ADVANCES IN RESEARCHES OF THE MECHANICAL BEHAVIORS OF BEDDED SALT ROCKS

The engineeringmechanical properties of bedded salt rocks are investigated forthe purpose of understanding energy storage in a deeply beddedsalt rocks formation. Compression tests show that the presence ofanhydrite interlayers affects strongly the deformation and failureof the bedded salt rocks. A `stress drop' phenomenon ofstress-strain curves is observed in low confining pressure casesand it denotes that the anhydrite layers fracture prior to thesalt rocks. Creep tests on the salt rocks, the anhydrites and thecomposite rocks imply that creep deformation of surrounding rocksof a storage cavern is controlled by the salt rock layer, andlong-term volume shrinkage is restricted by the anhydrite layers.Direct shear tests, Brazilian disk tests and TEM tests are carriedout to investigate the mechanical properties of the interfacesbetween the anhydrites and the salt rocks. These experiments showthat the interfaces are bonded perfectly and are strong, whichresults in good sealability and stability of the energy storagecaverns in the bedded salt rocks. Also in this paper, the Cosseratconstitutive theory is extended in special cases and is applied tostability analyses of the salt caverns in the bedded salt rockformation. Finally, several important future research directionson the mechanical properties of the bedded salt rocks are pointedout.