The Deformation And Stability Analysis Of Salt Rock Cavern Considering Creep Damage And Damage Healing

Salt rock is a kind of special soft rock. Compared with the ordinary rock, it has more special properties: high density, good plastic deformation ability, low permeability, good creep behavior and the damage self-healing character, it is internationally recognized as the ideal storage place of oil, gas and radioactive waste disposal. Sealing performance of the salt rock gas storage is an important technology and safety index. Due to the effect of creep damage, the deformation and stability problems of the layered salt rock gas storage could cause the external leakage of natural gas. Salt mine in our country has many layers and impurities, according to this characteristic, the creep damage test of the layered salt rock needs to be further analyzed. Using the creep damage model-userc_d_h, based on the finite element ANSYS secondary development, the influence of creep damage and damage healing on the stability of layered salt cave was researched.Firstly, the creep damage characteristics of salt rock was researched based on the existing salt rock rheological damage test. The deformation of salt rocks is from local failure to overall instability, its essence is the process of the damage development and accumulation. But the procedure of salt rock damage and healing is corresponding to the creep rate lowering process.Secondly, based on the creep damage model, userc_d model, developed by professor Wang Guijun, another creep damage healing model called userc_d_h was programmed. The program using FORTRAN language and combing the secondary development technology of finite element software ANSYS, was simple, fast and accurate with high reliability and easy for maintenance.Thirdly, with the self-developed userc_d_h model, the numerical verification was performed through comparing the results of the Mackintosh salt gypsum creep test and the calculated value. Simulating the actual test loading process,namely triaxial loading, the calculation results of the numerical model for the cylinder specimen had a good agreement with the test results, which verified the availability of the program.Finally, the developed userc_d_h model was used to analyze the salt rock reservoir geometry model, which was built by the ANSYS software. The userc_d and userc_d_h model was adopted to analyze the deformation, stress distribution and damage, creep distribution area of the salt rock cavern. The result was compared, we found that the salt rock creep curve slope of the userc_d_h model was decreased obviously when unloading. The level of reduction was due to the value of the unloading pressure. The userc_d_h model made a more accurate description of the deformation law of salt rock, which is very helpful for maintaining the stability of the cavern and preventing disasters.The innovation points: The damage healing effect was joined to the deformation and st ability analysis of the salt rock cave, the secondary development function of ANSYS softwa re was used to simulate the damage of the cavern and the damage healing phenomenon of t he salt rock after unloading.