Transactions of The Japanese Society of Irrigation, Drainage and Rural Engineering
Online ISSN : 1884-7242
Print ISSN : 1882-2789
ISSN-L : 1882-2789
Technical Papers
Case Studies on Three-Dimensional Seepage Failure of Soil within a Cofferdam
Shigeru NAGAITsutomu TANAKAShinya KUSUMI
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2016 Volume 84 Issue 2 Pages II_19-II_30

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Abstract

In the excavation of soil within a cofferdam in a high groundwater area, seepage failure of soil is often a problem. In recent years, a deep and/or large excavation will cause a new type of seepage failure, e.g., due to a concentrated three-dimensional flow. In this paper, three case studies on seepage failure of soil due to a 3D flow were assessed, and the following results were obtained: (1) As for stability analyses of the seepage failure of soil, the method for considering plane shapes of excavation should be recommended. (2) Analyses of FEM seepage flow and stability against the seepage failure of soil, using the prismatic failure concept, can produce the best results for the three cases. The reasons why the soils collapsed were also considered. (3) Three flow conditions: two-dimensional (2D), two-dimensionally concentrated (2DC), and three-dimensional (3D) flows, have a marked influence on stability against seepage failure of soil within a cofferdam. The magnitudes of stability against seepage failure are, in decreasing order, 2D, 2DC, and 3D flows. (4) With respect to the seepage failure problem, an axisymmetric seepage flow through soil within a cylindrical wall can be used to model such a three-dimensional flow.

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© 2016 The Japanese Society of Irrigation, Drainage and Rural Engineering
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