By lots of creep test researches

artificial frozen clay shows an obvious creep behavior under high deviatoric stress. When artificial frozen clay in low stress level

a viscoelastic creep deformation presents. While in high stress level

viscoplastic creep deformation presents. On the basis of Nishihara model

parabolic viscoelasto-plastic creep constitutive model is constructed by adding a viscoelastic element and parabolic yield function instead of plastic yield. The modified Nishihara model can describe the shear creep characteristics of artificial frozen soil well. Based on niche technology

genetic algorithm and viscoelasto-plastic theory

the model of viscoelasto-plastic displacement back analysis for artificial frozen soil has been set up by finite element program generator (FEPG). With the measured data

displacement back analysis is conducted during the excavation of deep freezing shaft. And the obtained parameters of mechanical model for frozen soil agree with the test results. The deviation between numerical calculation results and measured data is less than 6%; so the inversion results verify the feasibility of the model. The constitutive model parameters

which obtained by displacement back analysis for artificial frozen soil

can reflect the average of frozen wall construction process and effective freezing range. So it has wide representation and important engineering significance for frozen wall stress field

displacement field and stability prediction.