Abstract: In order to study the creep mechanical characteristics of backfill，a step loading uniaxial compression creep test was carried out with RLW-3000 shear creep testing machine controlled by computer.The result showed that the higher the load，the faster the deformation and the deformation rate of backfill.The pressure and extension of internal defects and weak surface of backfill，show the creep deformation of backfill on the macro level.Assuming that there exists a relationship between the failure probability of backfill micro-element and axial strain，and the failure obeys the Weibull distribution.Combined with the uniaxial compression test，the damage variable of the backfill damage evolution process can be described.And the damage variable is introduced into the Burgers model；the statistical damage constitutive model is established.MATLAB software was used to fit the creep test data of backfill，and the model parameters were determined.The results showed that，the model curves tallies with the experimental curves.The higher the stress level is，the higher the accuracy of the fitting results is，and this model can be used to describe the creep behavior of backfill.

Key words: Backfill, Weibull distribution, amage variable, Creep model