Abstract
Warm frozen soil is very sensitive to temperature change in the near
phase transition region, and the relationship between temperature and
physical and mechanical properties can be expressed by constitutive
model. Based on the strain equivalent theory of damage mechanics, the
damage model of warm frozen soil structure under the coupling action of
stress and temperature is established. Based on Mohr- Coulomb criterion,
the nominal stress is used to represent the stress damage of frozen soil
element, the initial elastic modulus is used to represent the
temperature damage, and the composite damage factor is introduced to
describe the coupling relationship between them. Two methods are used to
obtain the shape parameters and scale parameters of the coupled damage
model: method 1 is the full fitting method based on the experimental
data; method 2 is the semi theoretical semi fitting method based on the
characteristic points of the stress-strain curve. Through the triaxial
compression test of frozen sand, it is proved that the simulation
results of the stress-temperature coupled damage model are in good
agreement with the experimental curves. Based on the experimental
results, the results of the two methods are compared, and it is proved
that method 2 is better than method 1 under the condition of strain
softening. By comparing the predicted results of stress temperature
coupled damage model and single stress damage model, it is shown that
the former can effectively reduce the influence of parameter estimation
error on the results and improve the stability of the model.