Time-Dependant Behavior of Solution Caverns in Salt

Creep finite-element analyses of several solution caverns in rock salt were performed to study the long-term behavior of such caverns. The effect of cavern shape (height-to-diameter ratio) and the internal pressure on the time-dependent behavior of caverns were the main objectives. The pattern of creep-induced stress changes around the caverns were studied, and the main aspects were demonstrated through the results of the analyses. The cavern volume closures can be expressed by a simple equation as a function of time, and the accuracy of this expression was verified by the results of the analyses. The other aspects of the time-dependent behavior of the caverns studied were: (1) the influence of a drop in internal pressure; (2) the influence of creep deformations on the results and interpretation of pressure tests for cavity tightness; and (3) the influence of gradual cavity growth due to the leaching process as compared to the analysis of cavity assumed at full size initially.