A macro-micro viscoelastic-plastic constitutive model for saturated frozen soil

A macro-micro creep constitutive model of viscoelastic-plastic deformation characteristics for three-phase saturated frozen soils is derived in this paper based on micromechanics, considering the influences of ice content and temperature. First, creep tests of saturated frozen soils are performed, and the mechanism of creep deformation is discussed from a micro perspective. Then, the micro-scale and macro-scale information are connected by establishing a relationship between the macroscopic strain energy rate and strain energy rate of the ice particles, soil matrix, and unfrozen water. The viscoelastic stress tensor for the three phases of materials is derived using the visoelastic correspondence principle and the micromechanics method. Thus, the macro-micro viscoelastic constitutive model for saturated frozen soils is obtained. Based on this analysis, the viscoelastic-plastic constitutive model is further considered for the viscoplastic properties of the soil matrix and ice particles. In addition, the corresponding relationship between viscoplastic and viscoelastic is established based on the "equivalent" method. Therefore, the macro-micro creep constitutive model of viscoelastic-plastic deformation characteristics for three-phase saturated frozen soils is finally derived. The model parameters are determined based on the creep tests of frozen soils and the model is verified using creep test results for saturated frozen soil. It is also determined that the proposed model can illustrate the influence of temperature and ice content on the creep of saturated frozen soils.