ABSTRACT
Onset of strain localization signifies the inception of narrow zones, orders of magnitude smaller than the underlying macro-scale problem, within which large strains develop with continuous loading. These zones were initially referred to as shear bands, and more recently as deformation bands. Although strain localization is pertinent to elastic-plastic solids such as soils the vast amount of research completed so far had been devoted primarily to dry soils. While some results are available for fully saturated soils the amount of research covering unsaturated soils is scarce at best. To this end the condition for onset of strain localization in unsaturated elastic-plastic materials was derived within the framework of mixture theory (Eringen & Ingram 1965, Bowen 1976) in conjunction with the effective stress definition proposed by Khalili & Khabbaz, (1998), and Khalili et al. (2004). Based on this, a diagnostic analysis for detection of onset of strain localization in unsaturated soils was implemented into a constitutive driver for bounding surface plasticity model. A strain localization behavior was further illustrated on the example of Bourke silt from New South Wales, Australia.
