Experimental investigation on the creep-damage-rupture characteristics of salt rock

The characteristics of salt rock in the tertiary creep phase have been rarely investigated. Based on the results of triaxial multi-staged loading destructive creep-damage tests on salt rock samples, the creep-damage-rupture characteristics of salt rock are studied by means of the creep-damage model proposed by the author, complete creep-damage curves are obtained, and the laws of deformation and damage development of salt rock in the transitional, stationary and accelerating phases are deduced. The model proves well consistent with the test data, even in the accelerating creep-damage phase; it accounts for the creep-damage-rupture characteristics of salt rock. Under the condition of multi-staged loading, the primary creep deformation cannot be neglected. The creep and damage of salt rock occur with load increasing and time, as a result, the clear boundary between the stationary and the accelerating stage cannot be found. The deformation induced by damage will play a crucial role in the total deformation when the material is heavily damaged, e.g. damage factor is greater than the damage accelerating limit, and creep/damage reaches, in macroscopic view, accelerating phase.