Suction caisson installation in sand with isotropic permeability varying with depth

Ouahid Harireche*, Moura Mehravar, Amir M. Alani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Suction-induced seepage is pivotal to the installation of caisson foundations in sand. Indeed, the upward pore water flow on the inner side of the caisson wall causes a release of a fraction of soil resistance due to the reduction of the lateral effective stress. A safe caisson installation requires a reliable prediction of soil conditions, especially soil resistance and critical suction for piping. These soil conditions must be predicted for the whole installation process.In this paper, we examine the effect on such prediction of the assumed permeability profile, which is described as a function of depth below the mudline. This study is motivated by the fact that marine sediments generally exhibit a permeability that decreases with depth because of consolidation under gravity. Hence, the question is whether conventional theories based on a constant permeability lead to a conservative prediction of soil conditions or not. Our conclusion is affirmative only regarding piping condition. As for soil resistance, a prediction based on the assumption of a constant permeability is non-conservative. This is due to an overestimated reduction in effective stresses under suction-induced seepage.

Original languageEnglish
Pages (from-to)256-263
Number of pages8
JournalApplied Ocean Research
Volume43
DOIs
Publication statusPublished - 6 Nov 2013

Bibliographical note

© 2013, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/

Keywords

  • caisson foundation
  • installation in sand
  • normalised geometry
  • permeability varying with depth
  • piping condition

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