An elasto-plastic model for unsaturated soil incorporating the effects of suction and degree of saturation on mechanical behaviour

Abstract

The authors should be commended for presenting such an innovative, elaborate elasto-plastic framework for predicting constitutive unsaturated soil response under isotropic stress states. One of the key aspects of the work is the authors' deep knowledge of the physical interactions that lie behind the mechanical behaviour of unsaturated soils. The proposed constitutive model and their associated conceptual framework provide an important improved understanding of soil behaviour. The present review is intended to offer some comments that further highlight the relevance of the work and its potential for further refinement and tuning.The objective of this review is twofold:

Effective stress concept in unsaturated soils: Clarification and validation of a unified framework

“…Gallipoli et al [47] plotted a similar interpretation with the Bishop's generalized effective stress, interpreting slightly curved shapes for compressions rather than lines, Figure 11. However, Figure 10 shows that a linear model could fit well the compression lines in the plastic part and that inflexions of the experimental curves, if some, are likely to appear only at high mean effective stresses or might not be significant.…”

“…Such a constitutive context, however, implies the use of multiple coupled yield loci and a high level of complexity in the formulation. A quite opposite contribution concerning the second stress variable is the work from Gallipoli et al [47]. The authors consider that many features of the elasto-plastic behaviour are linked to bonding phenomenon between particles, which are linked to menisci.…”

A Coupled MPM-FDM Analysis Method for Multi-Phase Elasto-Plastic Soils

“…In this study, skeleton stress (Jommi, 2000;Gallipoli et al, 2003) is used for the stress variable in the constitutive relation for the soil skeleton (Oka et al, 2006(Oka et al, , 2008b(Oka et al, , 2010Kimoto et al, 2007). The total stress tensor is assumed to be composed of three partial stresses for each phase.…”

“…In the MPM, constitutive equations can be easily applied because history-dependent variables, such as plastic strain and strain-hardening parameters, are carried by each material point. As the stress variable of the constitutive model, skeleton stress (Jommi, 2000;Gallipoli et al, 2003) is used to describe the mechanical behavior of unsaturated soils (Oka et al, 2006(Oka et al, , 2008b(Oka et al, , 2010Kimoto et al, 2007). For the full description of the behavior of unsaturated soil, it is necessary to incorporate the suction in the constitutive model.…”

Bridging Effective Stress and Soil Water Retention Equations in Deforming Unsaturated Porous Media: A Thermodynamic Approach

“…Usually, this is done by defining an effective stress (Gallipoli et al 2003a;Khalili et al 2004;Gens et al 2006;Sun et al 2007Sun et al , 2008. Among different stress state variables that have been proposed for modelling unsaturated soils, the effective stress has proved to work satisfactorily for modelling unsaturated soils (Khalili and Khabbaz 1998;Khalili et al 2004;Lu 2008).…”