Abstract: Based on the mechanical test and the Norton Power law of salt rock, a new constitutive law of salt rock is presented. The new constitutive law can embody the steady creep and the accelerative creep of salt rock by importing the damage variable. The damage equivalent stress is the function of confining pressure and deviatoric stress in the new constitutive law. The parameters of the constitutive law were obtained by simulating the experimental data of salt rock in some salt mine. The theoretic results accord with the experimental results. By the three-dimension numerical method, the new constitutive law is programmed. The natural gas storage in the salt mine is analyzed by the new constitutive law. The evolvement law of damage bound and the displacement law around the natural gas storage is studied under the minimal natural gas storage pressure. The continuous operating time of the natural gas storage is also analyzed under the pressure. The study indicates that: (1) The presented constitutive law has good numerical stability during the accelerative creep. (2) The extension of the damage bound around the storage is very fast after the salt rock around the storage enter the accelerative creep phase under the minimal operating pressure. The most dangerous position of the storage is the top. (3) The steady volume convergence becomes steady and the damage creep volume convergence develops very fast after the salt rock around the storage enter the accelerative creep phase. (4) The continuous operating time of storage can’t exceed three months under the minimal pressure.

Key words: salt rock, gas storage, creep, damage