Analysis Of Creep Damage Coupling And Stability Of The Salt Rock Cavern

Salt rock is a kind of soft rock, with compact structure, low porosity, large plastic deformation capacity, very low permeability, good creep behavior and the damage character such as self-healing, is internationally recognized as the oil and gas caverns and radioactive waste disposal. Salt rock in China, however, has weak intercalations and different characteristics of the single thin layers. So we can’t draw lessons from experience of other countries, and the difficulty is to certain extent increased in the research. In this paper, combining with the results of previous scholars, damage is taken into consideration; the creep damage coupling and the stability of the salt rock cavern are studied.1. From the triaxial creep damage tests, it is seen that the creep damage characteristics of salt rock includes the formation of elastic and transient creep deformation, steady-state creep damage characteristics and the accelerated creep damage characteristics.2. Mudstone is a kind of hard rock in comparasion to salt rock. In the beginning period of loading, the damage value is lower than salt rock, and it is almost the same as salt rock in the late period of loading. It is good to rationally increase the internal pressure for restricting the development of damage.3. Using the models of PWIPP and userc_d the numerical simulations are carried out. The behaviour of the salt rock cavern under the both situations is almost the same in deformation, stress distribution and change rule; the difference is just in numerical value; under the situation of userc_d model the deformation is slightly recoverable after the completion of the damage, but this recovery is not reliable.4. The stability of the storage cavern can be guaranteed under the two situations using the two models. But the damage area under the situation of the userc_d model is slightly larger than the plastic zone under the situation of the PWIPP model.