The influence of temperature variation on soils’ strength and deformation cannot be neglected in geotechnical engineering

such as shallow geothermal energy extraction

nuclear waste disposal

and the construction of geothermal structures. To comprehensively describe the thermomechanical behavior of soils

a thermo-elasto-plastic model of saturated clay that incorporates the temperature effect is established based on the disturbed state concept. By considering the thermal dependence of the volumetric strains and critical state

a disturbance function is introduced to reflect the influence of overconsolidation ratio (OCR) on the strength

dilatancy and deformation of saturated clay. The disturbance function is incorporated into the dilatancy stress ratio

potential failure stress ratio

and plastic modulus. Finally

the proposed model is validated through the isotropic heating-cooling tests

temperature-controlled drained triaxial compression tests

and temperature-controlled undrained triaxial compression tests. The proposed model can properly reflect the thermal-hardening and thermal-softening behavior of the saturated clay. The strain hardening and volumetric contraction of normally consolidated clays

as well as the strain softening and volumetric expansion of overconsolidated clays under the drained condition are well captured. Meanwhile

the proposed model can describe the strength and stress paths evolution of saturated clay under the undrained condition.