Analysis Of Viscoelastic-plastic Deformation And Stability Of A Cavern In Bedded Rock Salt Under Injection And Recovery Pressure

Rock Salt is a kind of low permeability and damage self-healing material, which was recognized as an ideal medium for the storage of natural gas. However, in our country, there is plentiful mudstone interlayer in the salt mines, the deformation and the intensive properties different from common rock. Fully considering these problems, in this paper based on previous rock salt and layered rock salt research results, according to the existing problems of deformation and stability in the operation process of rock salt, some research were carried out and got some useful results.1. The creep characteristics of the rock salt and the layered rock salt were summarized through uniaxial and triaxial test.2. For the gas storage suffered cyclic load during operation, using the software FLAC3D, numerical simulations on the layered rock salt cavern, which operation internal pressure is cyclic load.3. Establishment of a rock salt cavern gas storage with stable operation pressure for comparative analysis.4. Using WIPP constitutive model to analysis the viscoelastic deformation on the cavern, and then using the PWIPP constitutive model to analysis the viscoplastic deformation and stability on the cavern,5. The results show that the deformation of the surrounding rock in cavern by cyclic load presented a wave type, in viscoelastic and viscoplastic conditions, the cavern convergence deformation is basically the same, which both presented a concave and convex shape. Considering the elastic deformation of interbedded mudstone, the plastic zone of interlayer expanded through entire rock mass, which induced natural gas leak and result in instability of the cavern. Considering the plastic deformation of interbedded mudstone, the plastic zone of interlayer expanded about53m into the surrounding rock mass, but not through entire rock mass, and the cavern is stable.