Thermo-elasto-plastic constitutive model of saturated clay considering state-dependent

In energy and environmental geotechnical engineering, such as energy underground structures, nuclear waste disposal, and thermal ground treatment technology, geomaterials are subjected to complex temperature environments. It is necessary to deeply understand the volume change and shear characteristics of soils under temperature effect to ensure the reliability and safety of engineering structures. In order to better reflect the thermo-mechanical characteristics of normal and overconsolidated soils, a state-dependent thermo-elasto-plastic constitutive model of saturated clay is established within the framework of critical state theory and boundary surface plasticity theory. Considering the influence of temperature on yield stress and the critical state line, the hardening parameter is expressed by state parameters of the stress point on the yield surface and the image stress point on the bounding surface. The introduction of state-dependent hardening parameters can balance the simplicity of the proposed model with the ability to predict the mechanical properties of overconsolidated soils. The comparison between the model prediction and the experimental data shows that the established model can reasonably reflect the shear characteristics of saturated clay under drained and undrained conditions at different temperatures, including strain-hardening, strain-softening, dilatancy, and contraction. Meanwhile, the thermally induced volume change behavior under non-isothermal conditions can also be well described. © 2024 Chinese Academy of Sciences. All rights reserved.