空気~水~土骨格連成有限変形解析による大規模河川堤防の浸透・地震時挙動の評価  [in Japanese] EVALUATION OF MECHANICAL BEHAVIOR OF A LARGE RIVER LEVEE DURING SEEPAGE AND DURING/AFTER EARTHQUAKE BASED ON SOIL-WATER-AIR COUPLED FINITE DEFORMATION ANALYSIS  [in Japanese]

Access this Article

Author(s)

Abstract

本論文では,空気~水~土骨格連成有限変形解析コードを用いて,実在する砂質土・粘性土互層地盤上の大規模河川堤防の浸透・地震時挙動の評価を行った.まず,河川水位の差に注目した浸透と地震の複合時の解析を実施し,河川水位が高いほど堤内地への被害が大きくなることを示した.次に,基礎地盤の砂質土層が礫質土相当の透水性を有する場合を想定して,非定常浸透と地震時の応答を解析した.非定常浸透時には,砂質土層上部に難透水性の粘性土層があるために,河川から砂質土層に大量の水が供給されて,河川水位上昇後8時間経過時点からパイピング破壊に繋がり得るヒービングが発生することを示した.地震時には,礫質土相当の透水性であれば地震中に間隙水の移動が十分に生じて,難透水性の粘性土層で覆われた礫質土層上部に集水するため,礫質土相当の透水性であっても液状化が生じることを示した.

In this study, seepage/seismic behavior of a large river levee on alternately layered ground of sandy and clayey soil was evaluated by a soil-water-air coupled finite deformation analysis code. The main findings are as follows: 1) Focusing on the river level, the analysis during seepage and during/after an earthquake was performed. The higher the river level, the larger the deformation in a direction toward the landside. 2) If the water permeability of the sandy soil layer is as high as “gravel”, 8 hours after the river level rose, ground heaving which will lead to piping occurred near the landside toe. This is because the permeability of covering clayey soil layer is low and much water was supplied from the river to the sandy soil layer. 3) In the case of high permeability in the sandy soil layer as 2), during an earthquake, even when the river level is low, pore water is able to migrate in the sandy soil layer underlying clayey soil layer with low permeability. This results in liquefaction of the top of the sandy soil layer though the permeability is as high as gravel.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. A2 (Applied Mechanics (AM))

    Journal of Japan Society of Civil Engineers, Ser. A2 (Applied Mechanics (AM)) 71(2), I_621-I_632, 2015

    Japan Society of Civil Engineers

Codes

Page Top