Abstract: This paper presents an elastoplastic constitutive model unifying thermo-hydro-mechanical modeling for unsaturated soils. It is based on existing hydro-mechanical models of unsaturated soils and experimental evidence of temperature effects on soils. The average soil skeleton stress, modified suction and temperature are selected as stress variables, while the soil skeleton strain, saturation and entropy are selected as strain variables. LY and TY yield surfaces and the hardening laws are adopted for simulating temperature effects on volume change. The predictions are performed on the test results in literature including the isotropic compression tests and triaxial shear tests under different net stresses, suctions and temperatures. The comparisons between measured and predicted results indicate that the proposed model can quantitatively predict the volume change behaviour of unsaturated soils under thermo-hydro-mechanical coupling conditions.

Key words: unsaturated soil, thermo-hydro-mechanical coupling, elasto-plastic constitutive model, volume change behaviour