In order to research the nonlinear rheology of expansive soil

the samples of cement-improved expansive soil have been selected to conduct the long-term one-dimensional compression tests. The stress-strain curve family for the improved expansive soil under different stress levels has been gained. The nonlinear rheology reflected by the curve can be divided into the linear viscoelastic creep deformation

linear viscoplastic creep deformation and nonlinear viscoplastic creep deformation. Based on the model theory and genetic creep theory

the rheology model for every category has been built accordingly. For the linear viscoelastic creep deformation and linear viscoplastic creep deformation

the model theory has been adopted to build the component model. For the nonlinear viscoplastic creep deformation

the genetic creep theory has been utilized to formulate the integral creep equation. The materials and equation parameters have been gained through the fitting of experimental data. It is found that the creep curve is consistent with the experimental result well.