Localized failure in unsaturated soils under non-isothermal conditions

Fluctuations of temperature and degree of saturation have considerable influence on the mechanical, hydraulic and retention properties of unsaturated soils. Localized failure is a ubiquitous feature of geomaterials. Major research on localized failure of geomaterials has been focused on geomaterials under the isothermal condition. In this article, we study the localized failure of unsaturated soils under non-isothermal conditions. In particular, we derive the isothermal and adiabatic bifurcation conditions from a homogeneous deformation at the constitutive level under a locally drained condition. A recently proposed meso-scale constitutive model for thermal unsaturated soils is used to derive the isothermal and adiabatic acoustic tensors. We present the spectral form of the consistent tangential elasto-plastic operator from a local material integration algorithm. The numerical simulations at the material level are conducted to study the impact of temperature on localized failure of unsaturated soils under the plane strain condition. The numerical results show that the timing and the critical angle of bifurcation are dependent on temperature.