Rock rheology is common in engineering practice, which has an effect on long-term security and stability of the project. Engineering practice shows that the instability and destruction of rock excavation does not occur immediately after the completion of the excavation, it is has the time effect. In order to understand the rheological mechanical properties of sandstone under the condition of unloading, rock servo-controlling rheology testing machine was used to have a rheological mechanical unloading triaxial test on sandstone, which got typical creep complete test curves of rock. The variation laws of rock deformation with time went was analyzed under different confining pressure, the deformation properties of different rocks in the rock triaxial rheological process were studied, and the development trends and characteristics of rock deformation in stage of accelerated rheology were discussed. Rheological test results show that rheological phenomena occured in sandstone, and its rheological properties were significant with large rheological deformation, especially in high-stress conditions, When the external load exceeded the long-term strength of rock samples, specimen deformation went through three typical rheological stages with time increasing, and ultimately speed up to breakdown. Based on the results of triaxial compression rheological experiments, the parameters of Burgers rheological model were identified with the optimized algorithms, the non-stationary law between rheological parameters and confining pressure were studied. From the regression analysis results, it can be seen that the precision of the results of the exponential function is slightly lower than the return fitting power function fitting precision.
