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Investigations regarding soils below phreatic surface as unsaturated porous media

  • Hans-Jürgen Köhler
  • Hector Montenegro
Part of the Springer Proceedings in Physics book series (SPPHY, volume 94)

Abstract

Submerged soils may be considered as an unsaturated porous medium containing gas, water and solids. By using a three-phase model, the mechanical behaviour of such soils can be described by an extended consolidation equation in order to calculate transient pore water pressures, induced by external pressure changes. Microscopic gas bubbles embedded in the pore fluid of the soil skeleton may play a key role in soil behaviour due to the increased gas-water mixture compressibility. Pressure changes applied on such unsaturated submerged soils may cause soil structure deformations such as heaving, settling or even fluidisation. Rapid external pressure reductions such as excavations, draw down loading or ground water level lowering are followed by a delayed pore water pressure propagation. Transient pore water pressures may therefore cause embankment sliding, hydraulic failure and unacceptable deformation. Case studies concerning geotechnical applications are presented. Results from numerical simulations based on Biot’s consolidation equation are compared with computations based on Richards equation. The results are discussed towards formulation of protection measures in order to improve stability requirements.

Keywords

Unsaturated Porous Medium Phreatic Surface Pore Water Pressure Propagation Transient Pore Water Pressure Ground Water Level Lowering 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • Hans-Jürgen Köhler
    • 1
  • Hector Montenegro
    • 1
  1. 1.Federal Waterways Engineering and Research Institute (BAW)KarlsruheGermany

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