ANALYTICAL SOLUTION OF LIMIT STORAGE PRESSURES FOR TUNNEL TYPE LINED GAS STORAGE CAVERNS

Tunnel lined cavern gas storage is a new energy storage method, which helps balance supply and demand, promotes the continuous transition from fossil energy to green energy, and facilitates the realization of national goal of "carbon neutralization and carbon peak". In this paper, the ultimate equilibrium method and the elastoplastic analysis method are used to derive the analytical solution of the ultimate storage pressure of tunnel lined rock cavern gas storage. In the ultimate equilibrium method, the self-weight of the overlying surrounding rock, the force of the fracture surface and the ultimate storage pressure are considered, the rigid cone model is selected, and the upper limit pressure expression is derived. In the elastoplastic analysis method, according to the stress distribution law and shear and tensile strength in the surrounding rock, the upper and lower pressure expressions under elastoplastic conditions are derived. Finally, the analytical solution of the ultimate pressure is determined with considering the results obtained by the two methods. The results show that the relationship between the upper limit pressure and the buried depth is quadratic function, and increases with the increase of lateral pressure coefficient; The upper limit pressure and lower limit pressure determined by the elastoplastic analysis method are linear with the burial depth, and the lower limit pressure decreases with the increase of the lateral pressure coefficient, and the lower limit pressure is not considered for the lined gas storage under the condition of class I surrounding rock. When the lateral pressure coefficient is 1.2, the upper limit pressure is the largest, so the tunnel type gas storage should be built as far as possible under the surrounding rock condition with the lateral pressure coefficient of 1.2. Finally, the recommended pressure ranges of lined rock caverns are given according to the upper and lower limit pressure curves under typical working conditions.