Parameter Identification of a Rate Dependent Constitutive Model for Rock Salt

The tendency to shift from fossil and nuclear energy sources to renewable energy carriers in Germany leads to the necessity to develop effective energy storage systems. Nowadays, caverns excavated in rock salt formations are recognized as the appropriate places for underground storage of energy in the form of compressed air, hydrogen and natural gas. Accurate design of these underground cavities requires suitable numerical simulations employing proper constitutive models to describe the material behavior of rock salt under various geological conditions. In this paper, a rate dependent model is selected to describe the mechanical response of the rock salt around the cavern. This model is implemented in the finite element code CODE-BRIGHT, then its application in numerical modeling of salt caverns is illustrated. Finally, inverse analysis of the synthetic data is performed to identify the material parameters of the selected model. The applied inverse analysis algorithm employs metamodeling technique in order to reduce the computation time of the parameter identification procedure.