Constitutive Model Of Frozen Soil Research Articles

Creep Constitutive Model for Frozen Soils Based on Hardening and Damage Effects

The creep characteristics of frozen soil has significant influences on infrastructure stability in cold regions. It is important for frozen ground engineering to describe the creep properties of frozen soil with accurate models. In this research, a new structure creep model is developed by considering the hardening factor and damage factor which play different roles during various creep stages. According to the experimental results under different stress levels, the proposed model was verified. The calculation results exhibit the proposed model has abilities to predict the creep characteristics of frozen soils, especially the nonlinear stress-strain behavior at acceleration creep stage.

A Dynamic Micromechanical Constitutive Model for Frozen Soil under Impact Loading

By taking the frozen soil as a particle-reinforced composite material which consists of clay soil (i.e., the matrix) and ice particles, a micromechanical constitutive model is established to describe the dynamic compressive deformation of frozen soil. The proposed model is constructed by referring to the debonding damage theory of composite materials, and addresses the effects of strain rate and temperature on the dynamic compressive deformation of frozen soil. The proposed model is verified through comparison of the predictions with the corresponding dynamic experimental data of frozen soil obtained from the split Hopkinson pressure bar (SHPB) tests at different high strain rates and temperatures. It is shown that the predictions agree well with the experimental results.

A Fractional Creep Constitutive Model for Frozen Soil in Consideration of the Strengthening and Weakening Effects

The triaxial creep tests of frozen silty clay mixed with sands were performed under different pressures, and the test results demonstrated that, under the low confining pressure, when the shear stress is lower than the long-term strength, the test specimen exhibits an attenuation creep because the strengthening effect is greater than the weakening effect. When the shear stress is higher than the long-term strength, the test specimen exhibits a nonattenuation creep due to the level of the strengthening and weakening effects change in different stages. As the confining pressure increases, the test specimens only exhibit an attenuation creep because of the enhancing strengthening effect. Both the hardening parameter and the damage variable were introduced to describe the strengthening and weakening effects, respectively, and a new creep constitutive model for frozen soil considering these effects was put forward based on the theory of elastoviscoplastic and the fractional derivative. Finally, the model parameters were analyzed and their determination method was also provided to reveal the trend of parameters according to the triaxial test results. The calculated results of the constitutive model show that the proposed model can describe the whole creep process of frozen soil well.

Study on Elastic-Plastic Damage Constitutive Model of Frozen Soil Based on Energy Dissipation Theory

Starting from the thermodynamics, model of frozen soil is studied by energy dissipation theory and the inside and outside the state variables is given under isothermal conditions. Damage of frozen soil is re-flecked by effective stress and damage tensor in Damage Mechanics. Dissipation function is in form of plastic dissipation function (DP yield criterion) and the damage dissipation function. And plastic dissipation function is coupled of the damage variable. Through the elastic-plastic and damage evolution, frozen soil incremental elastic-plastic damage constitutive model is made. And finite element scheme is given.