the same pore air pressure and pore water pressure. It was the result the two-phase analysis results would overestimate the volumetric compression compared to the three-phase analysis results due to the influence of the pore air.

Journal

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

    Journal of Japan Society of Civil Engineers, Ser. C (Geosphere Engineering) 69(3), 386-403, 2013

    Japan Society of Civil Engineers

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