Study On Elastic-plastic Damage Constitutive Model Of Frozen Soil Based On Energy Dissipation Theory

Early constitutive theory of geomaterials, seek answers in differential equation only according to the conditions of the mechanical control and not including energy principle. For the general deformation process, complete differential equations must include an energy principle, in respect that external force does work inevitable part of energy to the form of heat dissipation. Starting from the thermodynamic assumption, make energy dissipation function, study on yield surface and flow rule of dissipative stress space and true stress space, and develop plasticity theory. This method not only has the better of universality, but also a clear theoretical basis. In this paper, frozen soil constitutive model is studied in above method.Existing substantial research results show that: frozen soil under loads has a large number of micro-cracks initiation and growth and reorientation of soil particles, so that the effective area of decreases and carrying capacity lowers. Therefore the deformation process of frozen soil is studied by damage theory is appropriate.Based on energy dissipation theory, 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 elasto-plastic and damage evolution, frozen soil incremental elastoplastic damage constitutive model is made. And finite element scheme is given.Plastic-related model parameters can be obtained in conventional uniaxial, triaxial test. When frozen soil is damaged, it is indirectly reflected in the elastic modulus changes; At the basis of deviatoric stress-strain curves, and through changes of the secant elastic modulus of frozen soil, changes of damage are performed, so the damage -related model parameters are established.The result that finite element simulation model curves and experimental curves match well illuminates: the founded model conforms to reality and in favor of further study and application.