The Solution Mining Research Institute (SMRI) has recently embarked on inquiries into the effect cyclic loading (both mechanical and thermal) might have on salt. Some of this interest stems from the concept of using salt caverns as a storage medium for renewable energy projects (e.g., Compressed Air Energy Storage [CAES] with wind power) where daily pressure cycles in the cavern are conceivable as opposed to the seasonal cycles expected for typical natural gas storage projects. RESPEC and the Institut für Aufbereitung und Deponietechnik (Chair for Waste Disposal Technologies and Geomechanics) at Clausthal University of Technology (TUC) jointly executed a rock mechanics laboratory study using both facilities for performing triaxial cyclic loading creep tests on rock salt recovered from the Avery Island Mine in Louisiana, USA.

The cyclic triaxial creep tests were performed under various load paths including compression, extension, and compression/extension. In addition, the tests were performed under both dilative and non-dilative stress regimes. The cyclic compression creep data was compared to static creep tests performed under similar conditions and the results indicated that the cycling of the applied stress did not have a dramatic effect on the specimen’s creep rate as long as the applied stress was not in the dilational regime. Furthermore, the cyclic compression tests were compared to a numerically simulated creep test at the same stress and temperature conditions, and the comparison matched closely for the nondilational loading segment.

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