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Discussing the definition of the second-order work for unsaturated soils

Authors

  • Giuseppe Buscarnera,

    Corresponding author
    1. Politecnico di Milano, Department of Structural Engineering, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy
    • Politecnico di Milano, Department of Structural Engineering, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy
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  • Claudio di Prisco

    1. Politecnico di Milano, Department of Structural Engineering, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy
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Abstract

The volumetric compaction due to wetting processes is a phenomenon observed quite often in unsaturated soils. Under certain circumstances, saturation events can result into a sudden and unexpected collapse of the system. These phenomena are usually referred to as wetting-induced collapses, without providing any detailed theoretical justification for this terminology. In order to predict in a general fashion the occurrence of coupled instabilities induced by saturation processes, a generalization of the theoretical approaches usually employed for saturated geomaterials is here provided. More specifically, this paper addresses the problem of hydro-mechanical instability in unsaturated soils from an energy standpoint. For this purpose, an extension of the definition of the second-order work is here suggested for the case of unsaturated porous media. On the basis of some examples of numerical simulations of laboratory tests, coupled hydro-mechanical instabilities are then interpreted in the light of this second-order energy measure. Finally, the implications of the theoretical results here presented are commented from a constitutive modelling perspective. Two possible alternative approaches to formulate incremental coupled constitutive relations are indeed discussed, showing how the onset of hydro-mechanical instabilities can be predicted using an extended form of Hill's stability criterion. Copyright © 2010 John Wiley & Sons, Ltd.

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