Experimental investigations of the creep-damage-rupture behaviour of rock salt

The creep-damage behaviour of rock salt, especially in the tertiary creep phase has been rarely investigated. The creep-damage-rupture characteristics of rock salt are studied in this paper by applying Wang's creep-damage model, the experimental results of the biaxial destructive creep-damage tests using quasi-static loading on rock salt specimens are presented, complete creep-damage curves are obtained, and the evolution laws of deformation and damage of rock salt in the primary (transitional), secondary (steady-state) and tertiary (accelerating) phases are deduced. The long-term behaviour of dilatancy of rock salt is investigated according to the dilatancy boundary theory and an approximate long-term dilatancy boundary range is obtained. Finally, the long-term strength of rock salt is evaluated for the test samples. The used model proves to conform well to the test data, including in the tertiary creep-damage phase; it can be suitable for the assessment of collapse, cracking, rupture and other long-term failures, and hence for theoretical basis of design in the underground engineering of gas and oil storage cavern, nuclear waste disposal and other facilities in salt deposit. (C) 2014 Elsevier Ltd. All rights reserved.