Numerical simulation technology is crucial in underground engineering for predicting the long-term deformation of rock rheology. A numerical simulation analysis method for rock aging is proposed

utilizing a generalized fractional derivative component based on fractional calculus to capture generalized stress relaxation characteristics

where the parameters are employed to describe the dynamic stress change process of rock. The generalized fractional derivative component is connected in series with the improved Burgers model for strain correction

allowing the model to describe the different rheological directions of rock when stress changes. The established model is further derived into a three-dimensional central difference format for a computational time step

then compiled using C++ and FISH languages

and embedded into the numerical simulation software FLAC3D. Simulation results are compared with the generalized stress relaxation test conducted on tuff. The results show that the secondary development of the generalized stress relaxation rheological model can well simulate the strain change law in different rheological directions of rock

reflecting the generalized stress relaxation characteristics of the rock. This helps to determine a reference range for the rheological deformation of the rock

aiding in more accurate prediction of the long-term deformation of engineering rock masses caused by disturbances such as excavation that leads to changes in the stress field environment.