The long-term shear rheology strength of rock mass is an important base to the analysis of long-term operation stability of the rock engineering. Based on field shear rheology test data of dam zone diabase of Dagangshan hydropower station, the long-term shear rheology strength was obtained by stress-strain isochronal curves method, steady-state creep rate method, and nonsteady-state creep method, respectively, and the results were compared and analyzed. The stress-strain isochronal curves method could provide a more scientific and reasonable way for the analysis of long-term shear rheology strength of diabase. Compared with the short-term shear strength, the long-term shear rheology strength by reason of crack damage propagation had some reduction, internal friction angle decreased by 30.7% and cohesion decreased by 22.6%.
