In order to study the long-term mechanical properties of the diabase in Dagangshan hydropower station dam site,triaxial rheological tests under different stress paths were carried out on RLW-1000 rheology testing machine,and the stress-strain-time curves under different conditions were obtained.The results showed that the diabase was typical hard-brittle rock which had obvious rheological threshold,and sudden brittle fracture was shown at failure of specimen.Shortly prior to failure, each specimen experienced transient creep,steady-state creep and tertiary creep stage in the fracture stress level,but the transient creep and tertiary creep stage maintained short time. When the applied stress level was closed to the fracture stress,the circumferential creep rates were higher than those of axial, which were the main reason of the volume dilatancy phenomenon of specimen.The continuous development of damage in rheological process caused the decrease of whole strength of rock mass,so the rheological failure strength was lower than the instantaneous failure strength by the triaxial compression test.There was some degree of alteration in the diabase of Dagangshan hydropower station dam site,and the altered minerals showed fine scale-like aggregation.The strength of rock was impaired by the existence of alerted strip,the rupture of rock can occur easily in the interface of poorly crystallized mineral grains and the poorly cemented ones.
