Abstract: Triaxial creep tests are performed on Yan'an Q₂ loess to obtain the triaxial creep curves and stress-strain isochronous curves under different water contents and confining pressures. Analysis on the curves reveals that stress magnitude, confining pressure and water content has great impact on the creep characteristics of Yan'an Q₂ loess, and when the stress is higher than the sample's yield stress, obvious nonlinear creep characteristic is found. The visco-elasticity-plasticity creep model of the loess is established by analogy in line with the modeling theory and the test results. On the basis of these, the visco-elasticity-plasticity constitutive creep model of the loess considering instantaneous damage is established, and the relevant parameters are fitted by Quasi-Newton method. The applicability of this constitutive model is verified by comparison between theoretical curve and experimental curve. The research results are of theoretical and practical value for the geotechnical engineering in the loess plateau. 

Key words: Yan'an Q₂ loess, triaxial creep test, creep characteristics, creep constitutive model